                 FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 06-50595
                Plaintiff-Appellee,
               v.                            D.C. No.
                                          CR-03-01249-DSF
RAMON SANCHEZ FERNANDEZ,
                                             OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
          for the Central District of California
        Dale S. Fischer, District Judge, Presiding

                  Argued and Submitted
          February 5, 2008—Pasadena, California

                    Filed May 27, 2008

 Before: Alfred T. Goodwin, Diarmuid F. O’Scannlain, and
            William A. Fletcher, Circuit Judges.

              Opinion by Judge O’Scannlain




                           6015
                UNITED STATES v. FERNANDEZ            6017


                       COUNSEL

G. David Haigh, Santa Ana, California, argued the cause for
the defendant-appellant and filed a brief.

Christopher Brunwin, Assistant United States Attorney, Los
Angeles, California, argued the cause for the plaintiff-
6018              UNITED STATES v. FERNANDEZ
appellee and filed a brief; George S. Cardona, United States
Attorney, and Thomas P. O’Brien, Assistant United States
Attorney, Chief, Criminal Division, were on the brief.


                          OPINION

O’SCANNLAIN, Circuit Judge:

   We must decide whether evidence obtained from an autho-
rized wiretap investigation must be suppressed where the gov-
ernment continued to intercept a named target’s conversations
despite his adoption of a new alias.

                                I

                               A

  At the heart of this case are six wiretap orders obtained by
Drug Enforcement Agency investigators between May and
October 2003 as part of an investigation of a drug trafficking
conspiracy. At the outset of the investigation, the officers
believed that the conspiracy was headed by an individual
named Enrique Mendoza, and thus the first four wiretap appli-
cations submitted to the district court by the government
named Mendoza, among others, as a target.

   While intercepting a conversation on August 8, 2003, the
investigators for the first time learned that “Enrique Mendo-
za” was merely an alias used by their target suspect; they con-
cluded that he adopted a new alias “Jorge Acosta,” based on
their recognition of his voice. In their subsequent status
reports and wiretap applications to the district court, the
investigators gave detailed reports of intercepted calls involv-
ing “Acosta,” but they did not inform the district court of their
belief that “Mendoza” and “Acosta” were the same person.
Rather, the government’s subsequent wiretap applications
                  UNITED STATES v. FERNANDEZ                6019
now named as targets both “Jorge Acosta” and “Enrique Men-
doza,” among others.

   Soon thereafter, investigators intercepted conversations
between “Acosta” and Ramon Sanchez Fernandez arranging
for the transportation and sale of narcotics. They concluded
that Fernandez was a multi-kilogram narcotics broker who
negotiated and facilitated sales of narcotics for “Acosta.”
Accordingly, on December 12, 2003, investigators obtained a
warrant to search Fernandez’s residence. During the search,
they seized a cache of firearms that included a .22 Marlin
rifle, a .357 Magnum revolver, an Olympic Arms semi-
automatic rifle, a ballistic vest, and a military protective flak
vest.

                               B

   On March 16, 2004, the government indicted Fernandez
and eleven others for various offenses stemming from the
drug trafficking conspiracy. Fernandez was charged with con-
spiracy to distribute cocaine, in violation of 21 U.S.C. §§ 846,
841(a)(1), (b)(1)(A), and with aiding and abetting the distribu-
tion of cocaine, in violation of 18 U.S.C. § 2. The government
also sought criminal forfeiture of the proceeds of illegal drug
trafficking in his possession under 21 U.S.C. § 853.

   Fernandez moved to suppress evidence seized as a result of
the wiretap orders, arguing, in relevant part, that the govern-
ment took insufficient steps to minimize unauthorized surveil-
lance by continuing to intercept its target’s conversations after
he had adopted a new alias. The district court denied Fernan-
dez’s motion, finding that the investigators immediately and
in good faith recognized that “Acosta” and “Mendoza” were
the same person, and that the officers did not intend to
deceive the district court by failing to report such conclusion.
The district court therefore held that the wiretap orders
directly authorized investigators to intercept “Acosta” ’s tele-
phone conversations.
6020                 UNITED STATES v. FERNANDEZ
   Fernandez pled guilty to the charges, expressly reserving
the right to appeal the district court’s denial of his suppression
motion as well as any sentencing claims. The district court
sentenced Fernandez to 120 months in prison and five years
supervised release. In determining the applicable sentence, the
district court denied Fernandez’s motion for safety valve
relief from the mandatory minimum sentence, required by 18
U.S.C. § 3553(f), on the ground that the arms seized from his
residence were used in connection with the underlying drug
conspiracy.

   Fernandez timely appealed both his conviction and his sen-
tence.

                                    II

   [1] Fernandez first argues that the officers inadequately
minimized unauthorized interceptions by continuing to inter-
cept “Acosta” ’s conversations without express authorization.1
Wiretapping or electronic surveillance must “be conducted in
such a way as to minimize the interception of communica-
tions not otherwise subject to” authorized surveillance. 18
U.S.C. § 2518(5). “[Section 2518] ‘does not forbid the inter-
ception of all nonrelevant conversations, but rather instructs
the agents to conduct the surveillance in such a manner as to
‘minimize’ the interception of such conversations.’ ” United
States v. Bennett, 219 F.3d 1117, 1123 (9th Cir. 2000) (quot-
ing Scott v. United States, 436 U.S. 128, 140 (1978)); see also
United States v. McGuire, 307 F.3d 1192, 1199 (9th Cir.
2002) (“Minimization requires that the government adopt rea-
sonable measures to reduce to a practical minimum the inter-
ception of conversations unrelated to the criminal activity
under investigation while permitting the government to pur-
  1
   In a concurrently filed memorandum disposition, we address Fernan-
dez’s other arguments concerning the district court’s denial of his suppres-
sion motion. See United States v. Fernandez, No. 06-50595 (filed May 27,
2008).
                  UNITED STATES v. FERNANDEZ                6021
sue legitimate investigation.”). In considering whether ade-
quate minimization steps were taken, we must focus on “the
particular circumstances of the case.” McGuire, 307 F.3d at
1199-1200.

   [2] Here, the district court found that investigators immedi-
ately recognized that “Acosta” and “Mendoza” were the same
person. Accordingly, they necessarily had reasonable grounds
to conclude that conversations involving “Acosta” would be
tied to the “criminal activity under investigation,” id. at 1199,
and hence would fall within the ambit of the wiretap order,
which they previously obtained with regard to “Mendoza.”
Such conclusion is particularly warranted because the investi-
gators targeted a drug conspiracy. The Supreme Court has
held that “when the investigation is focusing on what is
thought to be a widespread conspiracy more extensive surveil-
lance may be justified in an attempt to determine the precise
scope of the enterprise.” Scott, 436 U.S. at 140. Thus, investi-
gators may account for the fact that “unlawful conspiracies do
not always lay bare their plans in explicit words” and that the
players in the conspiracy may use “secret code” in communi-
cating, McGuire, 307 F.3d at 1201, here by adopting false
names.

   Moreover, were we to hold that investigators must termi-
nate a wiretap surveillance whenever a target adopts a new
alias, such rule would frustrate government investigations
well beyond the limited scope of the minimization require-
ment. Participants of a drug conspiracy easily could rotate
between new aliases, which would have the perverse effect of
forcing officers to halt their investigation and trudge through
the time-consuming task of filing a new wiretap application.
Yet where investigators have a good faith belief that a target
merely has adopted a new alias, as here, requiring them to
engage in such procedures would impede the interest in “per-
mitting the government to pursue legitimate investigation[s],”
and would undermine the “ad hoc nature of any determination
of reasonableness.” Id. at 1199. Indeed, such rule would have
6022                 UNITED STATES v. FERNANDEZ
the absurd result of permitting officers to wiretap previously
unknown conspirators discovered in the course of its surveil-
lance, see United States v. Kahn, 415 U.S. 143, 157 (1974),
but prohibiting the continued interception of authorized tar-
gets who simply have adopted a new name.

   Our analysis is not altered by the existence vel non of an
individual actually named Enrique Mendoza, whom federal
officers at one point mistakenly believed was the leader of the
target drug conspiracy. Even after investigators discovered
that their target was a distinct individual who had adopted the
alias “Jorge Acosta,” their prior interceptions of his conversa-
tions provided ample evidence that “Acosta” was involved in
the target conspiracy. The wiretap order, which explicitly
authorized the targeting of “others unknown,” therefore per-
mitted the continued interception of “Acosta” ’s conversa-
tions. See Kahn, 415 U.S. at 157.2

   [3] Accordingly, we must conclude that, where the govern-
ment reasonably and in good faith concludes that the target of
its wiretap surveillance has adopted a new alias, it may con-
tinue to intercept such target’s conversations without violating
the § 2518(5) minimization requirement. The district court
therefore did not err in rejecting Fernandez’s contention that
the government violated such requirement by continuing to
intercept “Acosta” ’s conversations without express authoriza-
tion.

                                    III

   [4] Fernandez next argues that the district court clearly
  2
    Fernandez’s reliance on United States v. Capra, 501 F.2d 267 (2d Cir.
1974), is unavailing. There, the Second Circuit held that investigators vio-
lated the minimization requirement where they knowingly intercepted
calls involving an individual not named in the district court’s wiretap
order. Id. at 277. This case is distinguishable, however, because the tar-
geted individual remained the same throughout the surveillance.
                  UNITED STATES v. FERNANDEZ                6023
erred in finding that the arms seized from his residence were
used in connection with the underlying drug conspiracy, and
that the district court therefore erroneously denied his motion
for safety valve relief. Under 18 U.S.C. § 3553(f), a defendant
is entitled to relief from a mandatory minimum sentence if
five criteria are satisfied. Under the only criterion relevant in
this appeal, safety valve relief is available where “the defen-
dant did not . . . possess a firearm or other dangerous weapon
(or induce another participant to do so) in connection with the
offense.” § 3553(f)(2). “[T]he burden is on the defendant to
prove that it was ‘clearly improbable’ that he possessed a
firearm in connection with the offense.” United States v. Fer-
ryman, 444 F.3d 1183, 1186 (9th Cir. 2006). “[T]he circum-
stances in which the firearms were found, coupled with the
implausibility of the defendants’ explanations” may serve as
grounds for concluding that firearms were possessed in con-
nection with the offense of conviction. Id. “Offense” means
“the offense of conviction and all relevant conduct.” United
States v. Miller, 151 F.3d 957, 960 (9th Cir. 1998) (noting that
“[a]ny infraction is an offense, whether one is caught or not”).

   Fernandez argues that “any weapon possession was totally
unrelated” to the underlying conspiracy, because the alleged
drug transactions did not occur in his home, where the weap-
ons were found, and because he did not “ha[ve] physical pos-
session of them” during such transactions. Rather, he
contends that he possessed the weapons “simply to protect
[his] residence and family.”

   The district court disagreed with Fernandez’s characteriza-
tion of his offense, finding that Fernandez was involved in a
broad-based drug conspiracy for which “there was no particu-
lar location.” Thus, the district court concluded that, even if
Fernandez did not possess the weapons at the precise time and
place of his alleged drug transactions, Fernandez failed to
establish that, by storing the weapons in his home, he did not
possess them in the “conduct of the offense.” Finally, the dis-
trict court found implausible Fernandez’s explanation that he
6024              UNITED STATES v. FERNANDEZ
possessed the cache of arms merely to protect his family, but
it found that, in any event, Fernandez’s concern for his fami-
ly’s protection itself stemmed from the dangers created by his
involvement in a drug conspiracy. The district court therefore
held that Fernandez failed to carry his burden of establishing
that the weapons seized from his residence were not pos-
sessed in connection with the underlying drug conspiracy.

   [5] Here, the guns found in Fernandez’s residence were far
from the kind or quantity associated with family protection;
they included, as noted, not just a revolver, but two rifles and
two protective vests. While Fernandez may simply have
sought to overwhelm any would-be burglar in steadfast devo-
tion to his kindred’s welfare, we are satisfied the district court
did not clearly err in deeming such explanation implausible.
See Ferryman, 444 F.3d at 1186-87 (rejecting the defendant’s
explanation that eleven firearms found in his residence, six of
which were loaded, were for his family’s protection); see also
United States v. Smith, 175 F.3d 1147, 1148-49 (9th Cir.
1999) (rejecting the defendant’s explanation that a gun found
in his backpack was not connected to his marijuana garden
but instead was used to shoot snakes, where the “nature of the
gun was more in the form of a potential weapon than it was
. . . a sporting type of gun”) (internal quotation marks omit-
ted).

   [6] Moreover, regardless of Fernandez’s contention that the
weapons were not on his person during actual drug transac-
tions, we also are satisfied that the district court did not
clearly err in concluding that the storage of a large cache of
weaponry for protection from the dangers attendant to partici-
pation in a drug conspiracy is “relevant conduct” within the
purview of § 3553(f)(2). Miller, 151 F.3d at 960; see United
States v. Carrasco, 257 F.3d 1045, 1048 (9th Cir. 2001)
(“Firearms are known tools of the trade of narcotics dealing
because of the danger inherent in that line of work.”) (internal
quotation marks omitted).
                 UNITED STATES v. FERNANDEZ             6025
  [7] Accordingly, we must conclude that the district court
did not clearly err in denying Fernandez’s motion for safety
valve relief.

                             IV

   For the foregoing reasons, Fernandez’s conviction and sen-
tence are

  AFFIRMED.
