                             PUBLISHED

                 UNITED STATES COURT OF APPEALS
                     FOR THE FOURTH CIRCUIT


                            No. 13-4806


UNITED STATES OF AMERICA,

               Plaintiff – Appellee,

          v.

ROBERT ALLEN HILL,

               Defendant – Appellant.



                            No. 13-4811


UNITED STATES OF AMERICA,

               Plaintiff – Appellee,

          v.

ERIC SCOTT BARKER,

               Defendant – Appellant.



                            No. 13-4820


UNITED STATES OF AMERICA,

               Plaintiff – Appellee,

          v.
MEGAN EILEEN DUNIGAN,

                Defendant – Appellant.



Appeals from the United States District Court for the Northern
District of West Virginia, at Clarksburg.      Irene M. Keeley,
District Judge.     (1:13-cr-00018-IMK-JSK-3; 1:13-cr-00018-IMK-
JSK-1; 1:13-cr-00018-IMK-JSK-2)


Argued:   September 19, 2014             Decided:   January 13, 2015


Before DIAZ and THACKER, Circuit Judges, and Paul W. GRIMM,
United States District Judge for the District of Maryland,
sitting by designation.


Vacated and remanded by published opinion. Judge Diaz wrote the
opinion, in which Judge Thacker and Judge Grimm joined.


ARGUED: Andrew Brooks Greenlee, BROWNSTONE, P.A., Winter Park,
Florida; Brian Joseph Kornbrath, OFFICE OF THE FEDERAL PUBLIC
DEFENDER, Clarksburg, West Virginia; David I. Schoen, DAVID I.
SCHOEN, ATTORNEY AT LAW, Montgomery, Alabama, for Appellants.
Shawn Angus Morgan, OFFICE OF THE UNITED STATES ATTORNEY,
Clarksburg, West Virginia, for Appellee.     ON BRIEF: Roger D.
Curry, CURRY, AMOS, AND ASSOCIATES, Fairmont, West Virginia, for
Appellant Megan Dunigan.     William J. Ihlenfeld, II, United
States Attorney, OFFICE OF THE UNITED STATES ATTORNEY, Wheeling,
West Virginia, for Appellee.




                                 2
DIAZ, Circuit Judge:

     We consider here the scope of Fourth Amendment protections

as applied to individuals on federal supervised release.                                   In

February    2013,     Eric    Barker     was     serving       a    term    of   supervised

release    in   connection        with   a       felony    drug      conviction.          His

conditions      of    supervised     release           required      him,     among      other

things, (1) to notify his probation officer if he moved and (2)

to permit probation officers to visit him at home at any time

and confiscate contraband in plain view.

     Law     enforcement       officials          suspected          Barker      of   moving

without notification, obtained a warrant for his arrest, and

executed it at his new home.              Inside, they found Barker and two

other     individuals      also    on    supervised            release.          After    the

officers    had      all   three   in    custody         and       had   completed       their

protective sweep, they conducted a walk-through of the apartment

to look for contraband and other evidence of supervised release

violations.       Officers then had a drug-detection dog sniff around

the apartment.        Only after the dog alerted did the officers seek

a search warrant.

     The defendants contend that the walk-through and dog sniff

violated    the      Fourth   Amendment.           Our     precedent        required       the

officers in this situation to have a search warrant rather than

merely      reasonable        suspicion           to      search         Barker’s        home.

Accordingly, we hold that the walk-through and dog sniff were

                                             3
unlawful searches.              We also reject the government’s contention

that     the       good-faith      exception           applies      with     respect    to     the

evidence seized as a result of the dog sniff.                                    Finally, we

vacate       the    judgments         and   remand       for      the   district       court    to

properly consider whether, pursuant to the “independent source”

doctrine,          the    officers     in     this      case      “‘would     have     sought    a

warrant’       even        if    they       had        not       conducted     the     unlawful

search[es].”             United States v. Bullard, 645 F.3d 237, 244 (4th

Cir. 2011) (quoting Murray v. United States, 487 U.S. 533, 543

(1988)).



                                                  I.

                                                  A.

        In    late       January      2013,    Officer           Vincent     Zummo,    Barker’s

probation officer, received a tip from a confidential informant

that Barker had moved without notifying him.                                  On February 8,

2013, a magistrate judge issued an arrest warrant for Barker for

violating the conditions of his supervised release.                              Deputy U.S.

Marshal Terry Moore assembled a ten-member team to execute the

warrant.           The team included deputy marshals, local drug task

force officers, and the Chief U.S. Probation Officer.                                  They met

Zummo    at    Barker’s         new    residence,            a   two-story     house     with    a

ground-floor apartment and an upstairs apartment.                                    An officer

knocked on the door, and a marshal announced the team’s identity

                                                  4
and      purpose.            The    landlady       answered     and   said       “Eric    lives

upstairs.”              Zummo      and    the     Chief    Probation        Officer      stayed

downstairs.            The rest of the team filed up the stairs.

         At the top, Moore opened the bathroom door.                         He saw Barker

inside, ordered him to lie down, and handcuffed and arrested

him. 1         Team members then fanned out to conduct a protective

sweep.         A deputy marshal went left, forced open a locked bedroom

door, and found Megan Dunigan hiding behind a bed.                                An officer

went     right,        entered      a    second    bedroom,     and   found      Robert     Hill

inside.          Dunigan and Hill were both handcuffed.                           Zummo went

upstairs and identified them as also on supervised release.                                  He

then         called    the    magistrate        judge     to   tell   him    that,       besides

Barker, the officers had found two others in violation of their

supervised release conditions.                    Dunigan and Hill were arrested.

         During the protective sweep, the officers saw needles in

the bathroom, a homemade tourniquet on Barker’s arm, pills on

the locked bedroom’s dresser, packaging for synthetic marijuana

on    the      kitchen       table,      and    drug    paraphernalia       on    the     second

bedroom’s dresser.

         After        Barker,      Dunigan,     and     Hill   were   arrested        and   the

protective sweep had ended, Zummo and other arrest team members

conducted        a     walk-through        of     the   apartment     looking      for    other

         1
       Moore searched Barker and found more than $1,000 on his
person.


                                                   5
evidence of supervised release violations.                             They looked “[o]n

top of cabinets, on top of the bed, [and] in the closet” of the

second bedroom.         J.A. 118.          Officers found scales, wax paper,

and black electrical tape in the living room.                          Zummo seized cell

phones    and    an    intravenous        drug     use        kit   containing       needles,

cotton    balls,      and   spoons     from       on    top    of   the   bathroom         sink.

After the walk-through, Zummo requested that a trained drug-

detection dog come to the apartment.

      About     fifteen     to    twenty    minutes           later,    the    dog   and     his

handler arrived.        The dog alerted positively in many places.                           In

the bathroom, the dog alerted “high,” meaning that he smelled

the odor of narcotics above his reach.                         That alert led officers

to an out-of-place ceiling tile, where they saw a plastic bag

tucked inside the ceiling.

      At that point, the officers stopped the search and secured

the apartment.          Task Force Agent Robert Root, an arrest team

member,    applied      for      and   obtained          a    warrant     to    search       the

apartment.         Root’s      accompanying            affidavit       detailed      his    law

enforcement experience; the circumstances of the arrest warrant

execution,      protective       sweep,    and         walk-through;      the    contraband

and paraphernalia discovered during those activities; and the

drug dog alerts.            The officers’ subsequent search pursuant to

the   warrant         turned      up    packaged             and    unpackaged        heroin,



                                              6
prescription pills, suspected LSD, synthetic marijuana, and drug

use paraphernalia.

                                          B.

      The defendants were charged with conspiracy to possess with

intent to distribute heroin, aiding and abetting possession with

intent     to   distribute      heroin,        and    aiding     and    abetting    the

maintenance of a drug-involved residence.                  They filed motions to

suppress    evidence        challenging    the       lawfulness        of   the   arrest

warrant    execution,       protective    sweep,       walk-through,        dog   sniff,

and the search warrant’s validity.                   They also sought to exclude

evidence found during the execution of the search warrant as

fruit of the poisonous tree.

      At the suppression hearing, the government conceded that

the   defendants      had    standing     to    press    their    Fourth      Amendment

challenges, either because they lived in the apartment (in the

case of Barker and Dunigan) or stayed there as an overnight

guest (in the case of Hill).             The magistrate judge took judicial

notice     of   the   defendants’        supervised       release       terms,     which

included Standard Condition of Supervision No. 10 requiring each

defendant to “permit a Probation Officer to visit him or her at

any time, at home or elsewhere, and [to] permit confiscation of

any contraband observed in plain view of the Probation Officer.”

J.A. 124.       The magistrate judge recommended denying the motions

to suppress.

                                           7
        The district court adopted the magistrate judge’s report

and recommendation.             For the walk-through and dog sniff, the

district court applied a reasonable suspicion standard and found

that both searches met it.                The court relied on United States v.

Knights,       534   U.S.    112     (2001),        which    upheld       as   reasonable        a

warrantless search of a probationer’s home when officers had

reasonable         suspicion    and       the       probationer         had    agreed      to    a

probation      condition       allowing       warrantless          home    searches.            The

court       reasoned   that,       like    in       Knights,       Barker’s         supervision

condition allowing his probation officer to visit him at home at

any   time     diminished      his    expectation           of    privacy      to    the   point

where officers needed only reasonable suspicion, not a warrant,

for the walk-through and dog sniff.                          The district court also

applied United States v. Karo, 468 U.S. 705 (1984), to conclude

that sufficient untainted evidence established probable cause to

support the search warrant, even if the walk-through and dog

sniff       were   illegal     and    their     results          were   excised       from      the

warrant application. 2

        The defendants entered conditional guilty pleas to aiding

and abetting possession with intent to distribute heroin and

preserved the right to appeal the denial of their suppression


        2
       The district court also found the arrest warrant execution
and protective sweep lawful, conclusions that the defendants
have not appealed.


                                                8
motions.     The district court sentenced Barker to 151 months in

prison, Dunigan to 18 months, and Hill to 27 months.                      The court

also imposed three years’ supervised release on each of them.

Special    Condition       of    Supervision       No.     6    will   require     the

defendants to submit to warrantless searches of their persons,

property, residences, or vehicles based on a probation officer’s

reasonable suspicion.



                                          II.

                                          A.

      When considering a motion to suppress, we review de novo

the   district      court’s     legal     conclusions.          United   States    v.

Williams, 740 F.3d 308, 311 (4th Cir. 2014).                     In its brief, the

government frames its arguments in terms of clear error, which

we use to evaluate the district court’s factual findings.                          Id.

But because the parties do not dispute the facts, de novo review

is proper.

                                          B.

      The defendants contend that once the protective sweep of

the apartment had ended, the officers needed a warrant to go any

further.         The     government       responds       that    the     defendants’

supervised       release        status,        including       their     supervision

conditions,    so      diminished    their      expectation      of    privacy    that



                                           9
officers needed only reasonable suspicion to conduct the walk-

through and dog sniff.           We agree with the defendants.

       This case is remarkably similar to one we decided thirty-

six years ago, United States v. Bradley, 571 F.2d 787 (4th Cir.

1978).    Bradley was on parole with a condition requiring that he

“permit    his   Parole        Officer       to    visit    his    home   or     place    of

employment.”        571    F.2d       at    788    (internal      quotation     marks    and

alterations      omitted).            No    parole    condition        required    him    to

consent to searches.             Bradley’s parole officer received a tip

that he was violating a parole condition that prohibited him

from having a firearm.                 Acting on the tip, Bradley’s parole

officer went to the boarding house where Bradley lived, searched

his room, and found a firearm.                Id.

       We held that “a parole officer must secure a warrant prior

to conducting a search of a parolee’s place of residence even

where, as a condition of parole, the parolee has consented to

periodic and unannounced visits by the parole officer.”                            Id. at

789.      In   reaching        this    conclusion,         we   recognized      that    “the

governmental interest in supervision is great and the parolee’s

privacy    interest       is    diminished.”          Id.         We   also    noted    “the

special relationship between the parolee and his parole officer”

and    “society’s     interest         in    having    the      parolee       closely    and

properly supervised.”            Id. at 790.         However, we found that these



                                              10
considerations did not excuse the parole officer from complying

with the Fourth Amendment’s warrant requirement.                         Id.

       As in Bradley, the defendants here agreed to home visits by

a    probation     officer      but    not        warrantless         searches.      Unlike

Bradley, however, the defendants also agreed that a probation

officer could visit them “at any time” and confiscate contraband

in   plain   view.       This,        however,         is   a   distinction       without    a

difference,      as    the     fact    remains         that     the   defendants,     as    in

Bradley,     did   not       consent    to       warrantless      home    searches     as    a

condition of supervision.

       Thus, Bradley controls the outcome here unless intervening

case law from our court sitting en banc or the Supreme Court has

explicitly or implicitly overruled it.                           Bullard, 645 F.3d at

246.    Since Bradley, the Supreme Court has decided three cases

dealing with the privacy interests of individuals on probation

or parole.     None calls into question Bradley’s core holding.

       In Griffin v. Wisconsin, 483 U.S. 868, 870-71 (1987), the

Court considered whether a probation condition applicable to all

Wisconsin probationers via state regulations comported with the

Fourth Amendment when it allowed a probation officer to search a

probationer’s         home     without       a     warrant       if    the   officer       had

reasonable grounds to believe that contraband was present.                                 The

Court upheld the condition under the “special needs” exception

to   the   warrant     requirement.              483    U.S.     at   873-80.      Notably,

                                             11
however, the Court confined its decision to the facts before it

(a    warrantless       search       pursuant      to     an     express    regulation

authorizing the same) and declined to approve all searches of a

probationer’s        home    predicated    solely       on     reasonable   suspicion.

Id. at 872, 880.            In short, the Court did not reach the question

we    decided   in    Bradley,       namely,    whether      a   parole    officer      may

search a parolee’s home without a warrant when no regulation or

individual parole condition allows it.

       In United States v. Knights, 534 U.S. 112, 114 (2001), the

defendant was on probation subject to a condition that he submit

to searches of his person, property, residence, or vehicle “with

or without a search warrant, warrant of arrest or reasonable

cause by any probation officer or law enforcement officer.”                             The

Court held that a probation officer with reasonable suspicion

could search a probationer’s residence without a warrant when

the probationer had agreed to a warrantless search condition.

534    U.S.    at    118.      Importantly,      the     Court     found    the   search

reasonable under the totality of the circumstances, “with the

probation search condition being a salient circumstance.”                         Id.

       To     determine       the     search’s     reasonableness,          the    Court

balanced the privacy intrusion against the government’s need to

conduct       the    search     to     promote     its       legitimate     interests.

Relevant to both was Knights’s “status as a probationer subject

to a search condition.”              Id. at 119.        On the intrusion side, the

                                           12
Court       concluded          that        “[t]he         probation         condition . . .

significantly diminished Knights’[s] reasonable expectation of

privacy.”          Id.    at       119-20.      On        the    need     side,     the    Court

identified the government’s interest in monitoring probationers

closely     because       of   their       greater       likelihood        of    committing      a

crime than the general population.                        Id. at 121.           The Court held

that “the balance of these considerations requires no more than

reasonable suspicion to conduct a search of this probationer’s

house.”     Id. (emphasis added).

      In    our    view,       however,       the    specific         probation         condition

authorizing       warrantless         searches       was       critical     to    the     Court’s

holding.          Indeed,      at    the     close       of     the   opinion,      the     Court

referenced        the     probation          condition          in    holding      “that       the

warrantless search of Knights, supported by reasonable suspicion

and   authorized         by    a    condition       of     probation,       was     reasonable

within the meaning of the Fourth Amendment.”                              Id. at 122.          The

Court      also    underscored         that     the           “probation        order    clearly

expressed     the       search      condition       and       Knights    was     unambiguously

informed of it.”               Id. at 119.           In contrast, the supervision

condition to which the defendants agreed in this case required

them to submit to a probation officer’s visit and allowed an

officer     to     confiscate         contraband          in     plain     view.         But    no

condition authorized warrantless searches.



                                               13
       The last case in this trilogy, Samson v. California, 547

U.S.   843    (2006),       also      did    not      vitiate       Bradley       because,         like

Knights,      it     emphasized        the      parolees’           notice       of    an       express

warrantless         search       condition.                 Samson       involved          a     Fourth

Amendment         challenge      to    a     California        statute       requiring           every

prisoner      eligible       for      release         on    state       parole    to    “agree       in

writing      to    be    subject      to”    warrantless            searches      by    parole      or

peace officers “at any time of the day or night, . . . with or

without      cause.”        547       U.S.      at    846    (quoting        Cal.      Penal      Code

§ 3067(a) (West 2000)).                    The Court held that “a condition of

release      can    so     diminish        or    eliminate          a    released       prisoner’s

reasonable expectation of privacy that a suspicionless search by

a   law      enforcement          officer        would        not        offend        the      Fourth

Amendment.”          Id.    at     847.         But    as    was     the   case       in       Knights,

central to the Court’s holding was the undisputed fact that the

California        parole     condition          had    been    “‘clearly          expressed’         to

[the] petitioner” and he was “‘unambiguously’ aware of it.”                                        Id.

at 852 (quoting Knights, 534 U.S. at 119).

       We are satisfied that Griffin, Knights, and Samson did not

overrule our decision in Bradley. 3                         Accordingly, Bradley remains


       3
       The Fifth and Eleventh Circuits have taken a broader view
of these cases.   See United States v. Keith, 375 F.3d 346, 350
(5th Cir. 2004) (declining to read Knights or Griffin “as
requiring either a written condition of probation or an explicit
regulation permitting the search of a probationer’s home on
(Continued)
                                                 14
good        law   in    our     circuit,   and      thus   law   enforcement     officers

generally may not search the home of an individual on supervised

release who is not subject to a warrantless search condition

unless they have a warrant supported by probable cause. 4                            Here,

the officers did not have a warrant when they conducted the

walk-through and dog sniff, and those searches were therefore

unlawful.

                                              III.

                                               A.

        “The        exclusionary       rule      generally       renders    inadmissible

evidence recovered during an unlawful search.”                        United States v.

Mowatt, 513 F.3d 395, 403 (4th Cir. 2008), abrogated in part by

Kentucky v. King, 131 S. Ct. 1849 (2011).                           In this case, the

government makes two arguments against exclusion.                          With respect

to   the      dog      sniff,    the   government      contends     that   the   officers

relied in good faith on then-binding appellate precedent holding

that a dog sniff was not a search.                         Separately, the government

urges        that      the    “independent       source”      doctrine     rescues   from

exclusion the evidence recovered during the walk-through and dog



reasonable suspicion”);   United States v. Yuknavich, 419 F.3d
1302, 1310-11 (11th Cir. 2005) (same).        Of course, those
circuits were writing on a clean state, while we are constrained
by Bradley.
        4
       The government in this case does not suggest that any
other exception to the warrant requirement applies.


                                               15
sniff    because       the    officers      later    conducted      a    search    of    the

apartment with a warrant.

       As   we    explain,      we    disagree      with    the    government’s         first

argument,        and   remand        the   case     to   the      district      court     for

consideration of the second.

                                             B.

       We first consider whether the officers relied in good faith

on    binding     appellate      precedent        when     they    conducted      the    dog

sniff.      The government concedes that the dog sniff would have

been an illegal search after the Supreme Court’s recent decision

in Florida v. Jardines, 133 S. Ct. 1409 (2013).                              But, says the

government, the officers in this case relied in good faith on

pre-Jardines precedent holding that a dog-sniff was not a search

and    therefore       no    warrant       was    required.        As    a    result,    the

government contends, the good-faith exception saves the fruits

of the now-illegal search from exclusion.                      We cannot agree.

       “[S]earches conducted in objectively reasonable reliance on

binding appellate precedent are not subject to the exclusionary

rule.”      Davis v. United States, 131 S. Ct. 2419, 2423-24 (2011).

After the dog sniff in this case, the Supreme Court held in

Jardines that a dog sniff of a home’s curtilage “is a ‘search’

within the meaning of the Fourth Amendment.”                            Jardines, 133 S.

Ct. at 1417-18.             Whether the Davis good-faith exception applies



                                             16
depends      on    the    “binding          appellate      precedent”      that     pre-dated

Jardines.

       The government points us to United States v. Jeffus, 22

F.3d    554       (4th        Cir.     1994),      as     the     relevant       pre-Jardines

precedent.        Jeffus held that a dog sniff of a vehicle’s exterior

in a public place during a lawful traffic stop was not a search.

22 F.3d at 557.               To reach that conclusion, we relied on United

States v. Place, 462 U.S. 696, 707 (1983), where the Supreme

Court found that a dog sniff of luggage in a public place was

not a search.

       According to the government, the officers reasonably relied

on our Jeffus holding when they took a drug dog into the home of

an   individual          on    supervised         release,      without      a    warrant     or

consent.      Jeffus, however, involved a dog sniff of the outside

of a vehicle, not the inside of a home.                           We have not found, and

the government does not cite to, any pre-Jardines case decided

by   the     Supreme       Court       or    this       circuit    that    approved      of    a

warrantless dog sniff inside a home.

       The    defendants         draw       our   attention       to    United     States     v.

Whitehead,        849    F.2d    849     (4th     Cir.     1988),      abrogated    on   other

grounds by Gozlon-Peretz v. United States, 498 U.S. 395 (1991),

as the appropriate pre-Jardines precedent.                          Whitehead involved a

warrantless         dog        sniff        of    a     passenger       train’s      sleeping

compartment.             We     held     that      the    sniff     required       reasonable

                                                  17
suspicion, not a warrant and probable cause, because occupants

have        lower       expectations            of        privacy        in     their     sleeping

compartments than in their homes or hotel rooms.                                     849 F.2d at

853, 856-57.

       Never did we say in Whitehead that the dog sniff was not a

search.           Instead,        we    noted    that       “when        authorities      bring    a

narcotics         detection       dog    into        an    area     in    which     the   occupant

enjoys       an     expectation         of    privacy,        the        [F]ourth    [A]mendment

extends to protect the owner against ‘unreasonable’ intrusions.”

Id.    at    858.          We    made    clear       that     “Place          obviously   did    not

sanction the indiscriminate, blanket use of trained dogs in all

contexts.”           Id. at 857.             Neither did Jeffus.                   Therefore, we

conclude that the officers could not have reasonably relied on

any binding appellate precedent when conducting the dog sniff in

this   case       and      that    the    Davis       good-faith          exception       does   not

apply.

                                                 C.

       We turn now to the government’s claim that the independent

source doctrine saves from exclusion the fruits of the searches

in this case.            This doctrine applies when a “search pursuant to

[a] warrant was in fact a genuinely independent source of the

information          and    tangible         evidence”        that        would    otherwise      be

subject to exclusion because they were found during an earlier

unlawful search.                Murray, 487 U.S. at 542.                   To find the search

                                                 18
with a warrant “genuinely independent,” the unlawful search must

not   have   affected    (1)   the    officer’s    “decision     to   seek   the

warrant” or (2) the magistrate judge’s “decision to issue [it].”

Id.

      The district court found that the magistrate judge would

have issued the warrant absent the evidence from the illegal

searches, but did not consider Murray’s first prong that speaks

to the officer’s decision to seek it.             The court cited Karo, 468

U.S. 705, and our decision in United States v. Allen, 631 F.3d

164 (4th Cir. 2011), to support its single-step analysis.

      We find that the district court erred in not applying both

Murray prongs.        This case differs from Karo because the law

enforcement officers there acted pursuant to a warrant at all

times, whereas the officers in this case did not.                In Karo, the

officers first sought a warrant “authorizing the installation

and monitoring of a beeper” in a can of ether before installing

or monitoring the beeper.          468 U.S. at 708.      Officers had a tip

that the ether “was to be used to extract cocaine from clothing

that had been imported into the United States.”                   Id.      Using

their results from visual and beeper surveillance, officers then

applied for a search warrant for a residence where the can of

ether was stored.       Id. at 710.         The district court later found

the beeper warrant invalid.          Id.    But because the government did

not   appeal   that     finding,     the    reviewing   courts   treated     the

                                       19
installation    and   monitoring    of     the    beeper    as   if    conducted

without a warrant.       Id. at 711; United States v. Karo, 710 F.2d

1433, 1436 (10th Cir. 1983), reversed by Karo, 468 U.S. 705.

       This situation left the government arguing that no warrant

was needed for the beeper installation and monitoring despite

the fact that the officers had indeed sought a warrant for those

activities.     Karo, 468 U.S. at 711.            The Supreme Court agreed

that a warrant was unnecessary to install a beeper, but held

that a warrant was necessary to monitor the beeper inside a

residence.     Id. at 713-14.     However, the Court found suppression

unnecessary    because    “sufficient      untainted       evidence”        in   the

search warrant affidavit established probable cause.                        Id. at

719, 721.

       Here, the officers conducted the walk-through and dog sniff

before seeking a search warrant.           Although the officers had an

arrest warrant, the government has not argued--nor could it--

that   the   walk-through   and    dog    sniff   fell     within     the    arrest

warrant’s scope.      Murray thus presents a better fit than Karo on

the facts before us.        The agents in Murray first forced entry

into a warehouse without a warrant, and then sought a search

warrant for the warehouse.         487 U.S. at 535-36.              Unlike Karo,

the sequence of events in Murray raised a question as to whether

“the agents’ decision to seek the warrant was prompted by what



                                     20
they had seen during the [illegal] entry.”                 Id. at 542.          The

record here raises similar questions.

       We recognize that the district court relied on one of our

post-Murray      cases,   Allen,    that   employed     Karo’s     single-prong

test.       However,   like   the   Supreme   Court   in   Karo,    we    had    no

occasion in Allen to consider the officers’ decision to seek a

warrant.      The officers in Allen, responding to a call about a

firefight, saw “twenty spent shell casings,” and “several blood

trails, one of which led directly into” a store.                   631 F.3d at

167.       Before seeking a search warrant, an officer followed the

blood trail into the store, saw that it led to a filing cabinet,

opened a cabinet drawer, and found a revolver inside.                    Id.    On

these facts, there was no doubt (and Allen did not contest) that

officers would have sought a search warrant for the store into

which a blood trail led, even without the officer’s unlawful

search of the filing cabinet. 5

       But where the facts call into question whether an illegal

search affected an officer’s decision to seek a warrant, the

district      court    should   consider      both    Murray     prongs        when

evaluating      whether   the   independent    source      doctrine      applies.

       5
       Likewise, in two other published, post-Murray cases, we
had no reason to question whether earlier illegal activity
prompted the officer’s decision to seek a warrant because the
defendants did not contest it. See United States v. Moses, 540
F.3d 263, 268 (4th Cir. 2008); United States v. Gillenwaters,
890 F.2d 679, 681-82 (4th Cir. 1989).


                                      21
See, e.g., Bullard, 645 F.3d at 244-45; United States v. Walton,

56 F.3d 551, 554 (4th Cir. 1995).

                                          D.

      The district court found that the unlawful walk-through and

dog   sniff   did    not   affect   the    magistrate     judge’s   decision   to

issue the warrant, and the defendants have not challenged this

finding.      The defendants, however, contend that Officer Root’s

suppression hearing testimony shows that the unlawful searches

influenced his decision to seek a warrant.                 In particular, the

defendants    rely    on   two   exchanges     in   the   record.    The   first

occurred during Root’s direct examination:

      Q: Do you know at what point you decided to seek a
      search warrant?

      A: With all the paraphernalia that was seen inside the
      residence, the empty packaging of the synthetic
      marijuana, and the alert by the dog in multiple areas
      of the residence.   At that point we decided to get a
      search warrant.

J.A. 92 (emphasis added).            The second happened during cross-

examination:

      Q: Who made the decision to apply to the Court for a
      search warrant?

      A: I did.

      Q: And at what point did you make that decision?
      Before the drug dog was there and it sniffed, or after
      the drug dog was there and it sniffed?

      A: It was after.

J.A. 96.

                                          22
      In addition to the two passages above, the government asked

Root, “Did you plan that day [of the arrest] to obtain a search

warrant?”        He   responded,     “No,   I   didn’t.”        J.A.   86.      The

government and Root also had the following exchange:

      Q: How long were you there [at the apartment] before
      you decided to seek a search warrant?

      A: We had the canine come through. We had been there
      probably 15 minutes, at least, with all the phone
      calls that were made, and arrangements being made to
      transport the defendants.

J.A. 91-92.      Later on, the district court questioned Root about

the sequence of events.         After recapping the walk-through, the

court asked, “What did you next do?”             Root replied, “After that,

when we called for the canine, the canine did a search of the

residence.       After the search of the residence, I called U.S.

Attorney     Shawn    Morgan   and    decided     to    apply    for    a    search

warrant.”    J.A. 118.

      The    government    interprets       Root’s     testimony       as    merely

stating a fact, i.e., that he did not seek the warrant until

after the dog sniff, not as describing what Root would have done

had the illegal searches never happened.               We also note that Root

had seen considerable drug paraphernalia in plain view 6 before

the   officers    conducted    the    walk-through      and   dog   sniff,     thus



      6
       Not least of which was a homemade tourniquet dangling from
Barker’s arm.


                                       23
supporting the view that Root would have sought a warrant even

if the officers had not conducted the unlawful searches.

       We    decline       to   resolve      this   factual         question    on    appeal.

Rather, we think it best for the district court to consider the

issue in the first instance.                   See Murray, 487 U.S. at 543-44

(remanding         for    the   district     court       to    make    a    finding   on   the

officer’s         decision      prong   of   the    analysis        because     “it   is   the

function of the District Court rather than the Court of Appeals

to determine the facts”); United States v. Campbell, 945 F.2d

713, 716 (4th Cir. 1991) (remanding for the district court to

make     factual         findings       related     to        the     independent     source

doctrine’s applicability).



                                              IV.

       For    the    foregoing      reasons,        we    vacate      the    judgments     and

remand       to     the     district      court      to       determine        whether     the

information gained from the illegal walk-through and dog sniff

affected Officer Root’s decision to seek a warrant.



                                                                    VACATED AND REMANDED




                                              24
