STAHL, Circuit Judge.

Defendants-appellants Wanda Diaz-Perez and Vanessa de la Cruz-Paulino (collectively, "defendants") appeal their convictions for aiding and abetting each other and others in the unlawful possession of, with intent to distribute, approximately eighty kilograms of cocaine, in violation of 21 U.S.C. § 841(a)(1) and 18 U.S.C. § 2. Diaz-Perez also appeals her conviction for using a communications facility on six separate occasions to facilitate the distribution of cocaine, in violation of 21 U.S.C. § 843(b). Diaz-Perez argues that she is entitled to a new trial because the government violated Fed.R.Crim.P. 12(d)(2) by failing to designate certain of the evidence it intended to use during its case in chief; because the district court admitted hearsay tape recordings into evidence; and because the trial judge made prejudicial comments in front of the jury. Both Diaz-Perez and de la Cruz-Paulino argue that the district court abused its discretion in allowing a representative sample of cocaine to be sent into the jury deliberation room. Finally, de la Cruz-Paulino argues that the evidence was insufficient to establish her guilt beyond a reasonable doubt. We affirm Diaz-Perez's conviction, but reverse de la Cruz-Paulino's conviction for insufficient evidence.

I. Background

On January 21, 1994, Federal Drug Enforcement Administration ("DEA") agents in Puerto Rico met with a cooperating individual known as "Chita," who spoke with them about a pending drug transaction involving 200 kilograms of cocaine. Chita told the agents that the Puerto Rican contact was known as "Negro." He did not refer to either defendant.

Between 12:00 noon and 4:20 p.m., DEA agents recorded four telephone conversations placed by Chita to a Colombian contact known as "Jota." During the trial, the district court admitted tapes of these recorded conversations into evidence without objection from defense counsel. In one of the conversations, Jota told Chita that he would make arrangements for the Puerto Rican contact, whom he referred to as a female schoolteacher, to telephone Chita at the number Chita provided, which in reality was the number for a DEA cellular telephone. It was established at trial that Diaz-Perez was a teacher.

Not long after these telephone calls ended, the DEA decided to abort the operation, and Agents Andaluz and Salazar transported Chita to the airport. While en route to the airport, however, the agents received a call from Diaz-Perez on the DEA telephone. The ensuing conversation was not recorded. However, at trial, Diaz-Perez testified that during that unrecorded conversation, she was told that the wrapped packages she was transporting contained coffee for which excise taxes had not been paid and was instructed not to mention any names during subsequent conversations. Andaluz testified that he was the one who had spoken with Diaz-Perez during the unrecorded conversation and that he never mentioned the word "coffee."

After dropping Chita off at the airport, Andaluz and Salazar returned to DEA headquarters and conferred with other agents regarding the contents of the call. They then decided to contact Diaz-Perez and arrange for a transfer of the cocaine. To accomplish this, Andaluz placed five telephone calls to Diaz-Perez between 7:10 p.m. and 9:55 p.m. and received one telephone call from Diaz-Perez. The DEA recorded all of these conversations, and the district court admitted the recordings into evidence, Diaz-Perez stipulating that the voice in the recordings belonged to her. None of the conversants explicitly referred to cocaine or coffee in the recorded conversations, although Andaluz did use the word "kilos" once.

During the six recorded conversations, Andaluz and Diaz-Perez discussed the details of the delivery, including the mode of transportation and the size of the shipment. After a brief exchange in which Diaz-Perez attempted to solicit Andaluz's help in carrying the bags containing the cocaine down from a second-story apartment, Andaluz asked, "Can't you give somebody there $30, $40 I'll pay you back over here, to place it in the trunk, only to place it in the trunk, don't bring him over or anything, to come over here?" Diaz-Perez indicated that she would, and eventually Andaluz and Diaz-Perez agreed to meet in the parking lot of a Burger King restaurant.

At trial, Andaluz testified that after Diaz-Perez and de la Cruz-Paulino arrived at the Burger King parking lot, but before he and Salazar approached them, he activated a concealed microcassette recorder. The district court admitted the recording of the subsequent conversation into evidence without objection. After greeting defendants, Salazar asked, "Did you get it down," and de la Cruz-Paulino answered, "Of course we did." A short discussion about the $40 followed, after which Andaluz asked Diaz-Perez, "Which is your car?" Diaz-Perez stated, "That black one there, in the trunk, two bales and . . . eight doubles. . . ." Andaluz and Salazar opened the trunk and one of the garbage bags, Andaluz stating that he had "[t]o check it out girl, because what will I do with [unintelligible]." Diaz-Perez then exclaimed, "Shut up! Oh, God, the two bales and the other stuff." Andaluz then said, "No, relax, we are getting involved here to get a party." De la Cruz-Paulino then said, "No, watch out the police is around, going around here." Defendants were arrested immediately thereafter.

DEA agents searched Diaz-Perez's car at the time of defendants' arrest. The trunk contained approximately eighty kilograms of cocaine with a stipulated value of $1.2 million. The cocaine was wrapped and sealed in such a way that it was impossible to see the contents. Also seized were a cellular telephone, a package of coffee, and a piece of cardboard. Chita's name was written on the cardboard, along with the DEA telephone number, several figures that totaled eighty, and the words "coffee" and "large garbage bags." DEA agents did not find any weapons, nor did they test defendants' clothing for the presence of cocaine.

Defendants were subsequently indicted for aiding and abetting each other and others in possession of, with intent to distribute, a controlled substance, in violation of 21 U.S.C. § 841(a)(1) and 18 U.S.C. § 2. Diaz-Perez was also indicted on six counts of using a communications facility in furtherance of a narcotics transaction, in violation of 21 U.S.C. § 843(b).

Prior to trial, defendants requested, pursuant to Fed.R.Crim.P. 12(d)(2), that the government designate the evidence it intended to introduce at trial. In response, the government designated the seized cocaine, the materials in which the cocaine had been wrapped, and various tape recordings and photographs. In addition, the government stated, "Any other physical and/or documentary evidence will be notified at least five (5) days before the date of trial." The government never notified defendants that it intended to introduce the telephone or the cardboard seized from Diaz-Perez's car into evidence. Nonetheless, the government referred to both pieces of evidence during its opening statement at defendants' jury trial.

Immediately following the opening statement of Diaz-Perez, both defense counsel moved to exclude the telephone and the cardboard because they had not been designated as evidence by the government as required under Rule 12(d)(2). During the discussion on defendants' motion, the government never admitted that it had not designated either piece of evidence, but instead repeatedly insisted that it had provided defendants with full discovery, stating, for example,

they were fully aware that this was a piece of evidence and this is not [a] surprise to them they had it from about three weeks after the defendants had been arrested this is no surprise to them, they should be aware that this was a piece of evidence and the government could attempt to use such evidence.

The district court denied the motion, stating, "it's been provided." When defense counsel objected that the evidence, although provided under Fed.R.Crim.P. 16, had not been designated as required by Rule 12(d)(2), the district court stated, "It is not [a] surprise, it[']s there and you have it." The evidence was subsequently admitted without further objection.

At the close of the government's case in chief, both defendants moved pursuant to Fed.R.Crim.P. 29 for judgments of acquittal; the district court denied both motions. Diaz-Perez then testified in her own defense, but offered no other evidence. De la Cruz Paulino did not testify and offered no evidence. At the close of trial, both defendants renewed their Rule 29 motions, and each defendant also objected to the district court's decision to allow a representative sample of unpackaged cocaine, which had been admitted into evidence without objection, into the jury room. Defendants now appeal their convictions.

II. Discussion

A. Rule 12(d)(2) Violation

Diaz-Perez argues that the district court abused its discretion in admitting into evidence the cellular telephone and the piece of cardboard because the government did not disclose its intent to use the evidence during its case in chief as required by Fed.R.Crim.P. 12(d)(2). Diaz-Perez first argues that the district court erred in holding that the government did not violate Rule 12(d)(2) since it had provided defendants with open-file discovery. We agree. "To the extent that the government's open files contain information that is subject to Rule 16 discovery, Rule 12(d)(2) creates a notice requirement. The open file policy does not, in and of itself, satisfy this notice requirement because it does not specify which evidence the government intends to use at trial." United States v. Brock, 863 F. Supp. 851, 868 (E.D.Wis. 1994). Providing open-file discovery does not satisfy Rule 12(d)(2) because "the defendant is still 'left in the dark' as to exactly what evidence, discoverable under Rule 16, the government intends to rely upon in its case in chief at trial." United States v. Kelley, 120 F.R.D. 103, 107 (E.D.Wis. 1988). Thus the district court erred in ruling that the government's open-file discovery satisfied the requirement of Rule 12(d)(2). The government's failure to designate either the telephone or the cardboard as evidence was a violation of the rule.

Diaz-Perez next argues that to remedy the government's Rule 12(d)(2) violation, we should reverse her conviction and remand for a new trial as we did for the victim of a Rule 16 violation in United States v. Alvarez, 987 F.2d 77, 85-86 (1st Cir.), cert. denied, ___ U.S. ___, 114 S.Ct. 147, 126 L.Ed.2d 109 (1993). We do not agree.

We have not yet addressed the effect of a violation of Rule 12(d)(2). In reviewing discovery violations, however, we have made clear that "[a] defendant must prove that the alleged violation prejudiced his case to succeed in obtaining a reversal on appeal." United States v. Nickens, 955 F.2d 112, 126 (1st Cir.), cert. denied, ___ U.S. ___, 113 S.Ct. 108, 121 L.Ed.2d 66 (1992); see also United States v. Valencia, 656 F.2d 412, 416 (9th Cir.), cert. denied, 454 U.S. 877, 903, 102 S.Ct. 356, 411, 70 L.Ed.2d 186, 222 (1981). We extend this prejudice requirement to violations of Rule 12(d)(2).

Diaz-Perez argues that the government's Rule 12(d)(2) violation prejudiced her in three ways: (1) she was not prepared to file a motion to suppress the evidence, (2) the evidence forced her to alter her trial strategy, and (3) the evidence had an effect on her plea strategy. None of these reasons warrants reversal in this case.

Rule 12(d) is "a matter of procedure, "Fed.R.Crim.P. 12 advisory committee's note (internal quotation omitted), rather than a rule designed to ensure fairness at trial. As its text makes clear, Rule 12(d)(2) allows defendants to request notice of the government's intent to use evidence " in order to afford an opportunity to move to suppress evidence under subdivision (b)(3) of this rule." Fed.R.Crim.P. 12(d)(2) (emphasis added). Rule 12(d) "provides a mechanism for insuring that a defendant knows of the government's intention to use evidence to which the defendant may want to object" so that the defendant may "avoid the necessity of moving to suppress evidence which the government does not intend to use." Fed.R.Crim.P. 12 advisory committee's note; see also 1 Charles A. Wright, Federal Practice and Procedure: Criminal § 197, at 735 (2d ed. 1982) (Rule 12(d) "is intended to facilitate the making of a pretrial motion for suppression of evidence."). Thus, Rule 12(d) aids defendants in complying with their Rule 12(b)(3) obligation to make motions to suppress evidence prior to trial. This in turn preserves the integrity of a trial by not interrupting it with suppression motions. See Fed.R.Crim.P. 12 advisory committee's note (Rule 12(b)(3) "'is designed to eliminate from the trial disputes over police conduct not immediately relevant to the question of guilt'") (quoting Jones v. United States, 362 U.S. 257, 264, 80 S.Ct. 725, 732, 4 L.Ed.2d 697 (1960) (emphasis eliminated)).

As "a matter of procedure," Rule 12(d) differs from discovery rules designed to ensure fairness. See Fed.R.Crim.P. 12(d) advisory committee's note; cf. Fed.R.Crim.P. 12.1 (Notice of Alibi) advisory committee's note ("[t]he major purpose of a notice-of-alibi rule is to prevent unfair surprise"); Fed.R.Crim.P. 16 (Discovery and Inspection) advisory committee's note ("broad discovery contributes to the fair and efficient administration of criminal justice by providing the defendant with enough information to make an informed decision as to plea; by minimizing the undesirable effect of surprise at the trial; and by otherwise contributing to an accurate determination of the issue of guilt or innocence"). Rule 12(d) was not designed to aid the defendant in ascertaining the government's trial strategy, but only in effectively bringing suppression motions before trial, as required by Rule 12(b)(3).

We first consider Diaz-Perez's argument that she was prejudiced because, not expecting the government to introduce the telephone or the cardboard, she was unprepared to file a motion to suppress either of them. On appeal, Diaz-Perez does not articulate any basis for suppression of the evidence; we note that Diaz-Perez did not seek to suppress other evidence seized from her car, nor does there appear to us to be a basis for suppressing the evidence. Absent some discussion regarding suppression, we will not view the lack of opportunity for a suppression hearing as prejudicial. Merely stating that "the decision to file a motion to suppress . . . could have been significantly affected by the knowledge prior to trial that the government intended to present those items in evidence" is not enough.

Diaz-Perez also argues that the admission of the telephone and the cardboard greatly affected her trial strategy and her incentives to plead guilty since the government's case became markedly stronger with that evidence. Rule 12(d) was not, however, designed to alert defendants to the strength or weakness of the government's case against them; rather, it was designed to aid defendants in fulfilling their Rule 12(b)(3) obligation to make suppression motions prior to trial. Since trial strategy and plea strategy are simply not implicated by Rule 12(d), the alleged effect of a Rule 12(d) violation upon trial strategy or plea strategy cannot satisfy the prejudice requirements for reversal on appeal.

We recognize, however, that even though Rule 12(d) was not designed to give defendants notice of the government's trial strategy, the government's failure to designate certain pieces of evidence could work an unfairness if the defendant were not prepared immediately to rebut it. In such cases, we think that a district court would not abuse its discretion by granting the defendant a continuance, rather than allowing the government effectively to sandbag the defendant by introducing previously undesignated evidence. Whether or not a defendant should be granted a continuance for fairness reasons, however, is a matter best left to the discretion of the district court. On appeal, we will only consider prejudice stemming from the function of Rule 12(d), namely matters regarding potential motions to suppress.

Thus, although the government violated Rule 12(d)(2) by not indicating prior to trial its intention to introduce the telephone and the cardboard into evidence during its case in chief, reversal is not mandated because Diaz-Perez suffered no prejudice. That having been said, we pause to make clear that we do not condone governmental violations of this sort. Like the Advisory Committee, however, we believe that in general, "attorneys for the government will in fact comply [with Rule 12(d)(2)]." Fed.R.Crim.P. 12 advisory committee's note. We rely on district courts to impose appropriate sanctions for governmental noncompliance and encourage them to grant continuances and hold additional suppression hearings where warranted. Cf. Valencia, 656 F.2d at 416 (finding no error in admission of undesignated evidence where the district court conducted a second suppression hearing to determine admissibility of undesignated evidence). Where governmental noncompliance is the result of bad faith, exclusion of the undesignated evidence may be appropriate. Cf. United States v. Flores-Rivera, 56 F.3d 319, 328 n. 7 (1st Cir. 1995) (repeating admonishment against government misconduct and stating that court may use supervisory power to dismiss an indictment to deter future prosecutorial misconduct).

B. Tape Recordings

Diaz-Perez next argues that the district court committed reversible error by admitting into evidence three tape recordings of conversations between Chita and two unnamed and uncharged Colombian contacts. Diaz-Perez believes that the contents of the tape recordings constitute hearsay subject to no exception. Diaz-Perez argues that the tapes could not have been (implicitly) admitted pursuant to Fed.R.Evid. 801(d)(2)(E) since the district court made no factual finding that the persons on the tapes were participating in a conspiracy with Diaz-Perez and speaking in furtherance of that conspiracy as required by United States v. Petrozziello, 548 F.2d 20, 23 (1st Cir. 1977). In addition, Diaz-Perez contends that had an inquiry been conducted, the court could not have found that "the declarant and the defendant were members of a conspiracy when the hearsay statement was made, and that the statement was in furtherance of the conspiracy." Id. at 23.

Because Diaz-Perez failed to object in the district court, the issue has not been preserved for appeal. As we explained in United States v. Figueroa, 818 F.2d 1020, 1026 (1st Cir. 1987) (alteration in Figueroa):

[T]he Petrozziello rule is designed to protect the integrity of the trial in borderline situations where the prosecution may or may not be able to muster sufficient proof of the existence, scope, shape, and duration of an alleged conspiracy. If the defendant elects not to put the government to this test — either for tactical reasons or because the outcome, realistically, is foreordained — he is in a poor position to complain after the fact. As we stated in United States v. David E. Thompson, Inc., 621 F.2d 1147, 1153 (1st Cir. 1980), "[i]n the absence of a proper objection, Fed.R.Evid. 103(a)(1), a deviation from the standard announced in Petrozziello will be reversed only upon a showing of plain error."

The "plain error" standard requires the reviewing court to ask: (1) whether there is an error; (2) whether the error is "plain," a term synonymous with "clear" or "obvious"; and (3) whether the error affected substantial rights. United States v. Olano, ___ U.S. ___, ___-___, 113 S.Ct. 1770, 1777-1778, 123 L.Ed.2d 508 (1993); see also Fed.R.Crim.P. 52(b) ("Plain errors or defects affecting substantial rights may be noticed although they were not brought to the attention of the court."). An "error rises to this level only when it is so shocking that it seriously affected the fundamental fairness and basic integrity of the proceedings conducted below." United States v. Ortiz, 23 F.3d 21, 26 (1st Cir. 1994) (internal quotations omitted).

Applying the plain-error standard, we reject Diaz-Perez's argument. Even assuming arguendo that Diaz-Perez was not involved in a conspiracy with the persons on the tapes and, therefore, that the judge could not have made the required findings under Petrozziello, we do not believe that the error passes the "clear" or "obvious" hurdle. "Where the error defendant asserts on appeal depends upon a factual finding the defendant neglected to ask the district court to make, the error cannot be 'clear' or 'obvious' unless the desired factual finding is the only one rationally supported by the record below." United States v. Olivier-Diaz, 13 F.3d 1, 5 (1st Cir. 1993) (emphasis added). In this case, Diaz-Perez's "desired" factual finding is that she was not involved in a conspiracy with the Chita's Colombian contacts. We do not believe, however, that such a finding is the "only one rationally supported by the record below." Rather, the non-hearsay evidence presented at trial makes it plausible that Diaz-Perez was involved in a conspiracy to distribute cocaine. In fact, Count One of the Indictment charged both defendants with "aiding and abetting each other, and others to this Grand Jury unknown." Additionally, while the tape recordings between Chita and his Colombian contacts do not mention Diaz-Perez by name, the Colombian contacts did indicate that the informant would be contacted by a female schoolteacher in Puerto Rico. See United States v. Ortiz, 966 F.2d 707, 716 (1st Cir. 1992) (holding that there was no plain error in district court's failure to make an unrequested Petrozziello finding because enough evidence existed to support a finding, based on a preponderance of the evidence, that the codefendants were participating in a conspiracy at the time the statements were made), cert. denied, ___ U.S. ___, 113 S.Ct. 1005, 122 L.Ed.2d 154 (1993).

Accordingly, because Diaz-Perez failed to produce any evidence at trial to deny her role in a conspiracy, we cannot conclude that the district court committed obvious error in allowing the tapes into evidence. Therefore, because the alleged error is not clear or obvious, we need not reach the other elements of the plain-error review.

C. Judicial Bias

Diaz-Perez also complains that throughout the trial, the district court "overstepp[ed] its bounds and assum[ed] the role of an advocate for the prosecution" and "constantly interjected in a manner that indicated annoyance and bias against [defense] counsel," thus preventing Diaz-Perez from having a fair trial.

"It cannot be gainsaid that '[a] fair trial in a fair tribunal is a basic requirement of due process.'" United States v. Nueva, 979 F.2d 880, 885 (1st Cir. 1992) (quoting In re Murchison, 349 U.S. 133, 136, 75 S.Ct. 623, 625, 99 L.Ed. 942 (1955)) (alteration in Nueva), cert. denied, ___ U.S. ___, 113 S.Ct. 1615, 123 L.Ed.2d 175 (1993). Accordingly, a trial judge should be fair and impartial in his or her comments during a jury trial. United States v. Twomey, 806 F.2d 1136, 1140 (1st Cir. 1986). However, "a finding of partiality should be reached only 'from an abiding impression left from a reading of the entire record.'" Id. (quoting Offutt v. United States, 348 U.S. 11, 12, 75 S.Ct. 11, 12, 99 L.Ed. 11 (1954)). After scrutinizing the entire record with care, we are left with no such abiding impression.

D. Cocaine in the Jury Room

Both defendants argue that the district court abused its discretion when it permitted an unwrapped sample of cocaine to be sent into the jury room during deliberations. The unwrapped cocaine had been offered into evidence by the government, without objection, as part of a representative sample of the cocaine that had been seized at the time of defendants' arrest. Immediately after the jury charge, however, defense counsel did object to the unwrapped cocaine being sent into the jury room on the grounds that the evidence was confusing, unnecessary, and inflammatory. We are not persuaded.

We review a district court's decision to send evidence into the jury room for abuse of discretion. United States v. McCarthy, 961 F.2d 972, 978 (1st Cir. 1992) ("Whether evidentiary exhibits properly admitted should or should not accompany the jury to the jury room is a discretionary matter for the trial court.") (internal quotations omitted); United States v. Rawwad, 807 F.2d 294, 297 (1st Cir. 1986) (reviewing the district court's decision to send more than fifteen pounds of heroin into the jury room for abuse of discretion), cert. denied, 482 U.S. 909, 107 S.Ct. 2490, 96 L.Ed.2d 382 (1987). District courts have discretion to allow properly admitted evidence to accompany the jury into the jury room. Rawwad, 807 F.2d at 297. This is true even when the evidence is drugs, for the presence of drugs in the jury room is not per se prejudicial or inflammatory. Id.

Defendants argue that even if it would generally be within a district court's discretion to allow drugs to be sent into the jury room, the district court nonetheless abused its discretion in this case because defendants' knowledge of what was in the wrapped packages was at issue. In particular, defendants contend that the jurors "would [have been] instantly struck by the clear plastic bags of a white powdery substance" during their deliberations and would have been confused. We do not agree. In reviewing the record, we find no reason why the presence of the unwrapped cocaine sample in the jury room would have been particularly inflammatory or prejudicial to defendants. During trial, there was substantial, uncontroverted testimony that the cocaine was wrapped in such a way that it would not have been possible for anyone to see through the packaging. Additionally, during the charge, the court instructed the jurors that the government had stipulated that no one could "see from the outside what was in the wrapped bags," and that defendants' pleas of not guilty put all the essential elements of the charged offense at issue, including knowledge and intent. Finally, in addition to the unwrapped cocaine, other items of evidence were also sent into the jury room, including samples of the packaging material and kilograms of cocaine in their original wrapping.

E. Sufficiency of the Evidence as to de la Cruz-Paulino

At the close of the government's case in chief, de la Cruz-Paulino moved, pursuant to Fed.R.Crim.P. 29, for a judgment of acquittal, contending that the government had not presented sufficient evidence to sustain a conviction. After the district court denied the motion, de la Cruz-Paulino presented no evidence in her own defense. Accordingly, unlike defendants who do present evidence, de la Cruz Paulino did not waive review of the district court's initial Rule 29 decision. United States v. Clotida, 892 F.2d 1098, 1100 (1st Cir. 1989); 2 Charles A. Wright, Federal Practice and Procedure: Criminal § 463, at 642 (2d ed. 1982). This is so even though de la Cruz-Paulino's codefendant did mount a defense by testifying in her own behalf. See Clotida, 892 F.2d at 1103. Thus, on appeal we must determine whether, "when examined in a light most favorable to the government, the evidence presented in the government's case-in-chief, including all inferences that may be drawn therefrom, would permit a reasonable juror to find guilt beyond a reasonable doubt." Id. Even though Diaz-Perez's testimony might have influenced the jury in its decision to convict de la Cruz-Paulino, we may not consider that testimony on appeal. See id.; cf. McGautha v. California, 402 U.S. 183, 215, 91 S.Ct. 1454, 1471, 28 L.Ed.2d 711 (1971) ("a defendant whose motion for acquittal at the close of the Government's case is denied must decide whether to stand on his motion or put on a defense, with the risk that in doing so he will bolster the Government case enough for it to support a verdict of guilty"); 2 Wright, Federal Practice and Procedure: Criminal § 463, at 645 (if the defendant presents evidence after the denial of his or her Rule 29 motion, "[t]he conviction will be affirmed, even though the prosecution may have failed to make a prima facie case, if the evidence for the defense supplied the defect, and the whole record is sufficient to sustain a conviction").

Taken in the light most favorable to the government, the evidence presented during the government's case in chief established the following: (1) de la Cruz-Paulino helped move garbage bags containing sealed packages of cocaine into Diaz-Perez's car; (2) de la Cruz-Paulino was in the car while Diaz-Perez spoke with Agent Andaluz on her cellular telephone; (3) de la Cruz-Paulino was present at the Burger King delivery scene; and (4) after Agents Andaluz and Salazar opened one of the garbage bags, de la Cruz-Paulino stated, "No, watch out the police is around, going around here." de la Cruz-Paulino argues that because this evidence is insufficient to allow a jury to conclude beyond a reasonable doubt that she aided and abetted Diaz-Perez and others in the possession of cocaine with intent to distribute, the district court should have granted her Rule 29 motion for judgment of acquittal at the close of the government's case in chief. We agree.

To be convicted of aiding and abetting, more than "mere presence" at the scene is required. United States v. Mehtala, 578 F.2d 6, 9 (1st Cir. 1978). The classic definition of aiding and abetting, adopted by the Supreme Court, was first enunciated by Learned Hand:

In order to aid and abet another to commit a crime it is necessary that a defendant "in some sort associate himself with the venture, that he participate in it as something that he wishes to bring about, that he seek by his action to make it succeed."

Nye Nissen v. United States, 336 U.S. 613, 619, 69 S.Ct. 766, 769-70, 93 L.Ed. 919 (1949) (quoting United States v. Peoni, 100 F.2d 401, 402 (2d Cir. 1938) (L. Hand, J.)). Thus, for de la Cruz-Paulino to have been convicted under an aiding-and-abetting theory, the government had to prove (1) that Diaz-Perez committed the underlying substantive crime and (2) that de la Cruz-Paulino shared Diaz-Perez's criminal intent. See United States v. Valerio, 48 F.3d 58, 64 (1st Cir. 1995). The government fulfilled the first prong, for Diaz-Perez was convicted. To fulfill the second prong, the government had to prove that de la Cruz-Paulino "consciously shared [Diaz-Perez's] knowledge of the underlying criminal act, and intended to help [her]," United States v. Taylor, 54 F.3d 967, 975 (1st Cir. 1995); see also United States v. Loder, 23 F.3d 586, 591 (1st Cir. 1994) (discussing specific-intent requirement for aiding and abetting). This the government did not do.

"[T]he line that separates mere presence from culpable presence is a thin one, often difficult to plot." Ortiz, 966 F.2d at 712. On the one hand, "[m]ere association between the principal and those accused of aiding and abetting is not sufficient to establish guilt; nor is mere presence at the scene and knowledge that a crime was to be committed sufficient to establish aiding and abetting." Mehtala, 578 F.2d at 10 (internal quotation omitted); see also United States v. Campa, 679 F.2d 1006, 1010 (1st Cir. 1982) ("Mere presence at the scene and knowledge that a crime is being committed is generally insufficient to establish aiding and abetting. The government must prove some affirmative participation by the aider and abettor.") (internal citation omitted). On the other hand, "there are circumstances where presence itself implies participation — as where a 250-pound bruiser stands silently by during an extortion attempt, or a companion stands by during a robbery, ready to sound a warning or give other aid if required." Ortiz, 966 F.2d at 712 (internal quotation omitted).

In the instant case, the government presented no direct evidence during its case in chief that de la Cruz-Paulino (1) had any knowledge that the garbage bags contained cocaine, (2) had any connection to the drugs prior to Andaluz suggesting to Diaz-Perez, during their 7:55 p.m. conversation, that she pay someone $40 to help her carry the packages to her car, or (3) was to be paid more than $40 for her involvement in the drug venture. The government argues that the jury was nevertheless entitled to find beyond a reasonable doubt that de la Cruz-Paulino aided and abetted Diaz-Perez in the possession of cocaine with intent to distribute because (1) criminals do not usually welcome nonparticipants as witnesses to their criminal activities and (2) the facts, especially her involvement in moving the packages from an apartment to Diaz-Perez's car and her statement about the police being around, imply that de la Cruz-Paulino knowingly participated in the venture and intended to help it succeed. We do not agree.

The evidence suggests that de la Cruz Paulino was brought in to do a menial task, namely carrying the cocaine from the apartment where it was stored down to Diaz-Perez's car. The government presented no evidence that de la Cruz-Paulino was involved prior to Andaluz suggesting to Diaz-Perez that she pay someone $40 to help her carry the packages to her car. No reasonable jury could have concluded, beyond a reasonable doubt, that Diaz-Perez would have hired only someone already participating in the drug venture to do this menial task and therefore that de la Cruz-Paulino was already involved. Accordingly, we must determine whether a reasonable jury could conclude beyond a reasonable doubt that de la Cruz-Paulino developed the specific intent to aid and abet Diaz-Perez in the approximately two hours between Andaluz's $40 suggestion and the ensuing arrests.

We do not think that the evidence supports the inference that de la Cruz-Paulino was told about and joined the drug venture after Andaluz's $40 suggestion. The drugs were elaborately wrapped in sealed packages that were then placed into three garbage bags. Unless she was a participant in the drug venture prior to Andaluz's suggestion, an inference we have held to be impermissible, de la Cruz-Paulino could not have seen the drugs in their unpackaged form. The drugs were assuredly packaged before Andaluz made the $40 suggestion, for the time period between that suggestion (made at 7:55 p.m.) and the actual arrest (at 9:55 p.m.) would have been too short to package and transport the drugs, especially given that Diaz-Perez spoke with Andaluz from her car during that time. There is also no indication from the taped conversations between Diaz-Perez and Andaluz that she had anything to do with the drugs other than move them down from the apartment to her car. While de la Cruz-Paulino admitted to helping carry "it" from the apartment to the car, responding to Salazar's question, "Did you get it down?" with "Of course we did," there is no evidence that de la Cruz-Paulino saw the packages inside the garbage bags until the time of her arrest.

We see no basis for concluding that Diaz-Perez cut de la Cruz-Paulino in on the drug transaction after soliciting her package-carrying services. Diaz-Perez had a menial job that de la Cruz-Paulino was willing to do for $40; there was no need for Diaz-Perez to cut de la Cruz-Paulino into the deal to obtain her package-carrying services. Cf. United States v. Francomano, 554 F.2d 483, 487 (1st Cir. 1977) (holding that there was "no basis for a reasonable inference" that the defendants were cut in on the drug deal when the record indicated that they were willing to perform the required crewmember services with "no special inducement"). The jury could not, without engaging in impermissible inference, conclude that de la Cruz-Paulino was entitled to anything other than $40 for her package-carrying services. Indeed, there is no evidence about Diaz-Perez's own compensation arrangement. As Diaz-Perez was not supposed to obtain any money from the government agents when she turned over the packages to them, there is no basis for inferring that de la Cruz-Paulino thought she would receive a portion of the funds collected.

Of course, an aider and abettor need not receive compensation or have any stake in a transaction to be convicted. See United States v. Winston, 687 F.2d 832, 834-35 (6th Cir. 1982). Thus, in United States v. Cuevas-Esquivel, 905 F.2d 510, 515 (1st Cir.), cert. denied, 498 U.S. 877, 111 S.Ct. 208, 112 L.Ed.2d 169 (1990), we upheld the conviction of a defendant who testified that he was only paid $33 for being a deckhand on board a boat carrying a large amount of marijuana. Similarly, in United States v. Steuben, 850 F.2d 859, 866 (1st Cir. 1988), we affirmed the conviction of a defendant who claimed that he was paid $300 for being a crewmember on board a tugboat carrying $42 million worth of marijuana. In both cases, however, we held that there was sufficient other evidence for the jury to conclude that the defendants were not just crewmembers, but rather full-fledged participants in the criminal ventures. Unlike those cases, the $40 payment in the instant case is corroborated by the fact that Andaluz suggested it, and there is little other evidence indicating that de la Cruz-Paulino was actually involved in the drug venture. Thus, while compensation of only $40 would not by itself counter other evidence establishing that de la Cruz-Paulino was a participant in the criminal venture, that compensation, especially suggested as it was by a government agent, tends to negate an inference that de la Cruz-Paulino was more heavily involved.

We next consider whether the fact that de la Cruz-Paulino overheard some of Diaz-Perez's telephone conversations and came to the Burger King delivery site is evidence that she was a full-fledged participant in the drug venture. It is true that "it runs counter to human experience to suppose that criminal conspirators would welcome innocent nonparticipants as witnesses to their crimes." United States v. Batista-Polanco, 927 F.2d 14, 18 (1st Cir. 1991). Thus, we have upheld convictions of defendants where the facts suggested that they witnessed open and obvious criminal activity and therefore allowed the inference that the defendants participated in that criminal activity. For example, in Batista-Polanco, we upheld the conviction of a defendant arrested at an apartment while a large-scale heroin-packaging operation was in process throughout the apartment, stating "we cannot accept the hypothesis that participants in a distribution scheme would permit a noncontributing interloper to remain for an extended period of time in a small apartment while their conspicuous criminal conduct continued unabated." Id. In that case, however, the presence of six seats — one a makeshift seat consisting of an overturned bucket with a cushion and one with the defendant's sweater on it — around the kitchen table at which the heroin was packaged also suggested that the defendant was a participant along with the five other men arrested at the apartment. Id.

On the other hand, a defendant who was present at the scene of a crime and who had knowledge that a crime was being committed cannot be convicted of aiding and abetting unless the jury can reasonably infer that the defendant shared the specific intent of the principal. The fact that criminal activity occurs in front of someone does not always allow the inference that that someone was a participant. Thus, in United States v. Paone, 758 F.2d 774, 776 (1st Cir. 1985), we suggested that if the defendant had merely been a passenger in the back seat of a car while drugs were handed over to a purchaser, rather than someone who was repeatedly present at important junctures of a drug deal, the evidence might have been insufficient to support his conviction.

We assume that de la Cruz-Paulino overheard Diaz-Perez's side of the three telephone conversations that took place after Andaluz suggested that she pay someone to help her carry the packages. We have scrutinized those conversations with care and find that they do not provide a basis for inferring that de la Cruz-Paulino shared Diaz-Perez's specific intent to possess cocaine for distribution. While they would support Diaz-Perez's conviction, especially since Andaluz used the word "kilos," we do not think that an innocent observer to Diaz-Perez's side of the conversations would infer that a drug transaction was being discussed. Nor do we think the fact that Diaz-Perez felt free to conduct her side of the conversation in front of de la Cruz-Paulino indicates that de la Cruz-Paulino was a participant in the drug venture, for Diaz-Perez could control her responses. Indeed, she did not speak explicitly about cocaine at any time. We note that Diaz-Perez did mention obtaining the $40 from the government agents during one of those conversations.

That de la Cruz-Paulino came to the Burger King delivery scene also does not indicate that she was a knowing participant in the drug venture. While criminals generally might be presumed not to bring along nonparticipants to witness their criminal activities, we do not think that necessarily holds true when the criminal activity will not be open and obvious. Compare Clotida, 892 F.2d at 1105 (reversing as insufficient the defendant's conviction for aiding and abetting her travelling companion in drug crimes involving cocaine-laden clothing mixed in suitcases with her own clothing). In this case, no negotiations were to be entered into and no money was to be exchanged: the government agents were simply supposed to take the car for a few minutes, unload it, and bring it back. Diaz-Perez responded to Andaluz's question, "Which is your car?" by stating, "That black one over there, in the trunk, two bales and . . . eight doubles. . . ." Then Andaluz and Salazar opened the trunk and one of the garbage bags, Andaluz saying that he had "[t]o check it out girl, because what will I do with [unintelligible]." Diaz-Perez became very upset and exclaimed, "Shut up! Oh God, the two bales and the other stuff." At this point, Andaluz stated, "No, relax, we are getting involved here to get a party," and then de la Cruz-Paulino stated, "No, watch out the police is around, going around here."

We do not think that de la Cruz-Paulino's comment, "No, watch out the police is around, going around here," is sufficient in this context to allow a reasonable jury to conclude that de la Cruz-Paulino specifically intended to aid and abet Diaz-Perez in possessing cocaine for distribution. Even if de la Cruz-Paulino could have inferred from Diaz-Perez's sudden shift in attitude and her statements about the "two bales," and from the two government agents' opening of one of the garbage bags, that, unbeknownst to her, a drug transaction was going on, such last-minute knowledge would not support the conclusion that she shared the specific intent to possess cocaine for distribution. See Francomano, 554 F.2d at 487 ("Even if it could be inferred that appellants acquired knowledge of the throwing of the packages [of marijuana] overboard, such last minute knowledge together with all other evidence produced by the Government affords no legal basis for appellants' conviction as aiders and abetters."); see also United States v. Lopez-Pena, 912 F.2d 1536, 1538 (1st Cir. 1989) (stating that warning about police in the area and advice on avoiding arrest were what "anyone might do as a friend").

The evidence in this case is close to the line of being enough to sustain a conviction. Nevertheless, in reversing de la Cruz-Paulino's conviction, we keep in mind the following:

[E]vidence might raise a question in a reasonable man's mind. But that is not enough. Guilt, according to a basic principle in our jurisprudence, must be established beyond a reasonable doubt. And, unless that result is possible on the evidence, the judge must not let the jury act; he must not let it act on what would necessarily be only surmise and conjecture, without evidence.

United States v. Campbell, 702 F.2d 262, 267 (D.C. Cir. 1983) (quoting Cooper v. United States, 218 F.2d 39, 42 (D.C. Cir. 1954)) (alteration in Campbell).

III. CONCLUSION

For the forgoing reasons, the conviction of Diaz-Perez is affirmed and the conviction of de la Cruz-Paulino is reversed.