          United States Court of Appeals
                     For the First Circuit

No. 16-1322
                    UNITED STATES OF AMERICA,
                            Appellee,

                               v.

                         JUAN TANCO-BAEZ,
                      Defendant, Appellant.


No. 16-1323
                    UNITED STATES OF AMERICA,
                            Appellee,

                               v.

                      JOSÉ CEPEDA-MARTÍNEZ,
                      Defendant, Appellant.
                       ____________________

No. 16-1563
                    UNITED STATES OF AMERICA,
                            Appellee,

                               v.

                     PETER ROSARIO-SERRANO,
                      Defendant, Appellant.
                       ____________________

          APPEALS FROM THE UNITED STATES DISTRICT COURT
                 FOR THE DISTRICT OF PUERTO RICO

         [Hon. Daniel R. Domínguez, U.S. District Judge]


                             Before

                       Howard, Chief Judge,
               Kayatta and Barron, Circuit Judges.
     Lydia Lizarribar-Masini, for appellant Tanco-Baez.
     Eleonora C. Marranzini, Assistant Federal Public Defender,
with whom Eric A. Vos, Federal Public Defender, and Vivianne M.
Marrero-Torres, Assistant Federal Public Defender, Supervisor,
Appeals Section, were on brief, for appellant Cepeda-Martínez.
     Jennie Mariel Espada, for appellant Rosario-Serrano.
     Thomas F. Klumper, Assistant United States Attorney, Senior
Appellate Counsel, with whom Rosa Emilia Rodríguez-Vélez, United
States Attorney, and Mariana E. Bauzá-Almonte, Assistant United
States Attorney, Chief, Appellate Division, were on brief, for
appellee.



                        November 4, 2019
          BARRON, Circuit Judge.       Juan Tanco-Baez ("Tanco"), José

Cepeda-Martínez ("Cepeda"), and Peter Rosario-Serrano ("Rosario")

were indicted in the United States District Court for the District

of Puerto Rico on three counts of federal firearms charges arising

out of a drive-by shooting.       Cepeda and Rosario each challenge

their conviction on one of those counts and Tanco challenges his

conviction on two of those counts, while Tanco and Cepeda also

challenge their sentences for their convictions on those counts.

We   reject   all   three    co-defendants'    challenges   to   their

convictions, except for Cepeda's challenge to his conviction on

one of the counts, which we agree is not supported by sufficient

evidence and must be reversed.    We affirm Tanco's sentence, but we

vacate and remand Cepeda's sentence not only for the conviction

that we reverse but also for the one that we affirm, as we conclude

that our reversal of his other conviction requires that result.

                                  I.

          The following facts are not in dispute.      On the morning

of March 26, 2014, Tanco, Cepeda, and Rosario participated in a

drive-by shooting on the Román Baldorioty de Castro expressway in

Carolina, Puerto Rico.    A witness reported seeing a high-speed car

chase that involved a blue Toyota Yaris, a gray Toyota Yaris, and

a wine-colored Jeep Cherokee. The chase ended when the two Toyotas

crashed under a bridge.     The Jeep remained at a close distance.   A


                                   - 3 -
witness then heard two rounds of rapid gunfire.                   Thereafter, the

three co-defendants fled the scene in the Jeep Cherokee.

               Puerto Rico Police Department officers pursued the Jeep

until it eventually stopped near a pedestrian bridge in the nearby

city of San Juan.         At that point, the three defendants abandoned

the vehicle and fled on foot across the bridge to a housing

project.

               Cepeda    was     arrested       almost    immediately            in   the

third-floor hallway of one of the buildings in the housing project.

Law enforcement officers seized a pistol magazine that was found

nearby.       Officers also found and seized a bag of marijuana hidden

inside Cepeda's shoe.

               Tanco    and   Rosario   were     apprehended     in   an    apartment

within Building 46 of the housing project.                     The officers then

searched the apartment.            They found a pistol magazine under a

table,    a    pistol    frame   inside     a   laundry   bag,    and      two    pistol

magazines under a bed.           The slide and barrel of the pistol found

in the laundry bag were later found on either side of Building 46.

               Officers also found two Glock pistols beside the Jeep

Cherokee -- a model 17 and a model 27.               The latter model had been

modified to fire as a machinegun.               Multiple shell casings from the

scene of the shooting matched the three firearms seized in Building

46 and near the Jeep Cherokee.


                                            - 4 -
            On September 17, 2014, Tanco, Cepeda, and Rosario were

indicted in the District of Puerto Rico as co-defendants on a

number of federal firearms charges.           Cepeda was charged with

possession of firearms and ammunition by an unlawful user or addict

of a controlled substance, in violation of 18 U.S.C. § 922(g)(3)

(Count One); Tanco was charged with being a convicted felon in

possession of firearms and ammunition, in violation of 18 U.S.C.

§ 922(g)(1) (Count Two); Tanco, Cepeda, and Rosario were each

charged   with   aiding   and   abetting   each   other   in   the   illegal

possession of a machinegun, in violation of 18 U.S.C. § 922(o)

(Count Three).

            The three defendants proceeded to an eight-day jury

trial in late June 2015.         At trial, an expert testified that

Tanco's DNA was present on the steering wheel and stick shift of

the gray Yaris and a cigarette butt found in the driver's side of

that car.   The expert also testified that Rosario's DNA was found

on the steering wheel of the Jeep.

            A law enforcement agent testified at the trial as well.

He stated through an interpreter that Cepeda admitted to him in a

post-arrest interview that he had gone into a vehicle to smoke

marijuana that day, that he "smoked on a daily basis and that it

had been a long time since he had started," and that he possessed

the machinegun on the day of the events.


                                     - 5 -
           The government did not introduce into evidence a written

or recorded statement by Cepeda.      Nor did the government introduce

into evidence any notes that memorialized the law enforcement

agent's interview with Cepeda, which had taken place over a year

before trial.

           The jury returned guilty verdicts against each of the

defendants on all of the counts that each faced.           Cepeda filed a

motion for judgment of acquittal under Federal Rule of Criminal

Procedure 29 on Counts One and Three, Tanco filed a Rule 29 motion

on Counts Two and Three, and Rosario filed a Rule 29 motion on

Count Three.    The government opposed each Rule 29 motion, and the

District Court denied them all.

           On March 3, 2016, the District Court held sentencing

hearings for both Tanco and Cepeda.           Cepeda was sentenced to 120

months of imprisonment for his convictions on Counts One and Three,

to be served concurrently with one another.           Tanco was sentenced

to 120 months of imprisonment as to his convictions on Counts Two

and Three, also to be served concurrently.

           Rosario's sentencing hearing was held on April 18, 2016.

He   received   a   sentence   of   102   months'   imprisonment   on   his

conviction pursuant to Count Three.             The District Court also

imposed three-year terms of supervised release on all three co-

defendants for their convictions.


                                      - 6 -
             Tanco,    Cepeda,     and   Rosario   filed       timely   notices    of

appeal.    The consolidated appeals challenge:                 (1) the sufficiency

of   the   evidence     as   to   Cepeda's     conviction      on   Count   One   for

possession of firearms and ammunition by an unlawful user or addict

of a controlled substance, in violation of 18 U.S.C. § 922(g)(3);

(2) the sufficiency of the evidence for Tanco's conviction on Count

Two for being a convicted felon in possession of firearms and

ammunition,      in    violation    of   18    U.S.C.    § 922(g)(1);       (3)   the

sufficiency of the evidence for Tanco's and Rosario's convictions

on Count Three for aiding and abetting in the illegal possession

of a machinegun, in violation of 18 U.S.C. § 922(o); and (4) the

procedural and substantive reasonableness of Tanco's and Cepeda's

sentences.

                                         II.

             We begin by addressing the defendants' challenges to the

denial of their Rule 29 motions, in which the defendants take aim

at the sufficiency of the evidence supporting their convictions.

We review de novo the District Court's denial of a Rule 29 motion

that is based on a challenge to the sufficiency of the evidence to

support a conviction.         United States v. Cortes-Caban, 691 F.3d 1,

12 (1st Cir. 2012); United States v. Perez-Melendez, 599 F.3d 31,

40 (1st Cir. 2010).          We undertake such review by considering the

evidence    in   the    record     "in   the   light    most    favorable    to   the

prosecution" and by determining whether, considered in that light,
                                           - 7 -
the "body of proof, as a whole, has sufficient bite to ground a

reasoned conclusion that the government proved each of the elements

of the charged crime beyond a reasonable doubt."   United States v.

Lara, 181 F.3d 183, 200 (1st Cir. 1999).

                                A.

           We first consider Cepeda's challenge to the sufficiency

of the evidence for his conviction on Count One for violating 18

U.S.C. § 922(g)(3), which makes it "unlawful for any person . . .

who is an unlawful user of or addicted to any controlled substance

. . . to . . . possess in or affecting commerce, any firearm or

ammunition."   To establish the "unlawful user" element of this

offense, the government must prove beyond a reasonable doubt that

(1) the defendant used controlled substances regularly, (2) that

the use took place over a long period of time, and (3) that the

use was proximate to or contemporaneous with his possession of a

firearm.   See United States v. Caparotta, 676 F.3d 213, 216 (1st

Cir. 2012) (defining "unlawful user" under § 922(g)(3)); United

States v. Marceau, 554 F.3d 24, 30 (1st Cir. 2009) (same).

           Cepeda does not dispute that he possessed a firearm.   He

contends only that the evidence was insufficient to support a

finding that he was "an unlawful user of . . . any controlled

substance" within the meaning of § 922(g).    He alleges that the

only evidence in the record that could suffice to support that

finding is the testimony from the law enforcement officer who
                                 - 8 -
interviewed him that he admitted during that interview that he had

been a regular, long-term drug user.      Cepeda further contends that

this evidence cannot suffice to establish that he was an "unlawful

user," however, because, in his view, that admission was not

corroborated.

            The government agrees that the admission is necessary to

prove Cepeda's regular, long-term drug use and thus that he was an

"unlawful user."   The government further agrees that the admission

must be corroborated in order for it to be able to provide the

requisite   evidentiary   support   for   a   finding   that   he   was    an

"unlawful user," such that his conviction then could survive

Cepeda's    sufficiency-of-the-evidence       challenge.       But,       the

government contends, his challenge still lacks merit.

            The government asserts, first, that Cepeda failed to

contend in his Rule 29 motion that the admission concerning the

nature and duration of his drug use was not corroborated.             Thus,

the government contends, he has waived that ground for reversing

his conviction for lack of sufficient evidentiary support, or, at

least, he has forfeited that argument and cannot meet the demanding

plain error standard that applies in consequence.

            We do not agree.    In his written Rule 29 motion, in

addition to advancing various specific arguments, Cepeda made a

general sufficiency-of-the-evidence challenge, claiming that "the

government presented insufficient evidence at trial to support the
                                    - 9 -
elements of the offenses of which he was convicted."                         See United

States v. Foley, 783 F.3d 7, 12 (1st Cir. 2015) ("[A] general

sufficiency-of-the-evidence            objection      preserves        all     possible

sufficiency arguments."); United States v. Marston, 694 F.3d 131,

135 (1st Cir. 2012) ("There is good reason in case of doubt to

treat an ambiguous [Rule 29] motion . . . as 'general' in the sense

that it preserves all grounds.").            In that written motion, Cepeda

also   called     the   District      Court's   attention         to   the     lack    of

sufficient evidence to establish Cepeda's status as an unlawful

user, while stating that "Officer Concepcion's testimony that Mr.

Cepeda stated he had smoked marijuana 'for a long time' . . .

without more . . . could not have persuaded a rational trier of

fact   that    Mr.   Cepeda    was    an   unlawful    []    user      of    controlled

substances at the time of the charged offense."                        We know, too,

that the government asserted, in response to this motion, that the

evidence was sufficient to sustain the conviction, in part because

Cepeda's      "confession     was    corroborated     by    the   testimonial         and

ballistic evidence presented on trial."                    We therefore conclude

that this issue was not forfeited below.                    See United States v.

Valenzuela, 849 F.3d 477, 487 (1st Cir. 2017) ("Because this

argument was included in the defendant's original Rule 29 motion,

we undertake de novo review.").

              Alternatively, the government contends that even if

Cepeda preserved this challenge below, it lacks merit because the
                                           - 10 -
admission concerning his long-term drug use was corroborated.

But, here, too, we disagree.         To explain why, though, we need to

provide some background about the relevant legal precedents on the

weight     that   federal   courts    may   give   to    certain    types      of

incriminating statements by criminal defendants in assessing their

evidentiary sufficiency challenges to their convictions.             We begin

by describing those precedents.        We then explain why, in light of

them, the admission that is at issue was not corroborated and thus

cannot suffice to support the "unlawful user" element of the

offense for which Cepeda was convicted.

                                      1.

            "It is a settled principle of the administration of

criminal justice in the federal courts that a conviction must rest

upon firmer ground than the uncorroborated admission or confession

of the accused."     Wong Sun v. United States, 371 U.S. 471, 488-89

(1963).      This "corroboration rule" initially was intended to

mitigate    the   risk   that   a   false   confession   would     lead   to   a

conviction for a crime that not only had not been committed by the

defendant but also that had not been committed by anyone else.

See Smith v. United States, 348 U.S. 147, 153–54 (1954).

            That risk was evident from early English and American

cases.    Defendants in some of them had been sentenced to death for

homicide solely on the basis of their confessions of guilt, but

the supposed victims had then appeared, post-sentencing, "very
                                       - 11 -
much alive."     David A. Moran, In Defense of the Corpus Delicti

Rule, 64 Ohio St. L.J. 817, 826–31 (2003).

          Courts thus began, in cases involving an offense that,

like homicide, involved physical damage or injury, to demand

evidence independent of the defendant's confession of what is known

as the corpus delicti -- encompassing both an injury and a criminal

cause for that injury.       Only with such evidence could a confession

to that offense be considered corroborated.          And thus, only with

such evidence could a conviction be deemed adequately supported by

the evidence if the sufficiency of the proof depended upon the

confession.

          In this way, courts ensured that there would at least be

independent proof of a crime in place before the accused could be

convicted of committing it, even if there were no proof apart from

the defendant's confession of the defendant's culpability for that

crime.    So,    for   example,    under   this   corroboration    rule,   a

defendant's     confession    to   a   homicide   could   not   ground   the

conviction for that offense unless the government also put forth

adequate "tangible evidence of the death of the supposed victim."

Wong Sun, 371 U.S. at 489 n.15.

          But, while the corroboration rule initially served this

important but "extremely limited function," Smith, 348 U.S. at

153, the Supreme Court expanded on it in a trio of cases decided

on the same day in 1954.      See Smith, 348 U.S. 147;     Opper v. United
                                       - 12 -
States, 348 U.S. 84 (1954); United States v. Calderon, 348 U.S.

160    (1954).      In   so    elaborating      the    rule's    scope,    the   Court

broadened it in various ways, some of which have direct bearing on

the issues that are before us in this appeal.

            First, the Court explained in this trio of cases that,

although the corroboration rule was aimed at ensuring that a

defendant could not be convicted of committing a crime based simply

on his confession when no independent evidence indicated that a

crime had been committed at all, the rule also reflected broader

concerns    about    the      reliability      of   certain     statements    by   the

accused.    Specifically, the Court described the rule as reflecting

the fact that confessions may be unreliable because they are

coerced or induced or because, even if not involuntarily made,

they    might    "reflect       the   strain    and    confusion      attending    [an

accused's] predicament rather than a clear reflection of his past."

Smith, 348 U.S. at 153.               The Court further explained that the

requirement that a conviction for a crime like homicide must rest

on more than an uncorroborated confession by the accused reflects

the fact that the average juror is not familiar with the criminal

justice system's long history of false confessions.                    Id.

            These observations provided background for the Court's

clarification       in   this    trio   of     cases   that     the   scope   of   the

corroboration rule was not limited to "confessions."                      To be sure,

the Court explained, a confession is a "complete and conscious
                                          - 13 -
admission of guilt," Opper, 348 U.S. at 91, and the corroboration

rule historically had been applied to such confessions by the

accused. But, the Court held in these cases that the corroboration

rule was no less applicable to certain admissions by the accused,

even   though    such    statements       by    the    accused   are      not    like   a

confession because they fail to "admit[] to all the elements of

the offense," Smith, 348 U.S. at 154, and may merely "explain

actions rather than admit guilt," Opper, 348 U.S. at 91.

              The Court described the types of admissions to which the

corroboration rule applied as "statements of the accused out of

court that show essential elements of the crime . . . necessary to

supplement      an    otherwise      inadequate       basis    for   a    verdict       of

conviction."         Opper, 348 U.S. at 91.                 After all, the Court

elaborated, these "admissions have the same possibilities for

error as confessions."             Id.   Thus, the Court explained, when an

accused's "admission is made after the fact to an official charged

with   investigating         the    possibility        of    wrongdoing,        and   the

statement embraces an element vital to the Government's case," it

must be corroborated, just as a confession must be, to provide the

necessary evidentiary support to permit a conviction to survive a

sufficiency-of-the-evidence challenge.                 Smith, 348 U.S. at 155.

              The Court emphasized, moreover, that a statement by the

accused of the sort just described is subject to the corroboration

rule   even    when    the   admission     is    not    to    "one   of   the     formal
                                          - 14 -
'elements' of the crime" but instead only to "a fact subsidiary to

the proof of these 'elements,'" Smith, 348 U.S. at 155, that is

"essential" to the proof of an element, Opper, 348 U.S. at 90.

"It is the practical relation of the statement to the Government's

case which is crucial," the Court explained, "not its theoretical

relation to the definition of the offense."    Smith, 348 U.S. at

155.

           In light of this precedent, Cepeda's statement in his

interview with the law enforcement agent about the length and

nature of his drug use must be corroborated if it is to be relied

upon to support his conviction against the sufficiency-of-the-

evidence challenge that he brings.   For while that admission was

not a strict confession, it was made "after the fact to an official

charged with investigating the possibility of wrongdoing, and the

statement embrace[d] an element vital to the Government's case,"

id., given that the statement admits to a fact that is vital to

the government's effort to prove an element of the offense for

which he was convicted -- namely, the "unlawful user" element.

           Second, the Court in this trio of 1954 cases clarified

the corroboration rule in another respect that bears on Cepeda's

sufficiency-of-the-evidence   challenge.      This   clarification

concerned the types of offenses to which the corroboration rule

applied.


                                - 15 -
           The Court recognized that the corpus delicti for some

offenses -- unlike the corpus delicti for, say, homicide -- is not

"tangible."   Smith, 348 U.S. at 154.     For example, according to

the Court, tax evasion is an offense that lacks a "tangible" corpus

delicti, id., because the offense results in no "physical damage

to person or property," Wong Sun, 371 U.S. at 489 n.15.     The Court

then explained that, for offenses of that sort, evidence that would

tend to establish the corpus delicti "must implicate the accused,"

even though evidence that would tend to establish the corpus

delicti of offenses that result in physical damage or injury --

such as evidence of the murdered body in a homicide case -- need

not.   Smith, 348 U.S. at 154.

           The Court thus confronted a choice about whether to apply

the corroboration rule to this class of offenses.        As the Court

described that choice, it could either "apply[] the corroboration

rule to [these] offense[s] and accord[] the accused even greater

protection than the rule affords to a defendant in a homicide

prosecution, or . . . find[] the rule wholly inapplicable because

of the nature of the offense."   Id. (internal citations omitted).

           In the end, the Court chose the former path.     Id.   And,

it did so even though it recognized that it was thereby necessarily

providing a "broader guarantee" to defendants in cases of crimes

lacking a "tangible corpus delicti" than had been granted to

defendants accused of crimes that had one.         Id.     The Court
                                 - 16 -
explained that this "broader guarantee" resulted precisely because

the substantial independent evidence needed in such cases to

corroborate the admission or confession -- and thus to ensure that

a crime had been committed at all -- necessarily would also be

evidence "implicat[ing] the accused."     Id.

            The Court eventually summarized the corroboration rule

as it had been elaborated in this trio of 1954 cases in dicta as

follows: "[w]here the crime involves physical damage to person or

property, the prosecution must generally show that the injury for

which the accused confesses responsibility did in fact occur, and

that some person was criminally culpable."      Wong Sun, 371 U.S. at

489 n.15.   And, "in such a case," the Court went on, "[t]here need

. . . be no link, outside the confession, between the injury and

the accused who admits having inflicted it."     Id.; see also Smith,

348 U.S. at 153-54 (recognizing that for crimes producing physical

injuries, "[o]nce the existence of the crime was established . . .

the guilt of the accused could be based on his own otherwise

uncorroborated confession").

            But, by contrast, the Court further explained in that

dicta, "where the crime involves no tangible corpus delicti," then

"the corroborative evidence must implicate the accused in order to

show that a crime has been committed."    Wong Sun, 371 U.S. at 489

n.15 (second quotation quoting Smith, 348 U.S. at 154).      For, in

a case of that type, the only evidence that could corroborate the
                                 - 17 -
fact that a crime was committed at all -- according to the Court

-- is evidence that tends to prove that the defendant committed

it.     Smith, 348 U.S. at 154.       And so, the Court has made clear

that, at least in cases of that type, "[a]ll elements of the

offense    must     be   established     by     independent     evidence   or

corroborated admissions."        Id. at 156.

            The Court's guidance in the trio of 1954 cases about the

scope of the offenses to which the corroboration rule applies is

of direct relevance to Cepeda's sufficiency-based challenge to his

conviction.      That is so because the conviction that he challenges

under the corroboration rule is for a status-based, firearms

possession offense.      Thus, like the crime of tax evasion at issue

in Smith, it is a crime that has no "tangible corpus delicti."

Wong Sun, 371 U.S. at 489 n.15 (emphasis added) (citing Smith, 348

U.S. at 154).     In consequence, even though any evidence that would

tend to establish the corpus delicti for that offense "must

implicate" Cepeda in its commission, Smith, 348 U.S. at 154, the

government must corroborate the admission that he made about the

nature and duration of his drug use if it wishes to rely on that

admission to support the "unlawful user" element of the status-

based firearms possession offense of which he was convicted, see

id. at 154-56.

            Finally, the Court in this trio of cases addressed one

other    issue    that   bears   on   Cepeda's    evidentiary    sufficiency
                                       - 18 -
challenge to his conviction. That issue concerns the means through

which the government may corroborate an admission in a case in

which there is no tangible corpus delicti for the underlying

offense.

             Notably, the Court made clear in the trio of 1954 cases

that "the corroborative evidence [for the admission] need not be

sufficient, independent of the statements, to establish the corpus

delicti."     Opper, 348 U.S. at 93.       Thus, there is no requirement

for the government to put forth "substantial evidence . . . which

tends to establish the whole of the corpus delicti" directly.              Id.

(emphasis added).       For example, corroboration may be shown even if

the "direct corroborative evidence . . . tends to establish . . .

one element of the offense" and the other elements are proven

"entirely by independent evidence," so long as the evidence as a

whole, including any corroborated admissions, is "sufficient to

find guilt beyond a reasonable doubt."              Id. at 93-94 (emphasis

added).

             The Court also made clear that, while there must be

"substantial    independent     evidence     that   the   offense   has   been

committed," that substantial independent evidence may include

evidence that "merely fortifies the truth of the confession" or

admission.     Smith, 348 U.S. at 156.          Thus, evidence that would

not,   absent     the     confession    or      admission,   "independently

establish[] the crime charged," may nonetheless corroborate the
                                       - 19 -
admission or confession.          Id.    For that reason, the independent

evidence      that     corroborates   the   essential   fact   that   has   been

admitted may take the form of evidence that "bolster[s] the

[admission] itself and thereby prove[s] the offense 'through' the

statements of the accused."           Id. (emphasis added).

              The Court had no occasion in Opper, Smith, and Calderon

to address in full, however, the types of independent evidence

that could be relied upon to bolster such an admission, such that

the offense may be proved through that corroborated admission.

The Court was asked in each of those cases to find the admission

or confession at issue corroborated only based on evidence that

tended to show that the content of the relevant portions of the

admission or confessions was actually true, or that the alleged

crime had actually occurred.            Smith, 348 U.S. at 157-59; Opper,

348 U.S. at 93-94; Calderon, 348 U.S. at 164-168.               The Court had

no need, therefore, to address when or whether independent evidence

that directly tended to confirm only admitted facts other than the

"vital" fact in dispute could render trustworthy the admission of

that       essential     fact,   notwithstanding    the    absence     of    any

independent evidence that directly tended to establish it.1


       1In Smith, for instance, the government successfully
corroborated admissions of the defendant's net worth -- a key fact
in his prosecution for tax evasion -- both by "substantiating [his]
opening net worth directly" and by presenting "independent
evidence . . . which tends to establish the crime of tax evasion."

                                         - 20 -
          In Massei v. United States, however, we rejected the

notion that, under the corroboration rule as developed in the trio

of 1954 cases, the government could corroborate an admission

concerning such a vital fact merely through independent evidence

that corroborates a different fact that the accused had admitted,

regardless of the relation between that corroborated fact and the

vital one that was disputed.    241 F.2d 895, 904 (1st Cir. 1957),

aff'd, 355 U.S. 595 (1958).    Massei was a case about tax evasion,

and we held there that the defendant's admission that he had taken

in graft (which was alleged to be the source of his potentially

reportable income) was not sufficiently corroborated by "the fact

that [the defendant] was proved to have been a police officer as

stated in his admissions."    Id.   We explained that the independent



348 U.S. at 157-59. The government thus did not attempt to argue
that -- and, in consequence, the Court had no occasion to consider
whether -- the net worth admission was trustworthy because, for
example, other of his financial disclosures were shown to be
accurate.    Stating that corroboration can "prove the offense
'through' the statements of the accused," Smith, 348 U.S. at 156,
the Court cited by "cf." and without explanation to Parker v.
State, 88 N.E.2d 556 (Ind. 1949), reh'g denied, 89 N.E.2d 442 (Ind.
1950), in which the Indiana Supreme Court held that "the
corroboration required is not of incidental facts stated in the
confession but that the offense charged had been committed."
Parker, 88 N.E.2d at 558. In other words, the corroboration could
not merely tend to support the credibility of the confession if it
did not also tend to show the existence of a crime. Id. at 559-
60.




                                    - 21 -
evidence that tended to establish the police officer aspect of the

defendant's admission "f[ell] short of . . . corroboration" of the

admission that concerned his taking in graft, as there was no

"evidence of actual graft taking or opportunity for such."   Id.2

          Nor do we understand our most recent decision in United

States v. Singleterry to require us to take a contrary approach to

the corroboration rule than the one Massei took.   See 29 F.3d 733

(1st Cir. 1994).     In Singleterry, we considered a sufficiency

challenge by a defendant who had admitted to, and been convicted

of, carrying a gun in connection with a drug trafficking offense.

Id. at 735-36.   Without mentioning Massei, we stated in a footnote

that, "in the absence of independent evidence of the corpus

delicti," an admission may be corroborated by "other evidence

typically used to bolster the credibility and reliability of an

out-of-court statement."    Id. at 737 n.3.   We further concluded

-- in dicta in a separate footnote -- that corroborated evidence

of the defendant's admitted drug trafficking was "strong evidence"




     2 Upon appeal, the Supreme Court rejected our contention that
what the graft admission was introduced to demonstrate -- the
"likely source" of the defendant's increased net worth -- was an
"indispensable element" of the crime of tax evasion under the net
worth method of proving evasion, as the government could
alternatively demonstrate that no possible source of nontaxable
income existed. United States v. Massei, 355 U.S. 595, 595 (1958).
Nevertheless, the Court affirmed without disagreeing with our
discussion of what would be required to corroborate that admission.
Id.
                                 - 22 -
of the trustworthiness of the defendant's further admission that

he had used a firearm that had been found in connection with the

trafficking.      Id. at 738 n.5.

             But, we do not understand that conclusion concerning two

types of conduct that have long been thought to be associated with

one another -- drug trafficking and firearms usage in furtherance

of the trafficking        -- to suggest that Massei erred in declining

to   treat    a   corroborated      admission     as    necessarily   rendering

trustworthy an unrelated one not otherwise corroborated.                      The

Court has noted that questions of corroboration are necessarily

fact-dependent,     see    Opper,    348   U.S.    at    93,   and,   given   the

particular facts at issue in Singleterry, and the oft-remarked-

upon connection between firearms and drug trafficking, see, e.g.,

United States v. Bianco, 922 F.2d 910, 912 (1st Cir. 1991) ("[W]e

often observe that firearms are common tools of the drug trade

. . . ."), we do not read the dicta in Singleterry to hold that

independent evidence that tends to establish a fact that has been

admitted renders trustworthy all other facts admitted by the

accused, no matter how unrelated to each other they may be, even

though no independent evidence tends to establish those facts

directly.     See also United States v. Deville, 278 F.3d 500, 506-

07 (5th Cir. 2002) (finding a defendant's admission to carrying a

gun in connection with drug trafficking corroborated by extensive

evidence that the defendant engaged in drug trafficking); cf.
                                        - 23 -
United States v. Brown, 617 F.3d 857, 863 (6th Cir. 2010) (deeming

a defendant's admission to committing a burglary and possessing a

gun stolen in that burglary corroborated by independent evidence

that the gun was stolen in that burglary).

            Indeed, we note that, in accord with Massei, other

circuits have declined to apply the corroboration rule in such a

mechanical fashion, whereby independent evidence that tends to

establish    a   fact    in   an   accused's       admission    may   suffice    to

corroborate an otherwise unrelated vital fact that the admission

also contains on the theory that the defendant's corroborated

admissions permit the conclusion that he is generally reliable.

See United States v. Stephens, 482 F.3d 669, 673 (4th Cir. 2007)

(finding a defendant's confession uncorroborated despite testimony

demonstrating that a person described in the confession existed

and owned the car described by the defendant); United States v.

Calhoun, No. 92-2001, 1993 WL 280324 at *3 (6th Cir. July 26, 1993)

(per curiam) ("Nor do we believe that the fact the other crimes

admitted to in the confession are corroborated permits the use of

the confession to prove an uncorroborated crime."); United States

v. Lopez-Alvarez, 970 F.2d 583, 595 (9th Cir. 1992) (holding that

a defendant's admission that he helped a murderer avoid capture at

an airport was uncorroborated where "[t]he only elements of [it]

that have been independently verified are those relating to his

presence    at   the    airport"    and    rejecting    as     insufficient     the
                                          - 24 -
government's     evidence        that   other      unrelated   admissions     of   the

defendant "appear[ed] trustworthy").

             This guidance about the means by which admissions may be

corroborated         directly    bears       on    Cepeda's    case,    because    the

government does not contend that substantial independent evidence

directly corroborates all parts of his admission.                      The government

does argue that we may treat the evidence in the record of Cepeda's

recent drug possession -- namely, the drugs found in his shoe on

the day of his arrest -- as corroborative of his admission of his

recent   drug    use,        although   we    note    that    the   caselaw   is   not

consistent      in     its    treatment       of    whether    such    evidence    can

corroborate such an admission.               Compare United States v. Sperling,

400 F. App'x 765, 768 (4th Cir. 2010) (concluding that a canine

alert may have provided some evidence of drug possession but did

not sufficiently corroborate a defendant's admission that he was

an unlawful user), with United States v. Mashore, 346 F. App'x

934, 935 (4th Cir. 2009) (per curiam) ("[T]he strong odor of

marijuana that [a police officer] observed while standing outside

[the defendant's] vehicle . . . was sufficient to justify an

inference by the fact-finder that [his] confession about his

marijuana use was true.").3



     3 We do not endorse Sperling's suggestion that evidence of
drug possession "is quite irrelevant to the issue of drug use."
400 F. App'x at 768.
                                             - 25 -
              But, the government does not argue that there is any

independent evidence in the record that in and of itself tends to

establish that he was a long-term drug user, as the government has

sometimes offered in other cases in which courts have found

admissions that pertain to the "unlawful user" element to have

been corroborated.      See, e.g., United States v. Dalhouse, 534 F.3d

803, 807 (7th Cir. 2008) (finding an "unlawful user" admission

corroborated by witness testimony that the defendant was a long-

term user).      But see United States v. Soltani, 360 F. App'x 694,

696 (8th Cir. 2010) (concluding, without significant explanation,

that evidence relating only to recent use corroborated a confession

to being a regular, long-term user); Mashore, 346 F. App'x at 935-

36 (similar).        Notably, for example, the government conceded at

oral argument that the marijuana found on Cepeda did not directly

tend to establish the length of his drug use.

              Instead, the government seeks to fortify the reliability

of Cepeda's statement concerning the nature and duration of his

past   drug    use   solely    by    pointing    to   evidence   that   provides

independent support for finding the content of other statements

that   Cepeda    offered      in    the   same   twenty-to-twenty-five-minute

interview to be true.         In addition to his admission to drug use on

the day of the offense, Cepeda stated that he was present in the

gray Yaris during the shootout, that his escape was into the Jeep,

and that he possessed an automatic weapon and concealed a pistol
                                          - 26 -
magazine.    The government asserts -- and Cepeda does not dispute

-- that substantial independent evidence does tend to establish,

in and of itself, each of those statements.                The government then

further asserts that, in consequence, we may treat his admission

concerning the regular and long-term nature of his drug use as

reliable, given that the reliability of his other statements has

been adequately demonstrated even though it does not argue that

any of the evidence that corroborates those admissions constitutes

evidence that in and of itself tends to establish that Cepeda was

a long-term user of drugs.

            Thus,   we      now   consider      the    record      evidence      of

corroboration and the government's case that it suffices here.                  In

doing so, we emphasize that the need for there to be substantial

independent evidence to corroborate Cepeda's admission bearing on

his status as an "unlawful user" is particularly clear, because

the   circumstances    in   which    Cepeda   is   said     to   have   made    the

admission bear strong "indicia of unreliability."                Smith, 348 U.S.

at 159.

            Cepeda's     statement    pertained       to   the   most   disputed

element of the crime, the length of time he had used drugs.                    That

element is also one that is unusually difficult to prove absent an

admission, as it requires evidence of regular illegal activity

over a long period of time. In addition, the interview with Cepeda

in which he made the admission was not videotaped or recorded.
                                       - 27 -
Nor were any supporting notes of the interview submitted. Instead,

one of his interviewers, Homeland Security Investigations Task

Force Agent Carlos Concepcíon-Ramos ("Concepcíon"), testified at

trial based solely on his memory of Cepeda's statements. Moreover,

while Concepcíon testified that he understood Cepeda to have

admitted to being an unlawful user, his testimony revealed that

Cepeda's actual words -- "hacía tiempo" -- are susceptible to

multiple understandings, some of which would not clearly establish

the length of Cepeda's drug usage.       See Calderon, 348 U.S. at 164

(carefully scrutinizing an admission for corroboration where the

meaning of an "oral statement" at issue was "certainly not clear").

                                   2.

          We begin with the independent evidence in this case that

corroborates Cepeda's admissions concerning the vehicles he was in

during the shootout.    We do not see how this independent evidence

concerning the day of his arrest suffices to corroborate Cepeda's

admission that he regularly used drugs over a long period of time.

There is too little relationship between the admitted fact that is

directly confirmed by independent evidence and the admitted fact

for which there is none. And, the absence of any such relationship

is   especially    problematic    given       the   strong    indicia    of

unreliability present here.

          For     similar   reasons,     we    conclude   that     Cepeda's

admissions   concerning     firearms    do    not   require   a   different
                                   - 28 -
conclusion.        For while those admissions are also confirmed by

independent evidence, as Cepeda himself accepts, his connection to

firearms bears no relationship to any past, regular drug use on

his part.    Nor does the government contend otherwise.                   This is not

a case, for example, like Singleterry in which the admissions --

corroborated and uncorroborated, respectively -- concern conduct

that has a well-known relationship.                  For while a corroborated

admission    of    being   a   drug      trafficker       may   suffice       to   render

trustworthy an uncorroborated admission of using a firearm to carry

out   that   unlawful      trade,     there   is     no    similarly      established

connection    between      regular       long-term    drug      use     and    firearms

possession.       Nor does the government argue otherwise.

             Of course, Cepeda did also admit to recent drug use, as

he admitted to using marijuana on the day of his arrest.                             But,

even if we were to treat that admission concerning recent drug use

as if it were corroborated by the evidence of his recent drug

possession, as would seem plausible, but see Sperling, 400 F. App'x

at 768 (finding that evidence of current possession does not

corroborate       an   admission    of    recent     use),      there    is    still   a

substantial temporal gap between the conduct admitted to in his

statement about his recent use of drugs and the conduct admitted

to in his statement about whether he was a regular, long-term user,

cf. Calderon, 348 U.S. at 164 (holding that evidence that the

defendant was poor at one point in time was "too remote" to
                                           - 29 -
corroborate an admission relating to his wealth a decade later).

Without purporting to identify precisely how long such drug use

must have occurred to qualify, we note that the government points

us to authority finding a defendant to have been an "unlawful user"

only on the basis of evidence that he had used drugs for at least

a year.     See United States v. Burchard, 580 F.3d 341, 352-54 (6th

Cir.   2009)      (affirming    a   conviction      under      § 922(g)(3)    where

evidence showed the defendant had used cocaine over a one-year

period).

             Moreover, we emphasize, the government conceded at oral

argument that it is not contending that the evidence of Cepeda's

recent drug use in and of itself tends to establish that he used

drugs over the extended period of time required by the statute.

Rather, the government argues only that the evidence corroborating

that admission about recent drug use, along with the evidence

corroborating Cepeda's other admissions unrelated to his admission

concerning     his   past    drug     use,   suffices     to    corroborate       that

admission    by    revealing    him    to    be   generally     reliable     in   his

admissions.       See United States v. Jones, 232 F. Supp. 2d 618, 622

(E.D. Va. 2002) (finding a defendant's admission to being an

"unlawful      user"        uncorroborated        where        the   government's

corroboration merely verified "peripheral facts unrelated to the

crime in prosecution").


                                         - 30 -
          Nor do we see how the fact that independent evidence

corroborates   each   of   these   various    admissions    --   concerning,

respectively, the cars that Cepeda was in during the shootout, the

firearms that he possessed during it, and his recent drug use

-- requires a different conclusion.           The government provides us

with no argument as to why the confirmation of any of these

admissions   is   particularly     probative    of   the   key   unconfirmed

admission to being a regular, long-term user.              Thus, even when

considered together, the government advances no argument as to why

there is more than a remote relationship between these corroborated

facts and the "essential" fact that is in dispute: whether Cepeda

was a long-term, regular drug user, given that such conduct

necessarily had to occur well before the shootout.                 Yet, the

precedent is clear that each essential fact that is admitted must

be corroborated in order for the offense to be proved through the

admission of such a fact.

          We emphasize, again, that the interview in which the

defendant made the critical admission was not documented at all in

the two years prior to trial and the admission itself was unusually

ambiguous as to a key element of the offense.          The jury therefore

had no basis to make an independent assessment of the conditions

and context under which Cepeda admitted to being a regular, long-

term drug user and therefore no basis to conclude that Cepeda's

admission was untainted by pressure or coercion.                 If Cepeda's
                                     - 31 -
admission had fewer indicia of unreliability, then the jury might

have had a greater ability to assess the admission's credibility.

There thus might in such circumstances be a correspondingly lesser

amount of corroboration required on sufficiency review.

             Thus, mindful of these indicia of reliability and that

"[e]ach case has its own facts admitted and its own corroborative

evidence,"        Opper, 348 U.S. at 93; see also Smith, 348 U.S. at 156

(recognizing "differing views on the substantiality of specific

independent evidence"), we conclude that the evidence that the

government        identified   as   sufficient     to   corroborate   Cepeda's

statement that he had used drugs over a long period of time is not

adequate     to    do   so.    Accordingly,   we    conclude   that   Cepeda's

conviction on Count One rested on an uncorroborated admission and

thus must be reversed because it is not supported by sufficient

evidence.4

                                       B.

             We next consider Tanco's challenge to his § 922(g)(1)

conviction.        Under 18 U.S.C. § 922(g)(1), it is "unlawful for any

person . . . who has been convicted in any court of, a crime




     4 Cepeda also asserts that the government's evidence, even if
sufficiently corroborated, does not establish that his drug use
took place over a long period of time. Because we resolve the
first argument in his favor, we need not address the second.
                                        - 32 -
punishable by imprisonment for a term exceeding one year . . . to

. . . possess in or affecting commerce, any firearm or ammunition."

           Tanco stipulated that he was a felon.              He challenges

only the possession element of the offense.            "Possession can be

either actual or constructive, sole or joint."              United States v.

Wight,   968   F.2d   1393,   1397   (1st   Cir.   1992).      "Constructive

possession of a firearm may be established when a person 'knowingly

has the power and intention at a given time of exercising dominion

and control over [it] either directly or through others.'"            United

States v. Ridolfi, 768 F.3d 57, 61-62 (1st Cir. 2014) (quoting

United States v. McLean, 409 F.3d 492, 501 (1st Cir. 2005)).

           Constructive possession can be inferred, moreover, from

circumstances "such as a defendant's control over the area where

the contraband is found (e.g., defendant's home or automobile)."

Id. at 62 (quoting McLean, 409 F.3d at 501).           Thus, constructive

possession may be proven "through the use of either direct or

circumstantial evidence; however, mere presence or association

with another who possessed the contraband is insufficient to

establish constructive possession."         Wight, 968 F.2d at 1397.     Put

otherwise, "there must be some action, some word, or some conduct

that links the individual to the contraband and indicates that he

had some stake in it, some power over it."            McLean, 409 F.3d at

501 (alterations and internal quotations omitted).


                                      - 33 -
            Tanco contends that there was insufficient evidence of

either his actual or his constructive possession of a firearm.           We

disagree.

            The evidence supportably shows that Tanco was involved

in a drive-by shooting and that, during it, he was driving the

gray Yaris that was involved in that shooting.         The evidence also

supportably shows both that he was in an apartment where officers

found a pistol in a laundry bag and a pistol magazine under the

table and that two other firearms were found near the Jeep from

which he and his co-defendants exited during the police chase.

Furthermore, the evidence suffices to show that shell casings from

each of these three firearms were found at the site of the

shooting.

            Viewing the evidence in the light most favorable to the

verdict, a jury could reasonably find that all three firearms were

used during the shooting.         The evidence concerning the shell

casings,    when   considered   with    other   evidence   just   reviewed,

suffices to establish as much.           Given that the evidence also

supportably shows that Tanco participated in the entirety of the

drive-by shooting and police chase along with the other two co-

defendants, the evidence suffices to permit a reasonable jury to

find that he had or could have exercised control over at least one

of the three firearms during the course of those events.                See

Wight, 968 F.2d at 1398 (finding that "it could be inferred from
                                       - 34 -
[the] fact" that the defendant was in the vehicle for the purpose

of committing a crime that "he, as a convicted felon, exercised

joint dominion or control over the vehicle and its contents,

including the firearm").       Therefore, we affirm Tanco's conviction

on Count Two.

                                     C.

           We next turn to Tanco's and Rosario's challenges to their

§ 922(o) convictions of aiding and abetting in the possession of

a machinegun.    On appeal, Cepeda does not contest his conviction

as to Count Three.     Therefore, we affirm.

           Under 18 U.S.C. § 922(o), it is "unlawful for any person

to   transfer   or   possess   a   machinegun,"   setting   aside   certain

enumerated exceptions that do not apply here.               To establish a

violation of § 922(o), "the government must prove that 1) the

defendant possessed or transferred a machinegun 2) with knowledge

that the weapon had the characteristics to bring it within the

statutory definition of a machinegun."         United States v. Olofson,

563 F.3d 652, 659 (7th Cir. 2009).        "A machine gun is defined as

'any weapon which shoots, is designed to shoot, or can be readily

restored to shoot, automatically more than one shot, without manual

reloading, by a single function of the trigger.'"            United States

v. Nieves-Castano, 480 F.3d 597, 599 (1st Cir. 2007) (quoting 26

U.S.C. § 5845(b)).


                                      - 35 -
            With regard to the knowledge requirement, the government

must prove that "the defendant had knowledge of the characteristics

that brought the gun within the statutory definition, and not that

[]he had knowledge that the gun was in fact considered a machine

gun under law."         Id.    "The requisite mens rea may be established

by circumstantial evidence," which includes "external indications

signaling the nature of the weapon."               Id. at 601 (quoting Staples

v. United States, 511 U.S. 600, 615 n.11 (1994)).

            At trial, the District Court instructed the jury, with

respect to this offense, about aiding and abetting liability.

"Aiding    and     abetting      requires     that    'the     defendant    [have]

associated himself with the venture, participated in it as in

something he wished to bring about, and sought by his actions to

make it succeed.'"            United States v. Luciano-Mosquera, 63 F.3d

1142, 1149–50 (1st Cir. 1995) (alteration in original) (quoting

United    States   v.    Alvarez, 987       F.2d    77,   83   (1st   Cir.), cert.

denied, 510      U.S.    849    (1993)).      "Mere       association   with     the

principal, or mere presence at the scene of a crime, even when

combined with knowledge that a crime will be committed, is not

sufficient to establish aiding and abetting liability."                    Id.   at

1150.

            The Supreme Court has held that aiding and abetting

liability requires the government to show that the defendant had

"advance knowledge" of the elements of the offense.                   Rosemond v.
                                           - 36 -
United States, 572 U.S. 65, 78 (2014).    Advance knowledge "means

knowledge at a time the accomplice can do something with it --

most notably, opt to walk away."      Id.; see United States v.

Rodríguez-Martinez, 778 F.3d 367, 371 (1st Cir. 2015).

          The government contends that the evidence sufficed to

show that Tanco and Rosario aided and abetted Cepeda's possession

of the machinegun, given the evidence that showed their joint

involvement in the drive-by shooting and Cepeda's admission that

he possessed the machinegun during that incident.        Tanco and

Rosario, however, argue that the government failed to prove that

they had advance knowledge of the characteristics of the machinegun

and thus that the evidence did not suffice to establish that they

aided and abetted Cepeda in the possession of the machinegun.   We

are not persuaded.

          It is true that the government presented no evidence

that Tanco and Rosario knew of the pistol's machinegun capabilities

until the point at which Cepeda began firing.   But, the government

did introduce evidence from which a jury could reasonably find

that Tanco and Rosario were with Cepeda during the drive-by

shooting and that they each heard a rapid round of shots being

fired that was consistent with the firing of a machinegun.   Taking

the evidence of the rapid firing of the machinegun in the light

most favorable to the verdict, a jury could reasonably find beyond

a reasonable doubt that Tanco and Rosario knew that the pistol
                                - 37 -
that was being fired was a machinegun.         See Staples, 511 U.S. at

615   n.11    ("[K]nowledge    can   be   inferred    from   circumstantial

evidence, including any external indications signaling the nature

of the weapon.    And firing a fully automatic weapon would make the

regulated characteristics of the weapon immediately apparent to

its owner.").

             Thus, the only question is whether Tanco and Rosario had

a "realistic opportunity to quit the crime" after the point at

which the jury could reasonably find that they knew the pistol was

a machinegun.     United States v. Manso-Cepeda, 810 F.3d 846, 849

(1st Cir. 2016) (internal quotations omitted).            For, if they did

not have such an opportunity, then         "the defendant has not shown

the requisite intent to assist a crime involving a gun."                Id.

(internal quotations omitted).

             The Supreme Court has made clear that "if a defendant

continues to participate in a crime after a gun was displayed or

used by a confederate, the jury can permissibly infer from his

failure to object or withdraw that he had such knowledge.           In any

criminal case, after all, the factfinder can draw inferences about

a defendant's intent based on all the facts and circumstances of

a crime's commission."        Rosemond, 572 U.S. at 78 n.9.      Tanco and

Rosario "do[] not adequately explain why it was too late to

withdraw."     Manso-Cepeda, 810 F.3d at 851.        Thus, they have failed


                                      - 38 -
to provide a basis for overturning their convictions for violating

§ 922(o) on sufficiency grounds.5

                                    III.

             Finally, we address the reasonableness of Cepeda's and

Tanco's challenges to their sentences.           Cepeda and Tanco both

challenge the procedural and substantive reasonableness of their

sentences.

             Our first task is to determine whether the District Court

made any procedural errors "such as failing to calculate (or

improperly     calculating)   the   Guidelines   range,   treating   the

Guidelines as mandatory, failing to consider the [18 U.S.C.]

§ 3553(a) factors, selecting a sentence based on clearly erroneous




     5 Rosario also argues for the first time on appeal that the
jury instructions related to illegal possession were erroneous
because they "failed to require that Rosario[] knew in advance
that one of his codefendants would be armed."      The government
argues that any such argument is waived because Rosario neither
raised an objection to the instructions below nor adequately
developed his argument on appeal. See United States v. Soto, 799
F.3d 68, 96 (1st Cir. 2015); United States v. Zannino, 895 F.2d 1,
17 (1st Cir. 1990). In any event, Rosario's argument has no merit,
because the jury instructions specifically required "that the
charged defendants consciously shared advance knowledge of the
person's possession of the machine gun and advance knowledge of
the characteristic that made the weapon a machine gun, intended to
help each other, and took part in the endeavor seeking to make it
succeed." (Emphasis added); see Rosemond v. United States, 572
U.S. 65, 78 (2014) (holding that "advance knowledge" is "knowledge
that enables [the defendant] to make the relevant legal (and
indeed, moral) choice," including to "withdraw from the
enterprise").

                                     - 39 -
facts, or failing to adequately explain the chosen sentence --

including an explanation for any deviation from the Guidelines

range." Gall v. United States, 552 U.S. 38, 51 (2007). Generally,

procedural errors in sentencing are reviewed for an abuse of

discretion.   United States v. Dávila-González, 595 F.3d 42, 47

(1st Cir. 2010). If there are no procedural errors, we then review

the substantive reasonableness of the sentence for an abuse of

discretion.   United States v. Pantojas-Cruz, 800 F.3d 54, 58-59

(1st Cir. 2015).6

                                A.

          We begin by reviewing what happened at sentencing.    We

start by reviewing the pre-sentence reports ("PSRs") that the

United States Probation Officer prepared for Tanco and Cepeda's

cases.

          Tanco's and Cepeda's PSRs highlighted that, on the date

of the events in question, gunfire was heard by witnesses and the

two defendants "were seen leaving the scene in a wine Jeep Cherokee

where the body of Juan R. Delgado-Rodríguez was found."    Because




     6 The government asserts that because Tanco did not argue that
the 120-month prison sentence was substantively unreasonable after
it was imposed, we should review on plain error. However, "the
applicable standard of review for an unpreserved, substantive
reasonableness challenge is murky." United States v. Arsenault,
833 F.3d 24, 29 (1st Cir. 2016)(internal quotations omitted).
Thus, we will apply the more defendant-friendly abuse of discretion
standard of review.
                                - 40 -
the PSRs concluded that Cepeda and Tanco had committed their

firearms crimes in connection with the murder of Delgado, the PSRs

recommended a base offense level ("BOL") of 43 for first degree

murder     under    U.S.S.G.    § 2A1.1,     as    U.S.S.G.     § 2K2.1(c)(1)(B)

requires the application of the most analogous homicide cross-

reference if firearms or ammunition were used or possessed in

connection with a death.

             Cepeda had a Criminal History Category ("CHC") of I and

Tanco had a CHC of II.         The PSRs accordingly calculated that the

guidelines    would       recommend   a    sentence     of   life   imprisonment.

However, 18 U.S.C. §§ 922(g)(1), 922(g)(3), and 922(o) do not carry

life sentences.       See 18 U.S.C. § 924(a)(2).             The PSRs therefore

recommended a guidelines range of the statutory maximum prison

sentence: 120 months', or 10 years', imprisonment as to both Tanco

and Cepeda.

             Cepeda and Tanco objected to the PSRs' application of

the murder cross-reference.           The defendants each pointed to an

alleged lack of evidence to support its application.                  After all,

they noted, the District Court expressly prohibited any discussion

of   the   murder    of    Delgado,   as    it    was   being   handled   in   the

Commonwealth's local courts.

             Absent the application of the murder cross-reference,

Cepeda and Tanco argued, the proper BOL for each of them under

U.S.S.G. § 2K2.1(a)(4)(B) was 20, because their offenses involved
                                          - 41 -
a machinegun and because, according to the jury verdict, they were

prohibited persons at the time of the offense under § 922(g)(3)

and § 922(g)(1), respectively.7              Tanco argued that, with a BOL of

20 and a CHC of II, his sentencing range should be 37-to-46 months’

imprisonment.         Cepeda argued that with a CHC of I and a BOL of 20,

his guidelines range was 33-to-41 months’ imprisonment.

                At the sentencing proceeding, the District Court made a

number of findings regarding Cepeda and Tanco's participation in

the murder of Delgado.               The District Court correctly determined

that it needed only to find by a preponderance of the evidence

that they had participated in that murder in order to apply the

murder cross-reference.              See United States v. Rodriguez-Reyes, 714

F.3d 1, 11-14 (1st Cir. 2013).               Nevertheless, the District Court

declined to apply the murder cross-reference and the BOL of 43

that would have applied in consequence.

                Instead, the District Court agreed with Tanco and Cepeda

that       a   BOL   of   20   was   appropriate.    The   Court's   calculation

reflected not only the fact that Cepeda and Tanco were convicted

of offenses involving a machinegun, which would have resulted in

only a BOL of 18 under U.S.S.G. § 2K2.1(a)(5), but also that they

were both determined to be prohibited persons, which increased



       7
       The guidelines define "prohibited person" for the purposes
of U.S.S.G. § 2K2.1 as "any person described in 18 U.S.C. § 922(g)
or § 922(n)." U.S.S.G. § 2K2.1 cmt. n.3.
                                            - 42 -
their BOLs to 20 under U.S.S.G. § 2K2.1(a)(4)(B).       The Court then

proceeded to apply an additional two-level enhancement pursuant to

U.S.S.G. § 2K2.1(b)(1)(A), because their offenses involved three

or more firearms, for a total offense level ("TOL") of 22. Because

neither Cepeda's nor Tanco's requested guidelines calculations

reflected this enhancement for multiple firearms, the District

Court arrived at higher guidelines ranges than those argued for by

the defendants: 41-to-51 months' imprisonment for Cepeda and 46-

to-57 months' imprisonment for Tanco.

          The   District   Court   first    sentenced   Cepeda.     It

considered a variety of sentencing factors, including his age,

education, and use of marijuana.    Regarding Cepeda's participation

in the shooting, the District Court concluded that Cepeda had been

in the car that had been following the victim and that shots were

fired by someone in that car.        The District Court could not

determine, however, that Cepeda himself had used a firearm, as it

could have been Tanco who fired the shots.

          After reviewing the § 3553(a) factors, including the

"need for the sentence imposed . . . to protect the public from

further crimes of the defendant," see 18 U.S.C. § 3553(a)(2)(C),

the District Court imposed a sentence of 120 months of imprisonment

each for Counts One and Three -- an upward variance from the

guidelines range to the maximum sentence allowed under the statute

-- to be served concurrently.      In support of the variance, the
                                   - 43 -
District Court noted its finding that Cepeda had participated in

the killing of Delgado.       The Court found that the killing was

preplanned because the high-speed chase appeared to be highly

orchestrated and involved two people -- Cepeda and Tanco -- in the

gray Yaris, as well as a third person in the Jeep.             The District

Court also took note of a cell phone seized near the abandoned

Jeep that contained a text message describing someone as being

"alone," wearing a black sweater, and having a "spider web tattoo

on his hand."

            The government suggested that the message supported an

inference that the shooting was preplanned because the description

in the text message matched Delgado's appearance on the day of the

shooting.    Although it was unclear to whom the phone belonged or

whether Cepeda or Tanco had sent or received the message, the

District Court, after considering the § 3553(a) factors, stated

that the text message did provide support as to the co-defendants'

premeditation to kill the victim, as the message identifying

Delgado   and   claiming   that   he    was     alone   suggested   that   the

defendants were implementing a plan to commit a murder that had

been arranged in advance.

            Cepeda objected to the sentence as procedurally and

substantively unreasonable.       He emphasized that it was more than

two times greater than the highest end of the guidelines range and

that there was a lack of evidence to establish premeditation or
                                       - 44 -
mens rea.    The District Court disagreed and noted that Cepeda was

one of the three people who exited the Jeep after the police chase

and that he was found with a loaded magazine nearby.

             The District Court next sentenced Tanco.           After hearing

about and considering his education level, his upbringing in a

dangerous area, and his obligations to his wife and his young

children, the Court then decided to apply the same upward variance

for Tanco that it had applied for Cepeda because the use of the

weapons for which Tanco was being charged resulted in a death.             In

arriving at that conclusion, the District Court made similar

findings as it did in Cepeda's case, noting as well that Tanco's

DNA had been found in the Yaris and that Tanco was eventually found

in an apartment where part of a firearm was seized.

                                     B.

             With that background in place, we first address Tanco's

sentencing    challenge.     Tanco   argues      that   the   District   Court

committed    procedural    error   by     "circumventing      the   applicable

guidelines range and fail[ing] to justify the extent of [its]

upward variance."      Specifically, he contends that the District

Court erred in relying on a determination that he was involved in

Delgado's murder for the upward variance, that his sentence was

imposed   without   the    protections     afforded     by    the   sentencing

guidelines, and that the District Court failed to consider his


                                        - 45 -
mitigating      factors.         He       also   challenges    the     substantive

reasonableness of the sentence.

                                           1.

             With     respect   to    Tanco's     challenge    to    the    District

Court's consideration of his role in the Delgado murder, the

District Court did not find that Tanco committed it. Rather, based

on the evidence presented at trial and at sentencing, the District

Court found by a preponderance of the evidence that the firearms

underlying Tanco and his co-defendants' federal charges were used

to kill Delgado, that Tanco was at least associated with the

murder, and that the killing was preplanned.

             The District Court did not err in doing so.                        Prior

criminal conduct is part of the history and characteristics of the

defendant that may be considered at sentencing, see 18 U.S.C.

§§ 3553(a)(1), 3661, and may be relevant in particular cases to

the   factors       enumerated       in    § 3553(a)(2).        In     making       its

determination about the sentence to be imposed, moreover, "[a]

sentencing court is entitled to rely on circumstantial evidence

and   draw   plausible     inferences        therefrom."      United       States   v.

Marceau, 554 F.3d 24, 32 (1st Cir. 2009) (internal citations

omitted).       The    phone    found     next   to   the   Jeep,    for   instance,

identified someone resembling the victim, thereby giving rise to

the inference that the defendants -- who had recently abandoned

that same Jeep -- planned and executed the murder.                         Thus, the
                                            - 46 -
District Court acted permissibly in giving weight to the evidence

concerning the Delgado murder, see United States v. Overstreet,

713 F.3d 627, 638 (11th Cir. 2013) (affirming an above-guideline

sentence because the District Court found that the defendant had

committed a murder connected to the offense), even though it did

not apply the murder cross-reference.

               In addition, because the District Court expressly made

its findings with respect to Tanco's relationship to that murder

under a preponderance of the evidence standard, Tanco's argument

that he was sentenced without the procedural protections of the

guidelines has no merit.8         See United States v. Damon, 595 F.3d

395, 399 (1st Cir. 2010) (holding the government "must show the

facts       supporting   an   enhancement   by   a   preponderance   of   the

evidence").

               Finally, contrary to Tanco's contention, the District

Court did address his mitigating factors.            Although Tanco may not

agree with the District Court's weighing of the § 3553(a) factors,

"[w]eighing of those factors is left largely within a sentencing

court's discretion."          United States v. Gonzalez-Rodriguez, 859

F.3d 134, 140 (1st Cir. 2017).        And while a sentencing court must

consider the applicable § 3553(a) factors, it "is not required to



        8
       The government asserts that this argument is waived for lack
of development. See United States v. Zannino, 895 F.2d 1, 17 (1st
Cir. 1990).
                                       - 47 -
address frontally every argument advanced by the parties, nor need

it dissect every factor made relevant by . . . § 3553 'one by one,

in some sort of rote incantation, when explicating its sentencing

decision.'"   United States v. Turbides-Leonardo, 468 F.3d 34, 40-

41 (1st Cir. 2006) (quoting United States v. Dixon, 449 F.3d 149,

205 (1st Cir. 2006)).   Nor is there a "requirement that a district

court afford each of the section 3553(a) factors equal prominence."

Dixon, 449 F.3d at 205.

                                  2.

          We turn, then, to Tanco's challenges to the substantive

reasonableness of his sentence.    He asserts that his sentence was

too harsh given his personal characteristics.     "But the fact that

the court chose to attach less significance to certain mitigating

circumstances than [he] thinks they deserved does not make his

sentence substantively unreasonable."      United States v. Mangual-

Rosado, 907 F.3d 107, 111 (1st Cir. 2018) (internal alternations

and quotations omitted).    "Rather, a sentence is substantively

reasonable so long as it rests on a plausible sentencing rationale

and exemplifies a defensible result."      Id. (internal alterations

and quotations omitted).    And that is the case here, given the

unique features of the case that the District Court highlighted.

Therefore, we reject Tanco's substantive reasonableness challenge

to his sentence.


                                  - 48 -
                                 C.

            That brings us to Cepeda's challenge to his sentence.

Because we have reversed his conviction on Count One, all that

remains is his challenge to his sentence on Count Three.     Cepeda

makes the same arguments that Tanco made regarding the procedural

and substantive reasonableness of his sentence.    We have already

considered these arguments and found them wanting in rejecting

Tanco's sentencing challenge.    Nevertheless, we vacate and remand

Cepeda's sentence on Count Three, in which he was convicted of

illegal possession of a machinegun in violation of 18 U.S.C.

§ 922(o).

            As we have noted, the District Court determined that

Cepeda's BOL under the guidelines was 20, based in part on a

finding that he was a prohibited person at the time that he

committed the offense in consequence of his Count One conviction.

See U.S.S.G. § 2K2.1(a)(4)(B).    With a two-level enhancement for

the use of three or more firearms, the District Court found that

his TOL was 22, and his guidelines range was therefore 41-to-51

months' imprisonment.

            But, as we reverse Cepeda's conviction on Count One for

violating § 922(g)(3), that conviction cannot support the District

Court's prohibited person finding.     Nor did the District Court

separately find by a preponderance of the evidence that Cepeda was


                                  - 49 -
such a person, assuming that the record would support such a

finding.

              Thus, the record does not contain findings that could

support the District Court's determination that Cepeda's BOL was

20 -- and thus that his TOL was 22 rather than 20, due to the two-

level multiple firearms enhancement.                  Accordingly, the record

lacks   the    findings    that    could     support    the   District   Court's

determination that his guidelines range for his conviction on Count

Three is for a sentence of 41-to-51 months' imprisonment rather

than, as Cepeda contends, for 33-to-41 months' imprisonment, as

would be the case if his TOL were only 20 rather than 22.

              The question, then, is whether we must vacate and remand

Cepeda's sentence.        It is possible the District Court might have

arrived at the same 120-month sentence even under the reduced

guidelines     range.     The     District    Court    clearly   intended   that

Cepeda's sentence reflect his ties to the Delgado murder, and it

stated both that it was "perform[ing] a variance upward to the

highest end of . . . the statute," and that it was going to "make

a variant because there's a murder," even if the TOL was only 20.

We also recognize that, on remand, the District Court potentially

could, under the less demanding "preponderance of the evidence"

standard, make an independent determination that Cepeda is an

unlawful user and therefore a prohibited person, and still arrive

at the same TOL of 22.          After all, we are aware of no authority
                                        - 50 -
-- and Cepeda supplies none -- that would indicate that, because

the corroboration rule precludes his admission about the nature

and duration of his drug use from supporting a jury finding that

he was a regular, long-term drug user beyond a reasonable doubt,

that admission -- considered in the context of the record as a

whole -- could not support a finding at sentencing to that effect

under the less onerous preponderance of the evidence standard.

          But, the Court relied solely on Cepeda's conviction on

Count One in deeming him a prohibited person and thus did not

independently make any such finding on that score.   Moreover, the

record as to whether he is such a person is too uncertain for us

to conclude that the District Court's reliance on the now-reversed

conviction to calculate the guidelines range was harmless.

          Nor can we say it is sufficiently clear that the District

Court would have imposed the same upward variance even if the

guidelines range were premised on the lower TOL that would apply

in the event the District Court did not find Cepeda to be a

prohibited person on remand.   Even under the more stringent plain

error standard, "[w]hen a defendant is sentenced under an incorrect

Guidelines range . . . the error . . . most often will[] be

sufficient to show a reasonable probability of a different outcome

absent the error."   Molina-Martinez v. United States, 136 S. Ct.

1338, 1345 (2016).


                                - 51 -
            Here,   the    District       Court   began    its    analysis     by

calculating the guidelines range. And, while it ultimately imposed

a sentence outside that range, the record does not indicate that

the guidelines played no role in its decision, or that the District

Court would have made the exact same upward variance regardless of

the sentencing range set forth in the guidelines.                For while the

District Court stated that it would impose "a variant" sentence in

light of the evidence showing Cepeda's relationship to Delgado's

murder, the District Court was not clear in stating that the extent

of that variance would necessarily be to the statutory maximum

sentence even if the defendant's TOL was lower than the District

Court had determined that it was.           Accordingly, our reading of the

record is that, as is ordinarily the case, the error here was not

harmless,   as    the   "judge   use[d]     the   sentencing     range   as   the

beginning point to explain [his] decision to deviate from it," and

the guidelines were "in a real sense the basis for the sentence."

Molina-Martinez, 136 S. Ct. at 1345 (emphasis omitted) (quoting

Peugh v. United States, 569 U.S. 530, 542 (2013)).

                                      IV.

            For   the   above    stated    reasons,   we   affirm   all   three

defendants' convictions on Count Three and Tanco's conviction on

Count Two. We reverse Cepeda's conviction on Count One. We affirm

Tanco's sentence and vacate and remand Cepeda's sentence.


                                       - 52 -
