                          REVISED MARCH 17, 2003
                      UNITED STATES COURT OF APPEALS
                           For the Fifth Circuit



                               No. 02-40208



                        United States of America,

                                                        Plaintiff/Appellee,


                                   VERSUS


      Fredi Neptal Ramirez-Velasquez; David Villarreal-Lara,

                                                  Defendants/Appellants.



           Appeal from the United States District Court
                For the Southern District of Texas

                            February 21, 2003


Before JOLLY, DUHÉ, and WIENER, Circuit Judges.

DUHÉ, Circuit Judge:

      Following a jury trial, Fredi Neptal Ramirez-Velasquez and

David Villarreal-Lara were convicted of possession with intent to

distribute marijuana in violation of 21 U.S.C. §§ 841(a)(1) and

(b)(1)(B), and Villarreal-Lara was convicted of conspiracy in

violation of 21 U.S.C. § 846.      Both defendants appeal.       We affirm.

I. FACTUAL AND PROCEDURAL HISTORY

      Fredi Neptal Ramirez-Velasquez (“Ramirez”) worked as a driver

for   Kaizen   Auto   Transport,   a   company   that    receives   Chrysler
vehicles manufactured in Mexico, then distributes them to U.S.

dealers by truck.       The Kaizen facility consists of two lots, side

by side, surrounded by security fencing.            On one lot is   a parking

lot, on which the vehicles to be delivered are stored, and the

Kaizen office building, which contains offices and a room used by

the Kaizen drivers.       The second lot is demarcated by a line of

trees and was used primarily to store auto transport vehicles. The

gated   entrance   to    the   facility   is   situated     near   the   office

building, and security guards are posted near the office building

at night and on weekends.

     Vehicles arriving from the factory are inspected for damage

and then catalogued onto dispatch sheets; each dispatch sheet lists

the vehicles to be delivered and their destination. Kaizen drivers

select delivery destinations on a first-come, first-served basis.

When a driver selects a dispatch sheet, the security guards record

the vehicle identification numbers of the assigned vehicles, and

the driver must inspect the vehicles for damage or shortages.               The

driver then   loads      the   vehicles   on   an   auto   transport     vehicle

(“transport”) and delivers them to the dealer.

     Transports are tractor-trailers on which six or seven vehicles

can be loaded.     The method used to load a transport is to load the

top tier of the transport, then raise it with hydraulic lifts and

load the bottom tier.      The structure of the transport is such that

one wishing to access a vehicle on the top tier after it has been

raised must climb up and hold on—there is very little room to

                                      2
stand.

       One Sunday, Ramirez arrived to work at 8 a.m.                Armando

Velasquez and Hector Soto (“Soto”), Kaizen security guards, were

the only other people at the facility.              Ramirez obtained his

dispatch sheet and then made a call from a phone in the drivers’

room. Soto overheard Ramirez state that he needed “liquid.” Phone

records indicate that the call from the drivers’ room was placed at

8:07    a.m.   to   a   cellular   phone   owned   by   David    Villarreal-

Lara(“Villarreal”), a mechanic for Kaizen.

       Villarreal was on call seven days a week, twenty-four hours a

day.    That notwithstanding, he rarely worked weekends; in the two

years that Soto had been a weekend security guard for Kaizen, he

had seen Villarreal only four times. John Bannerman (“Bannerman”),

a Kaizen safety supervisor, served as the backup on-call mechanic,

and often worked weekend service calls in Villarreal’s place. This

day, however, Villarreal did report to the Kaizen facility in

response to Ramirez’s call.

       Ramirez’s habit in loading his auto transport was to pull the

transport into the loading area situated near the Kaizen office

building and the security guards’ post.        Once in the loading area,

Ramirez would retrieve and inspect one vehicle, load it onto the

transport, and then retrieve and load another.                  On this day

however, Ramirez did not pull his transport to the loading area;

instead he drove it to the second lot and parked it behind the

trees, which obscured the security guards’ view of the transport.

                                      3
      After completing his phone call, Ramirez went to his transport

and began loading. Shortly thereafter, Soto saw a large van arrive

and proceed to the area where Ramirez had parked his transport.

Between five and ten minutes after the van arrived, Villarreal

approached   the   Kaizen   office   building   and   greeted   Soto   and

Velasquez. He then retrieved the service truck, which housed tools

used for maintenance of transports, and returned to Ramirez’s

transport. Some time later, Villarreal returned the service truck,

told Soto that he had fixed a flat tire on Ramirez’s transport, and

got into the passenger side of the van, which left the facility.1

Ramirez finished loading his transport and left it to run errands

before embarking on his route.

      The next person to arrive at the Kazien facility was John

Bannerman.    He noticed that the service truck had been used and

asked the security guards if anyone had been in the truck that day.

Upon learning of Villarreal’s morning visit, Bannerman decided to

inspect Ramirez’s transport and asked Soto to accompany him.

Bannerman climbed onto the transport and opened the door of one of

the trucks mounted on the top tier.      Inside he discovered a large

black duffel bag containing bales of marijuana.        Bannerman called

his supervisor, Cal McGaridge.       McGaridge arrived not long after

accompanied by Drug Enforcement Administration Agent Robert Perez.

Bannerman explained to Agent Perez what had happened, and he and


  1
      The driver of the van remains unidentified.

                                     4
Agent Perez watched Ramirez’s transport and awaited Ramirez’s

return.

     Ramirez returned to the facility at about 1:15 p.m., and after

brief preparations, left in the transport.              Agent Perez followed

Ramirez to a nearby Border Patrol checkpoint.             At the checkpoint,

Border Patrol Agent Scott McCauley inspected Ramirez’s transport.

On inspection of all the trucks on the top tier of the transport,

Agent McCauley discovered black duffel bags containing a total of

494.8 pounds, or 224.44 kilograms, of marijuana.              Agent McCauley

was able to inspect only the trucks on the top tier thoroughly; the

support structures of the top tier blocked the doors of the trucks

loaded on the bottom.        Looking through the windows of the trucks on

the bottom, Agent McCauley saw nothing.

     Agent Perez arrested Ramirez.               Though Ramirez now denies

confessing, Agent Perez’s version of events following the arrest is

as follows.    Ramirez confessed that he had been hired by an unknown

person to     smuggle   an    unknown   amount    of   marijuana   to   Dallas.

Ramirez said that earlier in the day two people had delivered the

marijuana in a van and helped him to load the marijuana onto his

auto transport.

     When arrested, Ramirez was in possession of Villarreal’s

cellular telephone, the same phone to which he had made the call

from the driver’s room telephone requesting “liquid.” Ramirez told

Agent Perez that he had received the phone when he took delivery of

the marijuana.     Agent Perez took possession of the phone after

                                        5
arresting Ramirez.          While Agent Perez held the phone, there were

eight incoming calls from 3:12 p.m. to 4:42 p.m., all from a Kaizen

cellular phone assigned to Villarreal.2             Agent Perez answered the

calls, but the caller hung up each time.

      After his arrest, Ramirez’s transport was returned to Kaizen.

The trucks were left on the transport, and a different driver

delivered them to the dealer the next day.                 While unloading the

vehicles,      the    Kaizen    driver     discovered     another   duffel   bag

containing marijuana in a vehicle on the bottom tier of the

transport.      After Ramirez’s transport was returned to the Kaizen

facility, Bannerman inspected it and found no evidence of a broken

hydraulic line, which he would expect to find if the transport had

needed hydraulic fluid.           Neither did Bannerman find evidence of a

flat tire, which had been Villarreal’s stated purpose in being at

the facility that morning.

      Ramirez and Villarreal were tried jointly for conspiracy and

possession     of     marijuana    with   intent   to    distribute.    Ramirez

testified in his own defense.             He denied confessing and testified

that he never saw a van that morning, that he called Villarreal

only because         his   transport   needed   maintenance—the     transport’s

hydraulics were malfunctioning and one of the tires, though it was

not flat, needed air—and that he was unaware that marijuana had

been hidden in vehicles on his transport.               Ramirez admitted having


  2
      Ex. 3.

                                           6
Villarreal’s cellular phone, but said that Villarreal had loaned

him the phone the week before.

     Ramirez was convicted only of the possession count, while

Villarreal was convicted on both counts. Both defendants appeal

their convictions, asserting various points of error.

II. DISCUSSION

A. Ramirez’s claims

     1. Improper prosecutorial remarks

     Central to Ramirez’s conviction was the jury’s conclusion that

he knew the marijuana was hidden in the trucks on his transport.

During closing arguments, counsel for Ramirez argued that the

government was prosecuting Ramirez despite knowing that he was

innocent:

  Why is the government trying to bring in information like that
  [referring to small details of events surrounding the arrest]
  or trying to stick that in your mind. Because they don’t have
  anything else. Because they know Fredi [Ramirez] didn’t know
  also, but they want to prosecute somebody. [Agent] Perez wants
  a conviction. Fredi did not know there was marijuana in that
  trailer.

     The Assistant U.S. Attorney’s (“AUSA”) response included the

following:

     Do the agents have any reason? Do they have a reason to
  throw away their career, to say, oh this load is just too much
  for me, I’m going to give up my twenty-year law enforcement
  career, because I really care that two people get convicted.
  They’re there to testify to the truth. They enforce the laws
  and they’re going to honor it.     And they’re going to say,
  these are the facts.
                             * * *

  I guess they want you to think that you we [sic] made this


                                 7
  whole thing up, that Agent Perez after twenty years in law
  enforcement, seven years as a special agent with the Border
  Patrol working out of DEA just— 3

      Defense counsel objected and moved for a mistrial, arguing

improper vouching for government witnesses by the prosecution. The

district      court    denied     the     motion      and    issued      no   curative

instruction.          However,    its    general      instructions       to   the   jury

included admonitions that the jurors are the sole appraisers of

witness      credibility    and    that    the   lawyers’       arguments     are     not

evidence.4

      Ramirez contends that the AUSA erred by vouching for Agent

Perez’s      credibility.        The    defendant     seeking     to   overturn       his

conviction      for    improper        remarks   by    the    prosecution       has     a

substantial burden.         United States v. Diaz-Carreon, 915 F.2d 951,

956   (5th    Cir.    1990);     prosecutorial        remarks    alone    rarely      are


  3
      2 R. at 183-84, 192.
  4
     The instructions in part state:
   Remember that any statements, objections, or arguments, made
   by the lawyers are not evidence. The function of the lawyers
   is to point out those things that are most significant or most
   helpful to their side of the case. . . .         In the final
   analysis,   however,   it   is  your   own   recollection   or
   interpretation of the evidence that controls in this case.
   What the lawyers say is not binding upon you.
                               * * *
   You are the sole judges of the credibility or the
   “believability” of each witness and the weight to be given the
   witness’s testimony. An important part of your job will be
   making judgment about the testimony of witnesses, including
   the defendant, who testified in this case. You should decide
   whether you believe what each person has to say and how
   important that testimony was.
2 R. at 142-43, 14.

                                           8
sufficient to warrant reversal.         United States v. Iredia, 866 F.2d

114, 117 (5th Cir.), cert. denied, 492 U.S. 921, 109 S.Ct. 3250,

106 L.Ed.2d 596 (1989).            To constitute reversible error, the

comments must not only be inappropriate but also must “affect

substantially the defendant’s right to a fair trial.” United States

v. Murrah, 888 F.2d 24, 27 (5th Cir. 1989).

      “It     is   particularly    improper,     indeed,    pernicious,    for   a

prosecutor to seek to invoke . . . the sanction of the government

itself as a basis for convicting a criminal defendant.” United

States v. Gallardo-Trapero, 185 F.3d 307, 320 (5th Cir. 1999)

(citations omitted).        The prosecutor’s vouching for government

witnesses vests them with “the imprimatur of the Government, and

may induce the jury to trust the Government’s judgment rather than

its own view of the evidence.”        United States v. Young, 470 U.S. 1,

18-19   (1985).       Equally     harmful   is   the   implication   that     the

prosecutor has reached a conclusion based on facts not in evidence.

Id.

      While prosecutorial vouching for government witnesses is never

desirable, Young recognized that to the extent the prosecutor’s

remarks are invited by similar remarks from the defense, we must

“not only weigh the impact of the prosecutor’s remarks, but must

also take into account defense counsel’s opening salvo.”                  Id. at

13.     The    prosecutor’s     response    will   not     necessarily    warrant

reversal, so long as it is designed merely to “right the scale.”

Id. at 12-13.

                                       9
      The trial judge, relying on Gallardo-Trapero, concluded that

the AUSA’s remarks did not warrant a mistrial.                  He reasoned that

the AUSA’s remarks were invited by defense counsel’s assertion that

the government knew Ramirez was innocent and counsel’s implication

that Agent Perez testified falsely out of desire for a conviction.

The judge noted that the AUSA had not referred to facts not in

evidence.5      He    also   estimated    that     the     remarks     we   found

inappropriate    in   Gallerdo-Trapero      were     more       provocative   and

stronger endorsements of the government witnesses than were this

prosecutor’s remarks.6

      Defense counsel’s attack on the government and Agent Perez was

certainly    inappropriate,    but   we   conclude       that    the   prosecutor

exceeded the range of response necessary to “right the scale.”                 As

we have stated before, “[t]he power and force of the government

tend to impart an implicit stamp of believability to what the

prosecutor says.” United States v. Garza, 608 F.2d 659, 663 (5th

Cir. 1988).     The AUSA was entitled to argue in response to the

defense attack that Agent Perez had no reason to lie, see United

  5
     In adverting to Agent Perez’s twenty-year law enforcement
career, the AUSA was referring to a fact in evidence — Agent Perez
had testified to his law enforcement experience.
  6
     Between defense counsel’s objections, the U.S. Attorney in
Gallardo-Trapero stated:
“I repeat, do you think that agents for the federal government and
a prosecutor for the federal government, for the United States of
America, are going to risk their career and get on the stand and
commit *** perjury and risk their career.      It’s not going to
happen, ladies and gentlemen.”
Gallardo-Trapero, 185 F.3d at 319 n.5

                                     10
States v. Munoz, 150 F.3d 401, 414 (5th Cir. 1998), but she went

too far in arguing that, as a rule, federal law enforcement agents

appear in court and tell the truth.

     We recognize the difficulty of fashioning a counterbalance to

inappropriate remarks by defense counsel.          As the Court in Young

noted, id. 470 U.S. at 13, and as the trial judge acknowledged, the

better alternative would be for the district judge to intervene at

the point of defense counsel’s remarks—or at least after their

conclusion—with   a   warning    and     a   curative   instruction,   thus

obviating the need for the prosecutor to respond.

     Having agreed that the AUSA’s remarks were inappropriate, we

turn to their effect on Ramirez’s substantial rights.         To gauge the

effect to Ramirez’s substantial rights, we must consider “(1) the

magnitude of the statement’s prejudice, (2) the effect of any

cautionary instructions given, and (3) the strength of the evidence

of the defendant’s guilt.”      United States v. Tomblin, 46 F.3d 1369,

1389 (5th Cir. 1995).

     The magnitude of prejudicial effect is measured by “looking at

the prosecutor's remarks in the context of the trial in which they

were made and attempting to elucidate their intended effect.”

United States v. Fields, 72 F.3d 1200, 1207 (5th Cir. 1996).            We

give substantial weight to the district court’s assessment of

prejudicial effect. Id.         After considering the effect of the

remarks, the trial judge decided that they were not so prejudicial

as to warrant reversal.   Viewing the remarks in context, we agree.

                                    11
They were not “so pronounced and persistent” as to “permeate the

entire atmosphere of the trial.” See Iredia, 866 F.2d at 117

(citing United States v. Williams, 809 F.2d 1072, 1096 (5th Cir.),

rev'd on other grounds, 828 F.2d 1, cert. denied, 484 U.S. 896, 108

S.Ct. 228, 98 L.Ed.2d 187 (1987)).              The AUSA’s focus was not on

Ramirez’s confession as recounted by Agent Perez.                 Rather, she

provided a survey of all the evidence supporting Ramirez’s guilt.

In addition, the court instructed the jury that the lawyers’

arguments were not evidence and that the jurors alone must evaluate

witness credibility.

     Further weighing against reversal of Ramirez’s conviction is

substantial evidence pointing to his guilt.                 The marijuana was

found on the auto transport while it was under Ramirez’s control.

“Knowledge   of    the   presence   of    a    controlled   substance   may   be

inferred from the exercise of control over a vehicle in which the

illegal substance is concealed.”              Diaz-Carreon, 915 F.2d at 954.

In the case of contraband contained in hidden compartments, guilty

knowledge could not properly be inferred from control of the

vehicle alone.     See, e.g., id.        The jury was instructed to decide

whether the drugs were in a hidden compartment, then to decide

whether other evidence supported an inference of knowledge.

     Whatever conclusion the jury reached on the predicate point,

an inference of knowledge from mere control of the transport was

unnecessary.      The only way one could reach the trucks on the top

tier would be to climb up the side of the transport and hold on.

                                     12
A jury contemplating the large, unwieldy duffel bags could infer

that the bags had to be placed in the trucks before the trucks were

perched on the top tier of the transport.           The conclusion that the

bags were   loaded    first     is    especially   reasonable   in   light   of

evidence that marijuana was found also in a truck on the bottom

tier, which Agent McCauley testified was inaccessible while loaded

on the transport.

     Possibly attempting to provide for the opposite inference,

i.e., that the drugs were placed into trucks already loaded on the

transport, Ramirez testified that he loaded four trucks onto the

top tier of the transport, then discovered that the hydraulics were

malfunctioning and called Villarreal. At least with respect to the

trucks on the top tier, this scenario would allow for a window

during which someone could hide the bags in the trucks after

Ramirez inspected and loaded them but before they were raised

beyond   reach.      However,    the     contradiction    between    Ramirez’s

sequencing of events and other evidence only lends greater support

to the inference of guilt.           Soto testified that Ramirez called to

request “liquid” just after he obtained his route assignment, not

after the hour or so it would take to inspect and load four trucks

onto the transport.      The phone records reflect a call from the

phone in the drivers’ room to Villarreal’s cellular phone at 8:07

a.m., just after Ramirez’s arrived at 8:00.              Moreover, Ramirez’s

explanation does not account for the marijuana in the truck on the

bottom tier of the transport.

                                        13
     Other inconsistencies further support the inference of guilt.

Ramirez’s testimony that he received Villarreal’s cellular phone

days before his arrest is incompatible with evidence from phone

records that the call he made from the phone in the drivers’ room

was placed to that cellular phone.         Though Ramirez testified he

called    Villarreal   because   his    transport   needed   maintenance,

Bannerman’s inspection of the transport led him to conclude that no

maintenance had been done.       In contrast to his usual habit of

loading his transport in the loading area, near the security

guards, Ramirez loaded the transport in an area away from the

guards’ post where his transport was obscured by trees.         The jury

reasonably could have inferred that these inconsistencies betray an

agreement that the call for “liquid” was a disguised signal for the

delivery of the marijuana, and that Villarreal’s rare Sunday

morning appearance in a large van with another person was not to

repair the transport but to deliver the marijuana.

     In sum, the record reveals abundant support for the conclusion

that Ramirez knew he was carrying marijuana.        We conclude, viewing

the prosecutor’s remarks in the context of the trial as a whole,

that Ramirez’s substantial rights were not affected.

     2.    Unconstitutionality of § 841(b)

     Ramirez raises the unconstitutionality of 21 U.S.C. § 841(b),

which this Court has interpreted to treat drug type and quantity

not as elements of the crime but as sentencing factors, and asserts

that § 841(b) violates Apprendi v. New Jersey, 530 U.S. 466 (2000).

                                   14
Ramirez acknowledges that we rejected this argument in United

States v. Slaughter, 238 F.3d 580, 582 (5th Cir. 2000), cert.

denied, 532 U.S. 1045 (2001), but wishes to preserve the issue for

further appeals.   We are bound by our precedent on the issue; thus,

we reject Ramirez’s constitutional claim.

B. Villarreal’s claims

      1. Testimony of Agent Perez

      Before trial, the prosecution and counsel for Villarreal

agreed to the admission of Ramirez’s confession so long as any

mention of Villarreal was omitted from the statement and from the

testimony of Agent Perez in connection with the statement.7      In

keeping with this agreement, Agent Perez did not mention Villarreal

during his recounting of Ramirez’s confession.   Despite his waiver

of objection to admission of Ramirez’s confession, Villarreal now


  7
     The following discussion of the agreement took place just
before trial:
MS. SMYTH [for the United States]: One [issue], I believe we have
already reached an agreement on.     It was the statement by co-
defendant Ramirez.    We had talked — I told you in a pre-trial
conference that I wanted to go ahead and discuss that prior to the
beginning of trial, a statement that he made to Border Patrol
agents. I believe we already showed a copy to defense attorney
representing Mr. Villarreal-Lara.
MR. ALMARAZ [counsel for Villarreal]: That is correct, your honor.
THE COURT: Is that agreed, then?
MR. GARCIA [counsel for Ramirez]: Yes, your honor.
MR. ALMARAZ: Yes, my client’s name has been redacted. Any mention
of my co-worker and his name has been redacted. We would just ask
that the prosecutor— to make sure that the agent that testifies
about any statements not mention my client.
THE COURT: Very well.

R.2 91-92

                                 15
objects to admission of the confession, contending first, that it

violated Bruton v. United States, 391 U.S. 123 (1968), and second,

that it was hearsay.

      Having waived his objection to admission of the statement,

Villarreal cannot now argue that its admission was error.              United

States v. Reveles, 190 F.3d 678, 683 (5th Cir. 1999)(quoting United

States v. Olano, 507 U.S. 725, 733, 113 S.Ct. 1770 (1993)).

Likewise, Villarreal’s hearsay objection to Agent Perez’s testimony

fails.      Villarreal’s    waiver   was    unqualified    except    for   the

condition that Agent Perez not mention Villarreal.            Especially in

view of the fact that Villarreal made no hearsay objection to the

testimony    at   trial   and   requested   no   hearsay   instruction,8    we

conclude that Villarreal waived all objections to admission of the

testimony.

      Villareal protests that Agent Perez breached the agreement to

redact his name from the confession.             We disagree.       The first

mention of Villarreal was during redirect examination of Agent

Perez after defense counsel attempted to develop the theory that

Agent Perez learned everything he knew about the case independent

of the disputed confession by Ramirez. The prosecutor sought, here

unsuccessfully, to rebut this theory by eliciting what Agent Perez

learned not from other witnesses but directly from Ramirez:

  8
    Villarreal did request an instruction under Bruton, which the
trial judge declined to issue, reasoning that because Villarreal’s
co-defendant Ramirez testified, Bruton was not implicated.


                                     16
  Q: And when you talked to the defendant [Ramirez] – prior to
  talking to him, you did not know that two people were involved
  as far as driving the van there; is that correct?

  A: I did know because Bannerman had told me that David
  [Villarreal] had showed up. And that’s how I knew that there
  was somebody else in it.9


      Counsel for Villarreal objected that Agent Perez’s answer was

hearsay. The court sustained the objection and instructed the jury

appropriately.   Villarreal now protests that the court’s remedial

action was insufficient to cure the prejudice resulting from Agent

Perez’s inadmissible testimony.

      Villarreal’s contention is meritless.           First, Agent Perez

mentioned Villarreal not in connection with Ramirez’s confession,

but in connection with a statement by John Bannerman.         Therefore,

while the statement was inadmissible hearsay, it was not in breach

of the agreement between the government and Villarreal. Second, to

cure the hearsay testimony, the court instructed the jury to

disregard the question and answer. When the court directs the jury

to disregard evidence determined to be inadmissible, the evidence

will not provide a basis for reversal unless it is “so highly

prejudicial as to be incurable by the trial court’s admonition.”

United States v. Klein, 546 F.2d 1259, 1263 (5th Cir. 1977).         Only

remarks likely to have a substantial impact on the jury’s verdict

warrant reversal. Id.

      Agent   Perez’s   mention   of    Bannerman’s    statement   caused

  9
      2 R. at 17 (emphasis added).

                                   17
Villarreal minimal prejudice, if any.           Soto had already testified

to Villarreal’s arrival in the van.              Moreover, the testimony

actually    advanced   the     defense     assertion     that   Ramirez    never

confessed; Perez was admitting that he had learned of Villarreal’s

presence not from Ramirez but from Bannerman.             No reversible error

occurred in this portion of Agent Perez’s testimony.

       Villarreal   challenges     another     portion     of   Agent     Perez’s

testimony, in which Agent Perez, in response to questioning from

Villarreal’s counsel, stated that Ramirez told him he had received

a cellular phone at the same time he received the marijuana.                 The

testimony makes no mention of Villarreal.10            Counsel for Villarreal

failed to object to Agent Perez’s answer.

       This contention, too, is without merit.           The jury could have

inferred when Ramirez obtained the cellular phone from other

evidence.     Agent    Perez    did   mention    Ramirez’s      confession    in


  10
     Quoted in context, the testimony was as follows:
   Q: Now, you mentioned several phone tolls that you brought and
   mentioned to the jury yesterday. You cannot tell the jury how
   many days Mr. Ramirez had had that cell phone.
   A: Yes sir, I can.
   Q: Okay. You have no idea what person was using that phone
   during those calls.
   A: Yes, sir, I can.
   Q: You were there when the calls were being made?
   A: No, but based on what Fredi [Ramirez] told me. He told me
   that he had received the phone at the same time he had
   received the marijuana.
   Q: You have no idea of the conversation that took place on all
   of those calls?
   A: I do on one of them, yes sir.
   Q: Okay.
R.2 at 4.

                                      18
answering these questions, but he avoided mentioning Villarreal’s

name and the fact that the phone belonged to Villarreal.                       Thus,

Villarreal is bound to his waiver.

       2. Testimony of Agent Shawn Hacking

       Villarreal argues that the government’s expert witness, DEA

Agent Shawn Hacking, testified regarding Ramirez’s mental state,

which under Federal Rule of Evidence 704(b) is outside the purview

of expert testimony.         The prosecutor at first sought an explicit

opinion, asking, “And based on your experience, do those drivers

know what they are carrying?”11 On defense counsel’s objection, the

prosecutor rephrased her question in terms of how drug conspiracy

organizations       choose   their   drivers.       Agent       Hacking,    with    no

objection from defense counsel, testified that drivers are paid

based on past performance, and that organizations tend to seek

trustworthy      drivers     because     their     cargo    is      valuable       and

uninsurable.12

       Because   Villarreal     failed      to   object    to    Agent     Hacking’s

testimony, our review is confined to that for plain error.                     Plain


  11
       R.2 at 63.
  12
     Agent Hacking testified:
   With a legitimate product you have–- you don’t have to conceal
   it. And you have insurance in case the product is lost or
   damaged. In the case of an illegal product, of course you
   have to conceal it and try to get it where it’s going without
   being detected. There is no insurance if it’s lost or stolen.
   The only real assurance you have is the trust you have in the
   people that are working for you.
R.2 at63-64.

                                       19
error requires that there be (1) error; (2) that is plain, which

“at a minimum,” means “the error is clear under current law,” and

(3) that affects the substantial rights of the defendant. Olano,

507 U.S. at 733-34, 113 S.Ct. at 1777-78.            Whether to correct

forfeited plain error is within the discretion of the reviewing

court. Id. at 735, 113 S. Ct. at 1778.              The exercise of our

discretion is appropriate only when the error "’seriously affect[s]

the    fairness,    integrity   or   public     reputation     of    judicial

proceedings.’" Id. at 736, 113 S. Ct. at 1779 (quoting United

States v. Atkinson, 297 U.S. 157, 160, 56 S.Ct. 391, 392, 80 L.Ed.

555 (1936)).

       This Court has held that “narcotics agent[s] may testify about

the significance of certain conduct or methods of operation unique

to the drug business so long as the testimony is helpful and its

relevance is not substantially outweighed by the possibility of

unfair prejudice or confusion.”       United States v. Garcia, 86 F.3d

394,   400   (5th   Cir.   1996).    The   government   goes   too    far   in

soliciting the functional equivalent of an opinion whether the

defendant knew he was carrying drugs.         United States v. Gutierrez-

Farias, 294 F.3d 657, 663-64 (5th Cir. 2002).

       The testimony we held to be improper in Gutierrez-Farias bears

great similarity to that offered by Agent Hacking.13            As did the

  13
     In Gutierrez-Farias, Agent Afanasewicz described the manner in
which people are chosen to transport drug[s]:
   The way it usually works in that respect is that I don't think
   they would target somebody just off the street that, you know,

                                     20
agent in Gutierrez-Farias, Agent Hacking made the generalization,

albeit not quite directly, that drivers know they are carrying

drugs.     Thus we are presented with a violation, plain under

Gutierrez-Farias, of Federal Rule of Evidence 704(b).                    Villarreal

has the    burden    of   demonstrating     that    the    error    affected     his

substantial rights, i.e., affected the outcome of the proceedings.

Olano, 507 U.S. at 734.         He has not met this burden.

     Agent Hacking’s testimony was relevant to the mental state of

the driver, Ramirez; it was not relevant to Villarreal’s mental

state.    Additionally, the court instructed the jury both before

Agent    Hacking    testified    and   again   at   the    end    of     the   trial,

explaining that (a) Agent Hacking was not claiming to know the

particular facts of the case and (b) his testimony was to be

weighed and could be disregarded like that of any other witness.

Considering    these      factors   together   with       the    other    evidence,

discussed below, from which the jury could infer Villarreal’s

guilt, we conclude that admission of Agent Hacking’s testimony did


  has no knowledge. Usually, it's somebody that is a friend of
  a friend. It could start that way.
  Usually they want to use people that are--that can be--have a
  certain amount of trust and responsibility because you have to
  realize as we showed before here, the amount of money that the
  narcotics communicates too. It's a lot of money and, you know,
  this is, like I said, a business. So I mean, just as in any
  other business, the people need a certain amount of
  credentials, if you will, to be employed or to be sought out
  by a narcotics trafficking organization.

  Gutierrez-Farias, 294 F.3d at 662.



                                       21
not affect Villarreal’s substantial rights.

3. Sufficiency of the Evidence

     Villarreal    challenges     the    sufficiency        of    the       evidence

supporting his convictions.       We view the evidence “in the light

most favorable to the verdict to determine whether a rational jury

could have found the elements of the offense beyond a reasonable

doubt.”     Gutierrez-Farias,     294    F.3d   at   660.        We    accept   all

credibility choices tending to support the verdict.                   Id.

     The conviction for possession of more than 100 kilograms of

marijuana with intent to distribute requires the government to

establish   the   defendant’s     "1)    knowing;      2)   possession        of   a

controlled substance; 3) with the intent to distribute it."                     Id.

Possession may be constructive; “constructive possession is ‘the

knowing exercise of, or the knowing power or right to exercise,

dominion and control over the proscribed substance.’”                         United

States v.   Brito,   136   F.3d   397,    409   (5th    Cir.     1998)(citation

omitted).   To establish aiding and abetting under 18 U.S.C. § 2,

the government must show that the defendant (1) associated with a

criminal venture, (2) participated in the venture, and (3) sought

by action to make the venture successful.                   United States v.

Carreon-Palacio, 267 F.3d 381 (5th. Cir 2001).

     To sustain a verdict for conspiracy, the government must

establish: "1) the existence of an agreement between two or more

persons; 2) the defendant's knowledge of the agreement; and 3) the

defendant's voluntary participation in the conspiracy." United

                                    22
States v. Brown, 29 F.3d 953, 958 (5th Cir.), cert. denied, 513

U.S. 1021, 115 S.Ct. 587, 130 L.Ed.2d 501 (1994). No proof of an

overt act is required to establish a violation of 21 U.S.C. § 846.

United States v. Shabani, 513 U.S. 10, 17, 115 S.Ct. 382, 386

(1994).       Each   element   of    a   conspiracy     may   be    inferred      from

circumstantial evidence. United States v. Faulkner, 17 F.3d 745,

768 (5th Cir. 1994), and “may be inferred from the development and

collocation of circumstances.” United States v. Mendoza, 226 F.3d

340, 343 (5th Cir. 2000).           The government must, however, do more

than simply "pile inference upon inference upon which to base a

conspiracy charge." United States v. Williams-Hendricks, 805 F.2d

496, 502 (5th Cir.1986).              The government cannot “prove up a

conspiracy merely by presenting evidence placing the defendant in

a climate of activity that reeks of something foul." United States

v. Maltos, 985 F.2d 743, 746 (5th Cir. 1992).

       Although the jury acquitted Ramirez of conspiracy, we conclude

that    the   evidence     supports      beyond    a   reasonable        doubt    that

Villarreal     conspired    with     Ramirez      to   possess     more    than   100

kilograms of marijuana with the intent to distribute it.                           See

United States v. Zuniga-Salinas, 952 F.2d 876 (5th Cir. 1992)

(coconspirator’s acquittal does not bar defendant’s conviction for

conspiracy—apparent      inconsistency        could    indicate     no    more    than

leniency, mistake, or compromise by the jury).

       Ramirez obtained his dispatch sheet, with the list of trucks

to be taken, when he arrived to work that morning.                 The jury could

                                         23
reasonably infer that Ramirez did not know until then which trucks

he would receive, and that the marijuana was not loaded into the

trucks until after he received them.                       Ramirez’s 8:07 a.m. call,

made    before      Ramirez    would       have      had     time    to     discover       the

malfunctioning         hydraulics         to     which      he     testified,       brought

Villarreal, who rarely worked on weekends, to Kaizen that early

Sunday morning in a large van driven by an unknown person.                                From

these facts the jury could infer that the call was an agreed-upon

signal for Villarreal to deliver the marijuana.

       The   van,     which   arrived      just      as    Ramirez    was       loading    his

transport, did not stop to check in with the security guards;

rather, it       proceeded     directly         to   the    area    where       Ramirez    was

loading—out      of    view   of    the    security        guards.        The    reasonable

inference is that Villarreal wanted to avoid the guards for fear

that they might inspect the van and discover its cargo.                                   The

limited accessibility of the trucks while loaded on the transport,

taken together with the size of the duffel bags, allows for the

inference that the bags were placed inside the trucks before the

trucks were loaded on the transport.                       Villarreal’s arrival that

morning coincides with the opportunity to load the bags into the

trucks while they were still on the ground.

       Villarreal, before leaving in the van, told Soto that he had

repaired a flat tire.         Ramirez testified that Villarreal had added

hydraulic     fluid     to    the    transport.              Both    explanations          for

Villarreal’s presence were rebutted by Bannerman’s testimony that

                                               24
inspection of the transport revealed no evidence of a flat tire or

a broken hydraulic line.       It is reasonable to conclude that the men

both lied     about   maintenance     being    done   on    the   truck   because

Villarreal was there not to perform maintenance, but to deliver the

marijuana.

      Ramirez      testified   that    he    had   been     in    possession    of

Villarreal’s cellular phone for several days, and that he had used

the   phone   to   call   Villarreal    in    to   work    that   morning.     This

explanation is contradicted by phone records reflecting the 8:07

call from the drivers’ room to Villarreal’s cellular phone just

before Villarreal’s arrival at Kaizen.             From this the jury could

infer that Villarreal was in possession of the cellular phone

before his arrival at Kaizen. Ramirez’s possession of Villarreal’s

cellular phone at the time of his arrest supports the inference

that Villarreal gave him the cellular phone when the two saw each

other that morning.       The reasonable inference that Villarreal was

expecting to monitor Ramirez’s progress is further supported by the

eight calls from Villarreal’s Kaizen cellular phone to his personal

cellular phone that afternoon.

      Viewing this aggregation of circumstances in a light favoring

the verdict, we conclude that the evidence is sufficient to support

Villarreal’s convictions.

CONCLUSION

      We have reviewed all of the errors asserted by Ramirez and

Villarreal and determine that none warrant reversal of their

                                       25
convictions.   We therefore affirm the judgment of the district

court.



AFFIRMED.




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