FILED
                                                        United States Court of Appeals
                                                                Tenth Circuit
                                PUBLISH
                                                              October 9, 2019
                UNITED STATES COURT OF APPEALS
                                                           Elisabeth A. Shumaker
                      FOR THE TENTH CIRCUIT

                    _________________________________

UNITED STATES OF AMERICA,

       Plaintiff - Appellee,

v.                                                No. 18-1062

FERNANDO DURAN,

       Defendant - Appellant.
                   _________________________________

              Appeal from the United States District Court
                      for the District of Colorado
                   (D.C. No. 1:17-CR-00135-RBJ-7)
                   _________________________________

Adam Mueller, Haddon, Morgan, and Foreman, P.C., Denver, Colorado, for
the Defendant - Appellant.

James C. Murphy, Assistant United States Attorney (Jason R. Dunn, United
States Attorney, with him on the brief) Office of the United States
Attorney, District of Colorado, for Plaintiff - Appellee.
                     _________________________________

Before BACHARACH, BALDOCK, and EBEL, Circuit Judges.
               _________________________________

BACHARACH, Circuit Judge.
               _________________________________
     After a jury trial, Mr. Fernando Duran was convicted on drug

charges. He appeals, arguing that
          the evidence was insufficient to convict on three of the counts
           and

          the district court abused its discretion in admitting testimony
           regarding prior drug transactions and interpretations of
           recorded calls.

We reject these arguments.

1.   An investigation into Mr. Jerrell Birch leads to the convictions of
     Mr. Duran.

     The case against Mr. Duran stemmed from an investigation involving

Mr. Jerrell Birch. The investigation included three controlled buys of crack

cocaine from Mr. Birch and wiretaps on two of his telephones. The

telephone calls aroused suspicion that Mr. Birch was buying cocaine from

Mr. Duran, and these suspicions led to the prosecution of Mr. Duran. At

trial, the government presented

          recorded telephone calls between Mr. Birch and Mr. Duran and

          testimony from law-enforcement officers describing the
           investigation and interpreting the conversations.

The jury found Mr. Duran guilty on four counts:

          Count 22: distributing and possessing cocaine with the intent to
           distribute on March 8, 2017 (see 21 U.S.C. § 841(a)(1) and
           (b)(1)(C)),

          Count 34: conspiring to distribute and possess cocaine and
           crack cocaine with the intent to distribute between February 1,
           2017, and March 31, 2017 (see 21 U.S.C. §§ 841(a) and 846),
           and

          Counts 35 and 36: using a telephone to facilitate the
           manufacture, distribution, and possession with intent to

                                     2
            distribute crack cocaine on March 8 and 11, 2017 (see 21
            U.S.C. § 843(b)). 1

2.    The evidence was sufficient to convict on Counts 22, 35, and 36.

      Mr. Duran challenges the sufficiency of the evidence supporting

Counts 22, 35, and 36. We reject these challenges.

      A.    Standard of Review

      We engage in de novo review, viewing the evidence in the light most

favorable to the government. United States v. Mirabal, 

,

1038 (10th Cir. 2017). Viewing “the evidence in this light, we will reverse

only if the trier of fact could not rationally have found guilt beyond a

reasonable doubt.” 

22: Distributing and Possessing Cocaine on March 8,
            2017

      On Count 22, the government presented evidence that included both

recorded calls and surveillance.

      1.    On March 8, after expressing happiness from Unc’s visit,
            Mr. Duran directs Mr. Birch to “raindrop it,” with the
            expectation of seeing “gooey, gooey.”

      Two of the calls took place on March 8, 2017. In these calls, Mr.

Duran acknowledged the presence of someone named “Unc,” telling Mr.




1
      Mr. Duran was acquitted on Count 24: distributing and possessing
cocaine with intent to distribute 28 grams or more of a substance
containing cocaine base (crack cocaine) on March 11, 2017.
                                      3
Birch to “raindrop it.” And Mr. Birch noted his anticipation of “gooey,

gooey.”

      The first conversation took place early in the afternoon. In this call,

Mr. Duran expressed happiness about a visit from Unc and told Mr. Birch

to “raindrop it”:

      Duran: Fucking Unc’s is here.

      Birch:    Oh yeah.

      Duran: Yeah.

      Birch:    That’s crazy.

      Duran: Fucking happy as a motherfucker.

      Birch:    When did he get

      Duran: Raindrops, drop tops.

      Birch:    Raindrops?

      Duran: (Unintelligible) its super, super raindrop.

      Birch:    Yeah right.

      Duran: I swear, on everything.

      . . . .

      Duran: Where you gonna be at [at 4 pm]

      Birch:    I’ll be in the hood. You already know where I’m gonna
                be at.

      Duran: Alright cause fucking ah I want you to raindrop it.

Govt. Exh. 9a at 57–58.


                                      4
     In another call that evening, Mr. Birch supplied directions to Mr.

Duran for a meeting. As Mr. Duran drove, Mr. Birch noted that he was

“about to see that gooey, gooey”:

     Duran: Motherfucker all I do is work.

     Birch:   Yeah all you do, sell bull shit work.

     Duran: Yeah right motherfucker. Fuck you.

     Birch:   (Laughs)

     Duran: We’re about to see bull shit work.

     Birch:   Yeah I’m about to see that gooey, that gooey, gooey.

     Duran: Yeah right motherfucker.

     Birch:   That goo. . . .

     Duran: After this you’re gonna be like where you at bro, bro.
            (Laughs)

Govt. Exh. 13a at 70–71.

     2.    Mr. Duran and Mr. Birch meet later the same day for about
           1-1/2 hours.

     The government also presented testimony from law-enforcement

officers about their visual surveillance of Mr. Duran and Mr. Birch. On

March 8, 2017, the officers saw the two men meet at an apartment complex

for about 1-1/2 hours.




                                     5
       3.   Mr. Duran later acknowledges that he still had the “hard”
            given to him by Mr. Birch.

       Three days later, Mr. Duran acknowledges that he still had the “hard”

given by Mr. Birch:

       Duran: Unc’s is supposed to be, I’m supposed to meet him
              when I leave out of here, but I still got that, that one
              and a heezy still.

       Birch:   What the hard that I gave you?

       Duran: Yeah, you want that you don’t have to fucking do
              nothing to it just get on it.

Govt. Exh. 14a at 84.

       4.   Testimony defines the terms used: “Gooey, gooey” and
            “raindrops” refer to the upcoming conversion of powder
            cocaine into crack cocaine, and Mr. Duran’s expression of
            happiness refers to the quality of Unc’s cocaine.

       Law-enforcement officers testified about the meaning of the terms

used in these calls. According to this testimony, Unc was Mr. Duran’s

supplier, “gooey, gooey” and “raindrops” referred to the making of crack

cocaine, and “hard” was code for crack cocaine. The officers also testified

that

           Mr. Birch was poking fun at the quality of the cocaine that Mr.
            Duran had previously furnished and

           Mr. Duran was telling Mr. Birch that the quality of this cocaine
            would leave him wanting more of it.




                                       6
     5.    Mr. Duran challenges the sufficiency of evidence showing
           his actual possession on March 8.

     Mr. Duran argues that this combination of evidence was insufficient

because there was no physical evidence of the drugs or testimony from

anyone who had seen Mr. Duran with the cocaine. According to Mr. Duran,

the government showed only that Unc had possessed cocaine, not that he

had given it to Mr. Duran.

     6.    Our prior opinions recognize two categories of evidence: one
           is sufficient to show possession, the other insufficient.

     We have previously addressed the sufficiency of the evidence of drug

possession in the absence of controlled purchases or actual observation of

the drugs. Our prior cases address

          recorded calls when the defendant expects to obtain drugs and

          recorded calls when the defendant acknowledges possession of
           the drugs.

Our case does not comfortably fit entirely into either category.

     a.    The government needed to present circumstantial or direct
           evidence of possession on March 8.

     Regardless of the category, the government needed to present either

direct evidence of drug possession or “enough circumstantial evidence to

support an inference that the defendant actually did possess the drugs in




                                      7
question” on March 8. United States v. Baggett, 

, 1096 (10th

Cir. 1989).

     b.       Circumstantial evidence is insufficient if the jury could not
              reasonably infer actual possession on March 8.

     Mr. Duran argues that

             the government presented no testimony showing that he had
              obtained the cocaine on March 8 and

             guilt requires direct or circumstantial evidence linking him to
              an observed illegal substance.

For this argument, Mr. Duran compares the government’s proof to the

evidence that we regarded as insufficient in United States v. Baggett and

United States v. Hall.

     In Baggett, the government presented

             recordings of three telephone calls indicating that the defendant
              had arranged to buy illegal drugs,

             testimony that law-enforcement officers had seen the defendant
              meet a suspected drug dealer, and

             the defendant’s acknowledgment of drug use during a one-
              month period.

, 1096-97 (10th Cir. 1989). We concluded that this

combination of evidence did not reasonably support a finding that the

defendant possessed the drugs on the pertinent date. 

Hall, the government presented

             telephone calls in which the defendant and a drug dealer
              discussed the price of drugs and agreed to meet and

                                        8
           video surveillance showing that the defendant had briefly
            entered the drug dealer’s car.

, 1307 (10th Cir. 2007). We concluded that this evidence did

not show possession of drugs on the pertinent date. 

      c.    The circumstantial evidence may suffice even if it does not
            include observation of illegal drugs.

      Mr. Duran points out that the government did not present evidence of

a controlled buy or observation of drugs on March 8. Given the absence of

this evidence, Mr. Duran contends that the government’s proof was

insufficient.

      For this contention, Mr. Duran points out that in Baggett, the court

said that a conviction must include “testimony linking defendant to an

observed substance that a jury can infer to be a narcotic.” Appellant’s

Opening Br. at 18–19 (emphasis in original) 

). To

interpret this passage, we consider the context. See Illinois v. Lidster, 

, 424 (2004) (stating that the Supreme Court often reads general

language in opinions “as referring in context to circumstances similar to

the circumstances then before the Court and not referring to quite different

circumstances that the Court was not then considering”); see also Wisehart

v. Davis, 

, 326 (7th Cir. 2005) (“Judges expect their

pronunciamentos to be read in context.”).




                                      9
     This passage appeared in the court’s discussion of a surveillance

operation. Law-enforcement officers had watched the defendant meet with

a suspected drug dealer, and the government argued that evidence of the

meeting could prove drug possession. The court rejected this argument,

remarking that the officers had not seen any illegal drugs. 

With this remark, the court did not purport to announce a blanket

requirement for testimony by someone who had seen the drugs. Indeed, the

Baggett court elsewhere acknowledged that circumstantial evidence of

possession could include

          proof of “secrecy or deviousness” or

          use of code words when referring to a substance.

would make little sense if the Baggett court had meant

to require observation of the drugs whenever possession is an element. 2 In

context, the Baggett court was referring to the importance of an “observed

substance” when the government’s evidence involves physical surveillance.




2
      In the next paragraph, the Baggett court discussed United States v.
Iacopelli, where the Second Circuit had regarded the evidence of
possession as sufficient based on records showing that the defendant
purchased and received controlled substances from a medical supplier. 

, 161 (2d Cir. 1973). The Baggett court distinguished Iacopelli on
the grounds that “[s]uch strong circumstantial evidence is not present in
this 

. But Iacopelli’s “strong circumstantial
evidence” did not include an “observed substance.” 

      Direct evidence can include a contemporaneous
               acknowledgement of possession.

      Observation of illegal drugs is also unnecessary when the

government presents direct evidence of possession. An example appears in

United States v. Marquez, where we held that the government had

sufficiently proven possession based on recorded telephone calls despite

the absence of any testimony involving observation of drugs or controlled

buys. 

, 1044 (10th Cir.), cert. denied, 

(2018).

In Marquez, we treated the recorded calls as direct evidence of possession.

      There the government presented a recording of a telephone call

between the defendant and a drug dealer. 

call, the defendant and

drug dealer used code language to discuss the distribution of

methamphetamine. For one batch of methamphetamine, the defendant said:

“I still have it.” 

another batch, he said: “I haven’t even got to

that yet.” 

that these statements constituted direct evidence of

drug possession: “If the jury believed Marquez’ statements that he ‘still’

had the low-quality methamphetamine and ‘ha[d]n’t even got[ten] to’ the

high-quality methamphetamine, no further inference was necessary to




                                      11
conclude that he possessed methamphetamine.” 

further

inference was necessary, the evidence was considered direct. 

case lacks direct evidence but has greater
             circumstantial evidence than was in Baggett or Hall.

      In contrast, the evidence against Mr. Duran was indirect. From the

first call on March 8, the jury could reasonably infer three facts:

      1.     Unc had brought powder cocaine and planned to give it to Mr.
             Duran.

      2.     Mr. Duran expected to get the powder cocaine from Unc.

      3.     Mr. Duran was arranging for Mr. Birch to convert the powder
             cocaine into crack cocaine.

But more was needed to infer that Unc had given the powder cocaine to

Mr. Duran.

      The need for additional circumstantial evidence distinguishes this

case from Marquez. There too no one testified about seeing the illegal

drugs. But the defendant was heard saying that he still had “it,” referring

to the drugs. See p. 11, above. Given this express statement of current

possession, the evidence against the Marquez defendant was considered

direct. See p. 11, above. Here, though, Mr. Duran never expressly

acknowledged in the call that he had obtained the cocaine from Unc. Thus,

the first recorded call on March 8 does not constitute direct evidence of

Mr. Duran’s possession on March 8.




                                      12
     But other circumstantial evidence against Mr. Duran could lead to a

reasonable inference that he had obtained the cocaine from Unc. While

driving to Mr. Birch’s apartment complex, Mr. Duran and Mr. Birch talked

on the telephone for roughly eighteen minutes. During this call, the only

audible voices were theirs and no one mentioned Unc’s presence. See Gov.

Exh. 13a. Mr. Duran told Mr. Birch: “We’re about to see bull shit work.”

And Mr. Birch replied: “Yeah I’m about to see that gooey, that gooey,

gooey.” See p. 5, above. Law-enforcement officers explained that “gooey,

gooey” referred to the conversion of powder cocaine into crack cocaine.

     After Mr. Duran arrived, he spent roughly 1-1/2 hours with Mr.

Birch, which law-enforcement officers testified was enough time to convert

the powder cocaine into crack cocaine. Then, on March 11, Mr. Duran

acknowledged that he still had “the hard” (crack cocaine) that he had

obtained from Mr. Birch. Govt. Exh. 14a at 84.




                                     13
      Considering these additional facts, a jury could reasonably find that

on March 8, Mr. Duran had

           obtained powder cocaine from Unc,

           referred to the powder cocaine as “it” (in the statement “I want
            you to raindrop it”),

           brought the powder cocaine to a meeting with Mr. Birch,

           spent roughly 1-1/2 hours with Mr. Birch, converting the
            powder cocaine into crack cocaine, and

           received crack cocaine from Mr. Birch (which he still had three
            days later).

This is “enough circumstantial evidence to support an inference that the

defendant actually did possess the drugs in question” on March 8. United

States v. Baggett, 

, 1096 (10th Cir. 1989). We thus reject Mr.

Duran’s challenge to the sufficiency of the evidence on Count 22.

      C.    Counts 35 and 36: Use of a Telephone to Facilitate a Drug
            Offense on March 8 and 11, 2017

      Mr. Duran also challenges his convictions for using a telephone to

facilitate the commission of a drug offense on March 8 and March 11,

2017. See 21 U.S.C. § 843(b). According to Mr. Duran, he could not have

facilitated a drug offense

           on March 8 because the government had failed to prove that
            Unc gave the cocaine to Mr. Duran or

           on March 11 because the jury had found Mr. Duran not guilty
            of possessing cocaine that day.


                                     14
We reject these challenges.

     The government needed to prove that Mr. Duran had

          knowingly and intentionally used a telephone or other
           communications device

          to commit, cause, or facilitate any act constituting a drug
           felony.

United States v. Pickle, 

, 1257 (10th Cir. 2017). These

elements required proof that Mr. Duran’s use of a telephone made the

underlying drug crimes easier to commit. 

Duran could be guilty

of facilitation even if someone else had committed the underlying drug

crime. See United States v. Orihuela, 

, 1304 (11th Cir. 2003)

(“[O]ne of the elements of an offense under § 843(b) is the commission by

someone of an underlying controlled substance offense.”).

     The government presented sufficient evidence of Mr. Duran’s

facilitation of drug crimes on March 8 and 11. He had knowingly and

intentionally used a telephone, and the factfinder could reasonably infer

that the calls had helped Mr. Birch to buy cocaine and convert it into crack

cocaine.

     Mr. Duran argues that his partial acquittal suggested that the jury

hadn’t believed that he possessed cocaine on March 11. But an acquittal on

the underlying drug crime does not prevent a conviction on the facilitation

charges. See United States v. Powell, 

, 64–65 (1984) (holding

that a defendant can be convicted of telephone facilitation despite an
                                     15
acquittal on the predicate felony); see also United States v. Milton, 

, 1294 (10th Cir. 1995) (“[T]he Supreme Court has held that even if a

defendant is acquitted on the underlying felony, a facilitation conviction

may still stand.”). 3 The factfinder could thus reasonably conclude that Mr.

Duran had facilitated commission of a drug crime on March 11 as well as

on March 8.

3.   The district court acted within its discretion in allowing Officer
     Fania to testify about controlled buys from Mr. Birch.

     Officer Frank Fania briefly testified about a confidential informant’s

controlled buys from Mr. Birch in March 2016 and January 2017. Mr.

Duran argues that the testimony should have been excluded based on




3
      In his reply brief, Mr. Duran argues that the government failed to
prove the possession of any drugs on March 11, foreclosing the possibility
that Mr. Duran could have facilitated the commission of a felony on that
day. But Mr. Duran did not make this argument in his opening brief. There
he had relied solely on his acquittal on Count 24, which charged
distribution and possession of cocaine with intent to distribute 28 grams or
more of a substance containing cocaine base (crack cocaine) on March 11.
Expanding the argument in his reply brief was too late. United States v.
Mendoza, 

, 1260–61 (10th Cir. 2006).

                                     16
irrelevance, unfair prejudice, hearsay, and lack of personal knowledge. We

reject these arguments.

      A.    Standard of Review

      We review the district court’s evidentiary rulings for an abuse of

discretion. United States v Banks, 

, 1023 (10th Cir. 2018).

      B.    Relevance and Unfair Prejudice

      In applying the abuse-of-discretion standard, “we give the evidence

its maximum reasonable degree of relevance and its minimum reasonable

danger of unfair prejudice.” United States v. Tee, 

, 1273

(10th Cir. 2018). The district court may then exclude the evidence if the

danger of unfair prejudice substantially outweighs the probative value.

United States v. Silva, 

, 712 (10th Cir. 2018), cert. denied,

(2019).

      Officer Fania testified about the investigation of Mr. Birch and

described the events triggering the investigation of Mr. Duran. During the

investigation of Mr. Birch, Officer Fania was in charge of the surveillance.

The district court could reasonably regard his testimony as relevant.

      The prosecution can ordinarily present overview testimony

describing the start of, and techniques in, the investigation. United States

v. Brooks, 

, 930 (10th Cir. 2013). Here, for example, an

overview could help the jury understand the content and significance of the

conversations between Mr. Duran and Mr. Birch. These conversations

                                      17
include language that Mr. Birch had previously used when referring to

cocaine and its conversion into crack cocaine. Given this prior use of

language, the jury could reasonably infer that the code words had shown

involvement in converting powder cocaine into crack cocaine.

      Mr. Duran also contends that even if the testimony had been relevant,

it would have created unfair prejudice. The testimony might have been

unfairly prejudicial if it had suggested guilt by association, unfairly

impugned the defendant’s credibility, or included statements unsupported

by personal knowledge. See United States v. Banks, 

, 1023

(10th Cir. 2018). But the district court could reasonably regard these

dangers as absent, for the government did not use Mr. Birch’s prior drug

sales to

           show that Mr. Duran had possessed or sold cocaine in March
            2017 or

           impugn Mr. Duran’s credibility.

See United States v. Banks, 

, 1024 (10th Cir. 2018) (upholding

the admissibility of overview testimony that had not included an opinion

on the witnesses’ trustworthiness or guilt). The district court could thus

reasonably conclude that Officer Fania’s overview testimony had not

created unfair prejudice.




                                      18
     C.    Hearsay

     Mr. Duran also regards Officer Fania’s testimony as inadmissible

hearsay. 4 We disagree.

     At trial, Mr. Duran raised only one hearsay objection to Officer

Fania’s testimony. The government asked Officer Fania: “What about those

controlled purchases you had talked about?” R., vol. III, at 107. 5 Mr. Duran

objected, and the district court overruled the objection. Officer Fania

answered without referring to any out-of-court statements:

     A.    We were using an informant who made a controlled
           purchase from Jerrell Birch that day.

     Q.    On March 11th?

     A.    Correct. March 11, 2016.

     Q.    And I apologize. I might have -- I might have
           misunderstood you. Did you say there were two in March
           of 2016?

     A.    There were.

     Q.    So March 11th, and what was the other day?

     A.    I believe the second one was March 25th.

4
      In a footnote, Mr. Duran also contends that Officer Fania’s testimony
violated the Confrontation Clause. Appellant’s Opening Br. at 33 n.9. This
contention was inadequately developed. See United States v. Hardiman,

, 1131 (10th Cir. 2002) (en banc) (“Arguments raised in a
perfunctory manner, such as in a footnote, are waived.”).
5
      Officer Fania had previously testified that the agents were working
with a confidential informant who could make a controlled buy from Mr.
Birch. See R., vol. III, at 96.

                                      19
      Q.    And you indicated you used a confidential human source?

      A.    Correct.

      Q.    Were the steps that you previously described as to both of
            these purchases used?

      A.    They were all of them used.

      Q.    Okay. So it was audio-recorded and surveillance observed
            these?

      A.    That is correct.

      Q.    And transpired during those controlled purchases in terms
            of the deal?

      A.    The informant made phone contact with Jerrell. Ultimately
            they met, and on, I believe, March 11th purchased -- or the
            informant purchased one ounce of crack cocaine. On the
            second one, on March 25th, the informant purchased two
            ounces of crack cocaine from Jerrell Birch?

      Q.    And so did those controlled purchases further your
            investigation of Jerrell Birch?

      A.    They absolutely did.

Given the absence of any mention of an out-of-court

statement, the district court acted within its discretion in overruling the

hearsay objection. After this exchange, Mr. Duran never lodged another

hearsay objection to Officer Fania’s testimony.

      Despite the absence of further objection, Mr. Duran suggests that

some of the follow-up questions elicited hearsay. Hearsay consists of an

out-of-court statement offered for the truth of the matter asserted. Fed. R.


                                      20
Evid. 801(c). But a law-enforcement officer’s “out of court statements are

not hearsay when offered for the limited purpose of explaining why a

Government investigation was undertaken.” United States v. Freeman, 

, 563 (10th Cir. 1987).

      Mr. Duran suggests that some of the follow-up questions went

beyond this limited purpose. 6 But Mr. Duran does not identify any

improper questions. See United States v. Marquez, 

, 1052

(10th Cir. 2018) (stating that the issue was inadequately briefed when the

defendant broadly challenged the introduction of overview testimony

without identifying any particular testimony that had been improperly

admitted or explaining why that particular testimony had been

inadmissible). Rather than identify any improper questions, Mr. Duran

states that Officer Fania “told the jury that the confidential source [had]

engaged in three controlled buys with Mr. Birch prior to Mr. Duran’s

alleged involvement in the conspiracy.” Appellant’s Opening Br. at 30. But

Mr. Duran does not identify any of the informant’s hearsay statements. 7


6
      Mr. Duran also contends that if the testimony had a limited purpose,
the district court should have given a limiting instruction. But Mr. Duran
did not request a limiting instruction, and the district court did not err in
declining to give one sua sponte. See United States v. Record, 

, 1376 (10th Cir. 1989) (“[I]t is not error for a trial court to fail to
[issue a limiting instruction] in the absence of a request by counsel.”).
7
      Mr. Duran argues that the testimony could constitute hearsay even if
Officer Fania hadn’t identified the informant’s actual statements.
Appellant’s Opening Br. at 31–32. For this argument, Mr. Duran relies on a
                                      21
      Mr. Duran contends that even if Officer Fania hadn’t recited the

actual statements, he narrated the substance of what the informant had

said. But Mr. Duran does not identify a single out-of-court statement

recollected by Officer Fania. And even if Mr. Duran had identified the

purported hearsay testimony, he forfeited further hearsay arguments

because he never asserted another hearsay objection to any of the questions

put to Officer Fania. See United States v. Norman T., 

, 1106

(10th Cir. 1997). 8

      D.    Lack of Personal Knowledge

      Mr. Duran argues that Officer Fania lacked personal knowledge of

the controlled buys from Mr. Birch. This argument is unpreserved and

invalid.

      We address preservation in our local rules. Rule 28.1(A) requires

appellants to cite in the record where the issue was raised and decided. Mr.


First Circuit opinion: United States v. Meises, 

, 22 n.25 (1st Cir.
2011). But we have declined to follow Meises. See, e.g., United States v.
Fletcher, 497 F. App’x 795, 804–05 (10th Cir. 2012) (unpublished)
(declining to follow Meises and upholding law-enforcement testimony
about the roles played by various participants in illegal activities); see also
United States v. Marquez, 

, 1051–52 (10th Cir. 2018)
(stating that Meises does not “establish the well-settled law of this
circuit”).
8
      Despite the forfeiture, Mr. Duran could have argued plain error.
United States v. Kearn, 

, 1313 (10th Cir. 2017). But he
didn’t. See 

consider a forfeited contention based on the
failure to urge plain error).

                                      22
Duran complied with this rule by citing Volume III, pages 107–09. But

these pages do not contain any objection to Officer Fania’s testimony

based on a lack of personal knowledge. Indeed, we have scoured the record

and find no objection to Officer Fania’s testimony based on a lack of

personal knowledge.

      Mr. Duran did object to one question on the ground that it called for

hearsay. See p. 19, above. But the rules governing hearsay and personal

knowledge are distinct and address different evidentiary defects. See

United States v. Mandel, 

, 1369 (4th Cir. 1979) (discussing

the differences between the rules addressing hearsay and personal

knowledge); Agfa-Gevaert, A.G. v. A.B. Dick Co., 

, 1523

(7th Cir. 1989) (“Knowledge acquired through others may still be personal

knowledge within the meaning of Fed. R. Evid. 602, rather than hearsay,

which is the repetition of a statement made by someone else—a statement

offered on the authority of the out-of-court declarant and not vouched for

as to truth by the actual witness.”). So the assertion of a hearsay objection

did not preserve an argument that Officer Fania lacked personal

knowledge. See Schulenberg v. BNSF Rw. Co., 

, 1288 n.6

(10th Cir. 2018) (concluding that the appellant’s objection on hearsay

grounds failed to preserve an objection involving a lack of personal

knowledge).



                                      23
      Even if Mr. Duran had preserved the objection, however, it would

have failed. The foundational requirement for personal knowledge “is not

difficult to meet.” United States v. de Lopez, 

, 1132 (10th

Cir. 2014). The district court considers only whether “a rational juror

could conclude based on a witness’s testimony that he or she has personal

knowledge of a fact.” 

testified that he had participated in the arrangements

for the controlled buys. Given this testimony, the district court had the

discretion to find personal knowledge for Officer Fania’s testimony about

the controlled buys. See United States v. Marquez, 

, 1049

(10th Cir. 2018) (holding that an officer’s knowledge of recorded

conversations provided personal knowledge). 9 We would thus reject this

appellate argument even if it had been preserved.

4.    The district court acted within its discretion in allowing Officer
      Rossi to testify about the meaning of recorded calls.

      After the government played recordings of calls in February 2017 and

on March 8, 2017, Officer Rossi interpreted some of the language. On


9
      The government points out that Officer Fania testified as one of the
two case agents, using the first-person “we” to describe what his team of
investigators had done. In response, Mr. Duran denies that Officer Fania’s
use of the pronoun “we” was enough to show personal knowledge. But a
rational factfinder could conclude that Officer Fania, as one of the two
case agents, knew what his team of investigators had done. See United
States v. Decoud, 

, 1012 (9th Cir. 2006) (concluding that a
case agent had personal knowledge based on his participation in the
surveillance and interactions with a confidential informant).
                                     24
appeal, Mr. Duran argues that the testimony was inadmissible because

Officer Rossi had improperly (1) expressed an opinion on Mr. Duran’s

guilt, (2) based his opinion on inadmissible hearsay, and (3) expressed

views that were unfairly prejudicial. We reject these arguments.

     A.    Calls in February 2017

     For the calls in February 2017, Officer Rossi testified that

          Mr. Duran appeared to be trying to collect money from Mr.
           Birch and

          the discussion of “putting it in the water” suggested drug
           dealing.

Mr. Duran did not object to any of this testimony. As a result, he forfeited

his current appellate challenge to this part of the testimony. United States

v. Wardell, 

–10 (10th Cir. 2009). Though we could entertain

an argument involving plain error, Mr. Duran has not urged plain error. See

note 8, above. We would thus ordinarily decline to consider this argument.

See note 8, above.

     But Mr. Duran’s appellate argument would fail even if he had

preserved the challenge. If the challenge had been preserved, we would

apply the abuse-of-discretion standard. United States v. Comanche, 

, 1266 (10th Cir. 2009). Applying this standard, we would

consider Officer Rossi’s testimony, which had used the recorded calls to

explain why his team broadened the investigation to include Mr. Duran.



                                     25
     Mr. Duran argues that Officer Rossi was improperly providing his lay

opinion about the conspiracy and the reliability of the investigation. But

Mr. Rossi did not testify about his conclusions from the February calls; he

simply explained why investigators had turned their attention to Mr.

Duran. See United States v. Warman, 

, 348 (6th Cir. 2009)

(concluding that law-enforcement officers’ testimony, which identified the

defendant as a supplier, had been relevant and not unfairly prejudicial

because the testimony had “explained the reason for the government’s

investigation” of the defendant and others). So even if Mr. Duran had

objected, the district court would have had the discretion to permit this

part of Officer Rossi’s testimony.

     B.     Calls on March 8, 2017

     Officer Rossi also testified about his interpretation of five calls made

on March 8, 2017. According to Officer Rossi, these calls showed that Mr.

Duran had obtained cocaine from Unc, arranged to meet Mr. Birch, and

provided Mr. Birch with cocaine. In Officer Rossi’s view, two later

telephone calls confirmed that the two men had met on March 8 to convert

the powder cocaine into crack cocaine. Mr. Duran contends that the

testimony improperly communicated Officer Rossi’s opinions on guilt and




                                     26
the meaning of code words, was based on hearsay, and was unfairly

prejudicial. We reject these contentions.

     1.    Opinions on Guilt and the Meaning of Code Words

     Mr. Duran contends that Officer Rossi improperly testified about his

own beliefs of Mr. Duran’s guilt and the meaning of code words. We reject

these contentions.

     According to Mr. Duran, this testimony improperly waded into guilt

or innocence, a matter reserved for the jury. We reject this argument.

     Law-enforcement agents can ordinarily testify that the defendants

were engaged in drug trafficking because this testimony constitutes

opinion evidence on a fact issue. See United States v. Barbee, 

, 1031–32 (10th Cir. 1992); see also United States v. Marquez, 

, 1048–49 (10th Cir. 2018) (holding that a law-enforcement

officer could testify about a defendant’s role as a drug distributor because

the testimony was factual and objectively based on the officer’s knowledge

of recorded telephone calls).

     Mr. Duran contends that Officer Rossi went too far by expressing his

belief that Mr. Duran was guilty. We disagree with this characterization of

the testimony. Officer Rossi simply explained why he had turned his

attention toward Mr. Duran: After surveilling Mr. Birch and listening to

his calls, Officer Rossi broadened the investigation because he thought that

Mr. Duran would help Mr. Birch convert the powder cocaine into crack

                                     27
cocaine. See United States v. MacKay, 

, 838 (10th Cir. 2013)

(holding that the district court did not err in allowing an expert witness to

testify about her observation based on the evidence rather than simply tell

the jury what result to reach). Officer Rossi thus framed his opinion in the

past tense by referring to his earlier beliefs based on what he had observed:

      On March 8, based on the calls, I believed that Mr. Duran was
      going to meet Mr. Birch at his residence on Paris -- at 1650 Paris.
      During that, Mr. Duran was going to provide Mr. Birch with what
      Unc’s had provided him, which we believed -- and other
      investigators as well believed that Mr. Birch was going to assist
      Mr. Duran in making crack cocaine from the powder cocaine
      received from Unc’s.

R., vol. III, at 330–31 (emphasis added). The district court did not abuse

its discretion by allowing Officer Rossi to testify about how his earlier

beliefs had led the officers to broaden their investigation.

      Officer Rossi also testified about the meaning of code words used by

Mr. Duran and Mr. Birch. The district court did not err in allowing this

testimony, for it could reasonably be considered a lay opinion based on

information learned through the investigation. See United States v. Cheek,

, 447–48 (7th Cir. 2014) (holding that an agent’s testimony

about the meaning of drug-code words was admissible as a lay opinion

based on personal observations and perceptions derived from his

investigation); see also United States v. Akins, 

, 599 (5th Cir.

2014) (“[T]estimony about the meaning of drug code words can be within



                                      28
the proper ambit of a lay witness with extensive involvement in the

underlying investigation.”).

     2.    Hearsay

     Mr. Duran also argues that Officer Rossi based his testimony on

hearsay. But Mr. Duran forfeited this argument by failing to lodge a

hearsay objection to Officer Rossi’s testimony about the March 8 calls. See

p. 22, above. We could ordinarily consider the possibility of plain error.

See note 8, above. But Mr. Duran has not alleged plain error, so we decline

to consider Mr. Duran’s appellate challenge. See note 8, above.

     3.    Unfair Prejudice

     Mr. Duran also contends that the testimony was unfairly prejudicial

because the jury might have accepted Officer Rossi’s testimony “as

gospel.” Appellant’s Opening Br. at 43. For this contention, the district

court considers whether the danger of unfair prejudice substantially

outweighs the testimony’s relevance. Fed. R. Evid. 403. In addressing this

inquiry, we give the evidence its “maximum reasonable degree of relevance

and its minimum reasonable danger of unfair prejudice.” United States v.

Tee, 

, 1273 (10th Cir. 2018); see p. 17, above.

     Viewing the evidence in this light, we conclude that the district court

need not have viewed the unfair prejudice as substantially greater than the

testimony’s relevance. The calls on March 8 used peculiar language that

would have made little sense in the absence of guidance about how Mr.

                                     29
Duran and Mr. Birch had communicated with one other. The district court

could thus reasonably conclude that the testimony was admissible despite

the possibility of unfair prejudice. See United States v. Valbrun, 

, 444–45 (1st Cir. 2017) (concluding that the district court had the

discretion to find lay testimony about drug-code words admissible and

rejecting an appellate argument based on the danger of unfair prejudice).

      The district court also took measures to ensure that the jury viewed

Officer Rossi’s testimony with the proper perspective. During the

testimony, the court told the jury that

            Officer Rossi was “reaching conclusions as the case agent,
             which explain where he’s coming from in this case” and

            the jury was “to decide if they agree with him.” 10

And after the close of the evidence, the district court instructed the jury to

“[r]emember at all times that [they were] judges of the facts” and were to

decide if the government had proven guilt “beyond a reasonable doubt.” 11

      Given these instructions, Officer Rossi’s testimony did not impede

the jury’s assessment of the evidence. The district court thus did not abuse

its discretion in overruling Mr. Duran’s objection involving unfair

prejudice.




10
      R., vol. III, at 311.
11
      R., vol. I, at 329.
                                       30
                                    * * *

      In summary, the district court did not err in allowing Officer Rossi to

testify about the meaning of the recorded calls. Mr. Duran forfeited his

appellate argument about the calls recorded in February 2017. For the calls

recorded on March 8, 2017, the district court acted within its discretion in

allowing the testimony.

5.    The district court acted within its discretion in allowing Agent
      Peterson to testify about coded language.

      Finally, Mr. Duran contends that the district court erred in admitting

expert testimony by Agent Donald Peterson. The government presented

Agent Peterson as an expert on drug-trafficking trends, patterns, and

communications. Mr. Duran objected to Agent Peterson’s qualifications as

an expert on drug dealers’ use of code language. The district court

overruled the objection, concluding that “by training and experience

[Agent Peterson] has sufficient expertise to at least be permitted to express

opinions.” R. vol. III, at 444.

      With this objection overruled, Agent Peterson testified that drug

dealers typically do not use the words “crack” or “cocaine” when speaking

on the telephone, noting that drug dealers often use code words like

“bread,” “loot,” “paperwork,” “titles” (money), “rack” (a thousand

dollars), “work” (cocaine), “soft” (powder cocaine”), “hard” (crack

cocaine), “heezy” (half of a kilogram or half of an ounce), “raindrop,” and


                                     31
“gooey, gooey” (the process of converting cocaine into crack cocaine). See

R., vol. III, at 462–64, 484, 487–88.

      Mr. Duran argues that

           the district court failed to make adequate findings on the
            reliability of the testimony and

           Agent Peterson was not qualified to testify about the use of
            code language.

Mr. Duran observes that Agent Peterson had never testified as an expert in

a jury trial, had never spoken about the term “raindrops,” had not

remembered speaking about the term “heezy,” and had not relied on any

publications.

      The district court must act as a gatekeeper, ensuring that the

proffered opinions rest on a reliable foundation and are relevant to the

issues. United States v. Roach, 

, 1206 (10th Cir. 2009).

Although “the gatekeeper inquiry under Rule 702 is ultimately a flexible

determination, . . . a district court, when faced with a party’s objection,

must adequately demonstrate by specific findings on the record that it has

performed its duty as gatekeeper.” Goebel v. Denver & Rio Grande W. R.R.

Co., 

, 1088 (10th Cir. 2000).

      We consider de novo whether the court applied the proper standard

for allowing expert testimony and made sufficient findings. 

. We then determine whether the rulings fell within the district

court’s discretion. 

district court’s findings were adequate. The court found

sufficient expertise based on Agent Peterson’s training and expertise; more

detailed findings were not required. See, e.g., United States v. Cui Qin

Zhang, 

, 1129 (10th Cir. 2006).

      These findings were supported by the record. Agent Peterson had

extensive experience with drug trafficking cases: over 16 years’ experience

in law enforcement, including observation of 75 to 100 drug deals and

more than 50 controlled buys. In light of this experience, the district court

acted within its discretion in allowing Agent Peterson to testify about the

use of coded language.

6.    Conclusion

      We thus affirm Mr. Duran’s convictions.




                                      33