This case comes before us on direct appeal from the defendant's conviction in the United States District Court for the Western District of Oklahoma. The defendant was charged with conspiracy to distribute cocaine and cocaine base, in violation of 21 U.S.C. § 846; possession of cocaine with intent to distribute, in violation of 21 U.S.C. § 841(a)(1); and travelling and causing travel in interstate commerce to facilitate the distribution and possession of cocaine and cocaine base with intent to distribute, in violation of 18 U.S.C. § 1952(a)(3) and 18 U.S.C. § 2. The case was tried to a jury, which found the defendant guilty on all counts. The defendant now appeals, asserting fifteen different errors below. We affirm.

The defendant was involved, along with a number of co-conspirators, in a drug trafficking ring that transported cocaine and cocaine base from Southern California to Oklahoma City, Oklahoma. The cocaine was then "cooked" and transformed into rock cocaine or "crack" and sold on the streets.

The police intercepted some portion of three transfers of narcotics between California and Oklahoma. In January of 1990, the defendant, accompanied by Vickie Hogg, one of the co-defendants, travelled to California from Oklahoma and acquired cocaine from J.C. Chatman, one of the co-defendants and the primary source for narcotics in California. Vickie Hogg purchased a one-way bus ticket to Oklahoma in the name of Stephen Smith and gave the ticket and the cocaine to Tashawn Kyle Cook at the Los Angeles Bus Depot. Cook was stopped, consented to a search of his luggage and the cocaine was discovered and confiscated.

On July 27, 1990, officers of the Oklahoma City Police Department, while on a narcotics interdiction assignment at the Will Rogers World Airport in Oklahoma City, observed the defendant, accompanied by Darren Hogg and Doris Wright, purchase tickets to Southern California. Darren Hogg was stopped at the security checkpoint where a dark and unidentifiable object was detected by the x-ray machine. He consented to a search of his bag where the police found $9,700 in cash. D. Hogg was informed that the money would be detained for inspection by a narcotics dog and that he was free to go.

The officers returned to where the defendant and Wright were standing and began to question them. They both denied being with the other or with D. Hogg. Wright at first consented to a search of her bag but once it had commenced told the officer to stop. The officer complied with her request. The officers informed the defendant and Wright that their bags would be detained until they could be inspected by a narcotics dog but that they were free to go. The bags were taken to another level of the airport and the parties followed, protesting that they had planes to catch. The defendant gave permission to search the bag he was carrying but denied that it was his. Wright then reauthorized the search of her bag. The police found $12,000 in cash and a portfolio containing letters to Vickie Hogg in the defendant's bag. The three individuals made their flight but their bags were detained.

On August 23, 1990, the defendant was stopped again at the Will Rogers Airport in Oklahoma City. The officers in Oklahoma had received information from an officer of the Dallas-Fort Worth task force that a passenger registered as Charles Smith had purchased a one-way ticket from Los Angeles to Oklahoma City with cash and suggested that he be stopped.1 The officers observed the defendant, whom they recognized from the airport incident on July 27, 1990, deplane and followed him to the baggage claim area. The defendant picked up a gift-wrapped box, which was marked with the name Charles Smith. The officers approached the defendant and began to question him. Although he claimed to have no identification, the defendant's plane ticket read Charles Smith. The defendant claimed that the box was not his, that it belonged to Larry Taylor, that he had no way of contacting Larry Taylor, and that it contained cookware.

The officers informed the defendant that both he and the box would be detained until a search warrant could be obtained. The defendant was escorted to the police office in the airport where he was subjected to a pat down search. The officers observed cigarette rolling papers in the defendant's open shirt pocket and when removed, observed marijuana in a cellophane envelope. The defendant was informed that he would be placed under arrest for possession of marijuana.2 At that time the defendant orally consented to the search of the box. However, because the defendant was unable to sign a consent form, the police instead made an application for a search warrant. Based in part on a positive alert from a narcotics detector dog, the search warrant was issued and the box was found to contain four 4,000 milliliter glass beakers as are commonly used in the cooking of crack cocaine.

On August 24, 1990, the Oklahoma City police were informed by the Los Angeles Police Department, who received the information through an informant, that the defendant was out on bond and was at an apartment on 46th Street in Oklahoma City cooking cocaine that he and his co-conspirators had brought in from California. The Oklahoma City police verified that the defendant was out on bond, learned that the apartment was rented to Vickie Hogg, and learned from the apartment manager that there was suspicious activity at the residence. The police obtained a search warrant and executed it on August 25, 1990; however, no drugs were found. Vickie Hogg was in the apartment when the warrant was served and the defendant and Tashawn Kyle Cook were found outside the apartment.

On February 28, 1991, a confidential informant notified the Oklahoma City Police Department that the defendant was the "main man" in the biggest narcotics ring in Oklahoma City, and that the defendant had just returned from California with half a kilogram of cocaine, and that he was in room 141 of the Comfort Inn in Oklahoma City. The officers obtained a search warrant and served it the same day. They found the defendant with a woman in the room. The defendant was searched and two bags of cocaine were found in his underwear. Two additional bags of cocaine were found in the box springs of the bed. The defendant was placed under arrest at that time.

The defendant was indicted along with Vickie Hogg on March 20, 1991. He was charged with conspiracy to distribute cocaine and cocaine base, in violation of 21 U.S.C. § 846 (count 1); possession of cocaine with intent to distribute, in violation of 21 U.S.C. § 841(a)(1) (counts 2 & 5); and travelling and causing the travel in interstate commerce to facilitate the distribution and possession of cocaine and cocaine base with intent to distribute, in violation of 18 U.S.C. § 1952(a)(3) and 18 U.S.C. § 2 (counts 3 & 4). On July 2, 1991, the court ordered the trial of Vickie Hogg and the defendant (No. CR-91-52-T) consolidated with the trial of Clara Gary, Lenanier Brown, J.C. Chatman, Ronnie Miller, and Kenneth Eugene Wright, each of whom had been indicted separately (No. CR-91-51-T). On July 16, 1991, the court granted the government's unopposed motion for the severance of the trial of Clara Gary and Lenanier Brown.3

The case was tried to a jury, and on September 30, 1991, the defendant was found guilty on all five counts. He was sentenced to life imprisonment on counts one and five, 480 months on count two, and 60 months on counts three and four. The sentences were ordered to run concurrently. The defendant filed a notice of appeal on October 3, 1991.

In this appeal the defendant alleges fifteen separate errors: 1) denial of the motion to suppress evidence seized at the airport on July 27, 1990; 2) denial of the motion to suppress the glass beakers seized at the airport on August 23, 1990; 3) admission of the beakers pursuant to an unlawful search warrant; 4) the unlawful introduction of evidence of a prior arrest that was suppressed at a pre-trial hearing; 5) failure to suppress evidence seized from the motel on February 28, 1991; 6) failure to excuse for cause a juror who was a former police officer; 7) unlawful admission of hearsay documents; 8) unlawful admission of evidence of other acts outside the conspiracy; 9) prosecutorial comments on the defendant's failure to testify; 10) insufficient evidence to support a guilty verdict; 11) cumulative error; 12) error in the calculation of the amount of cocaine distributed for sentencing purposes; 13) erroneous classification of the substances distributed as cocaine base; 14) the unlawful application of 21 U.S.C. § 841 and U.S.S.G. § 2D1.1., which he claims are void for vagueness; and 15) error in increasing his sentence under U.S.S.G. § 3B1.1(c) for serving as a leader or organizer.4 We affirm.

The first five of the defendant's allegations of error relate to the district court's admission of evidence that was acquired through searches and seizures at the Oklahoma City Airport on July 27, 1990, and August 23, 1990, and in a search of an Oklahoma City motel room on February 28, 1991. The defendant filed a motion before the district court on July 8, 1991, requesting that the court suppress this evidence. He also filed a forty page brief in support of this motion that set forth the same bases for suppression that now constitute the allegations of error on appeal. An evidentiary hearing was held on July 12, 1991, at which the defendant was present and represented by counsel. The court denied the defendant's motion on July 15, 1991, and on July 29, 1991, it issued an explanatory order to clarify the ruling. The court denied the defendant's motion to suppress as to all except the marijuana seized in the pat down search on August 23, 1990, and any statements made following that search.5

In reviewing the denial of a motion to suppress, we consider the evidence in the light most favorable to the government, and we accept the district court's findings of fact unless they are found to be clearly erroneous. United States v. Ibarra, 955 F.2d 1405, 1409 (10th Cir.1992); United States v. McAlpine, 919 F.2d 1461, 1463 (10th Cir.1990). We have undertaken our own review of the record, and we have reviewed the district court's explanatory order. We are unable to conclude either that any of the factual findings of the district court were clearly erroneous or that the district court made any errors of law.6II. Refusal to Grant a For-Cause Dismissal of a Juror Who Was a Former Police Officer

The defendant claims that it was error for the district court to refuse to dismiss for cause one of the jurors who was a former police officer. Whether an individual is qualified to serve as a fair and impartial juror is a decision that is firmly within the discretion of the district court. United States v. Grismore, 546 F.2d 844, 848 (10th Cir.1976). The decision to refuse a for-cause dismissal will only be disturbed on appeal upon a "clear showing of abuse of discretion." Id. at 848; see United States v. Chapman, 158 F.2d 417, 421 (10th Cir.1946).

We do not agree that there was an abuse of discretion in the instant case. The fact that a prospective juror was once a police officer is not grounds, ipso facto, for disqualification. See Mikus v. United States, 433 F.2d 719, 724 (2d Cir.1970) (membership in a police force is not grounds for automatic disqualification from a criminal jury); cf. Grismore, 546 F.2d at 849 (the fact that a prospective juror is the wife of a policeman does not warrant a for-cause dismissal). In the instant case the record reveals that the trial judge undertook a thorough examination of the potential juror, explored his potential prejudice, and satisfied himself of the juror's impartiality. The former officer testified that he had been out of law enforcement for over 12 years and that he did not feel that experience would have any impact on his assessment of the credibility of witnesses or the guilt of the defendant. Given the careful and thorough examination of the potential juror and the circumstances of this case, we find that the refusal to grant a for-cause dismissal was not an abuse of discretion.7

III. The Admission of Documents Alleged to Be Hearsay

On appeal, McIntyre alleges that the district court erroneously admitted five documents which should have been excluded as hearsay: two motel registration cards ("Exhibits 52 and 53"); a cellular phone application and record of calls ("Exhibit 24"); copies of nine Western Union money orders ("Exhibits 6a-i"); and an American Express receipt ("Exhibit 25"). In addition, McIntyre argues that the district court erred when it allowed testimony concerning five other documents that were allegedly hearsay even though it refused to admit those documents into evidence. These documents consisted of two apartment rental receipts ("Exhibits 18 and 19"); customer copies of several money order receipts ("Exhibits 20 and 44"); and a customer copy of a car rental receipt ("Exhibit 23").

Evidentiary rulings are committed to the discretion of the trial court and are only reviewed for an abuse of that discretion. United States v. Zimmerman, 943 F.2d 1204, 1211 (10th Cir.1991). Deference to the trial judge is heightened when reviewing rulings on questions of the admissibility of hearsay evidence. Boren v. Sable, 887 F.2d 1032, 1033 (10th Cir.1989). We review evidentiary rulings by considering the record as a whole. Id. at 1034.

Hearsay is defined as "a statement, other than one made by the declarant while testifying at the trial or hearing, offered in evidence to prove the truth of the matter asserted." Fed.R.Evid. 801(c). A statement is an "oral or written assertion ... of a person, if it is intended by the person as an assertion." Fed.R.Evid. 801(a). Hearsay evidence cannot be admitted unless it falls under an exception. Fed.R.Evid. 802.

The defendant objects to the admission into evidence of Exhibits 52 and 53, registration cards from two motels located in California.8 The documents were introduced to support the prosecution's theory that Vickie Hogg and at least one of the other conspirators travelled to California to purchase cocaine. The government offered these documents for the truth of the matter asserted, namely that Vickie Hogg checked into the two motels on the dates recorded and paid for the rooms. Accordingly, they are hearsay. See United States v. Jefferson, 925 F.2d 1242, 1252 (10th Cir.1991) ("a receipt introduced as evidence of payment for a good or service constitutes hearsay"); FDIC v. Roldan Fonseca, 795 F.2d 1102, 1110 (1st Cir.1986) (money order receipts inadmissible hearsay to prove payments had been made); United States v. Watkins, 519 F.2d 294, 296-97 (D.C.Cir.1975) (receipts for rent offered to prove defendant lived at address were offered for truth of matter asserted and therefore inadmissible hearsay).9

The district court admitted the arrival and departure log from the Magic Carpet Motel and the registration form of the Villa Viejo Motel under the business records exception to the hearsay rule, Federal Rule of Evidence 803(6).10 We turn first to the Magic Carpet records. As to the arrival and departure log from the Magic Carpet Motel, the defendant failed to make a proper objection at trial to the admission of the document. Accordingly, we review the district court's determination for plain error. Fed.R.Evid. 103(a)(1), (d); United States v. Thody, 978 F.2d 625, 631 (10th Cir.1992).11

The owner of the Magic Carpet Motel testified that the log was kept in the regular course of business. However, the owner also testified that an employee of the motel filled in the log based on information received from the guest. Because the motel employee relied on information received from the guest in compiling the log, the record poses a hearsay problem.

The essential component of the business records exception is that each actor in the chain of information is under a business duty or compulsion to provide accurate information. See 2 McCormick on Evidence, § 290 at 274 (John William Strong, ed., 4th ed. 1992) (stating that the underlying theory of the business records exception is "a practice and environment encouraging the making of accurate records. If any person in the process is not acting in the regular course of business, then an essential link in the trustworthiness chain fails, just as it does when the person feeding the information does not have firsthand knowledge.")In order for the business records exception to apply, Rule 803(6) requires "an informant with knowledge acting in the course of the regularly conducted activity." Fed.R.Evid. 803(6), Advisory Committee Notes on 1972 Proposed Rules. The notes of the Advisory Committee on the 1972 Proposed Rules state:

Sources of information presented no substantial problem with ordinary business records. All participants, including the observer or participant furnishing the information to be recorded, were acting routinely, under a duty of accuracy, with employer reliance on the result, or in short "in the regular course of business." If, however, the supplier of the information does not act in the regular course, an essential link is broken; the assurance of accuracy does not extend to the information itself, and the fact that it may be recorded with scrupulous accuracy is of no avail. An illustration is the police report incorporating information obtained from a bystander: the officer qualifies as acting in the regular course but the informant does not. The leading case, Johnson v. Lutz, 253 N.Y. 124, 170 N.E. 517 (1930), held that a report thus prepared was inadmissible. Most of the authorities have agreed with the decision.

In the instant case, the motel clerk relied on the guest, who was not under a business duty or compulsion, to provide the information that went into the document. Therefore, the document presents hearsay problems.

However, the fact that the name on the registration was obtained from an actor not under a business compulsion does not necessarily mean the business records exception is inapplicable. If the business entity has adequate verification or other assurance of accuracy of the information provided by the outside person, the exception may still apply. Some courts have required that the business employee recording the information be "able in some way to verify the information provided--for example, by examining a credit card, driver's license, or other form of identification." United States v. Lieberman, 637 F.2d 95, 101 (2d Cir.1980); see United States v. Zapata, 871 F.2d 616, 625 (7th Cir.1989); 2 McCormick on Evidence § 290 at 275. We do not feel that in every case there must be direct testimony that an employee actually verified the information, nor is it necessary that there be an express policy that identification be checked. In some cases, the interests of the business may be such that there exists a sufficient self-interest in the accuracy of the log that we can find its contents to be trustworthy. See FDIC v. Staudinger, 797 F.2d 908, 910 (10th Cir.1986) (" '[a] foundation for admissibility may at times be predicated on judicial notice of the nature of the business and the nature of the records as observed by the court.' ") (quoting Weinstein's Evidence p 803(6) at 803-179 to -181 (1985)); Manufacturers and Traders Trust Co. v. Goldman (In re Ollag Constr. Equip. Corp.), 665 F.2d 43, 46 (2d Cir.1981) (finding information on financial statements provided to a bank in the regular course of the bank's business to be sufficiently trustworthy to qualify as business records, in part because providing of false information under such circumstances is subject to criminal sanctions; the court contrasted such information to that provided by hotel guests, where there is no similar indicia of reliability). However, in the instant case we do not find adequate guarantees of trustworthiness in the financial self-interests of the motel. Moreover, there was no evidence either that the identity of the individual claiming to be Vickie Hogg was actually checked or that there was a policy to do so. Nor do we find it persuasive that a motel employee transcribed the information rather than the guest.12

Although the admission of the Magic Carpet log may have been erroneous, we nevertheless are not convinced that it amounted to plain error. To constitute plain error, the district court's error in admitting the document must have been "both obvious and substantial." United States v. Jefferson, 925 F.2d 1242, 1254 (10th Cir.1991) (quoting United States v. Brown, 555 F.2d 407, 420 (5th Cir.1977)). In light of our previous discussion, we do not find the error in admitting the Magic Carpet Motel records to be obvious. Accordingly, we find that the admission of the Magic Carpet log was not plain error.

The district court also admitted the registration card and folio receipt from the Villa Viejo Motel under the business records exception to the hearsay rule. See Fed.R.Evid. 803(6).13 The office manager of the motel testified that those records were kept in the normal course of business, and that, although a portion of the registration card was filled out by a guest, the motel enforced a policy of verifying the identity of guests by examining driver's licenses. Consequently, we find that the Villa Viejo records were properly admitted under the business records exception to the hearsay rule. See Lieberman, 637 F.2d at 101; Zapata, 871 F.2d at 625.

The defendant objects to the admission into evidence of Exhibits 6(D)-(I), copies of money order receipts that were subpoenaed from Western Union.14 The copies of the money order receipts were offered by the government to show the means of money transfer and the involvement of certain individuals in the conspiracy. The documents were therefore offered for the truth of the matter asserted on the face of the receipts and are hearsay. See United States v. Jefferson, 925 F.2d 1242, 1252 (10th Cir.1991) ("a receipt introduced as evidence of payment for a good or service constitutes hearsay"); see also FDIC v. Roldan Fonseca, 795 F.2d 1102, 1110 (1st Cir.1986) (money order receipts inadmissible hearsay to prove payments had been made); United States v. Watkins, 519 F.2d 294, 296-97 (D.C.Cir.1975) (receipts for rent offered to prove defendant lived at address and therefore offered for truth of matter asserted).

Exhibits 6(D)-(I) were introduced by the government through an employee of Western Union. The Western Union district manager testified the records were kept in the ordinary course of business. He also testified that although no identification was required to send money, identification would be required to pick up the money under the circumstances of these transfers. The defendant objected that, because the documents were being offered to prove the identities of senders and recipients of money, and there was no attempt by Western Union to verify the identities of the senders and recipients, the business records exception did not apply. The district court admitted the documents finding that the objection was "appropriate for cross examination. It goes to the credibility of the exhibit and the witness. But, not to its admissibility." This decision was partially in error.

Because Western Union did not have a policy of verifying the identity of senders, and because it is apparent from the testimony brought out at trial that senders could easily use aliases, the documents were inadmissible to prove the identity of senders of money. See United States v. Bland, 961 F.2d 123, 126-27 (9th Cir.) (registration form for handgun purchase was business record because identity of registrant was verified), cert. denied, --- U.S. ----, 113 S. Ct. 170, 121 L. Ed. 2d 117 (1992); United States v. Patrick, 959 F.2d 991, 1000-02 (D.C.Cir.1992) (receipt not business record to show purchaser identity because no showing that purchaser identity was verified); United States v. Zapata, 871 F.2d 616, 625-26 (7th Cir.1989) (hotel registration was a business record because standard practice of hotel was to verify guest's identity); United States v. Lieberman, 637 F.2d 95, 101 (2d Cir.1980) (hotel registration not business record because no evidence that guest's identity was verified or that practice of hotel was to do so). However, because Western Union required the verification of identity to receive money, the documents were admissible to prove the identity of the recipients.

Accordingly, the defendant was entitled to an instruction limiting the use of the documents to identification of recipients of the money. But, it does not appear from the record that the defendant requested such an instruction. We therefore will only reverse on this basis if there was plain error affecting the defendant's substantial rights. United States v. Fingado, 934 F.2d 1163, 1166 (10th Cir.), cert. denied, --- U.S. ----, 112 S. Ct. 320, 116 L. Ed. 2d 262 (1991); United States v. Petermen, 841 F.2d 1474, 1481 (10th Cir.1988), cert. denied, 488 U.S. 1004, 109 S. Ct. 783, 102 L. Ed. 2d 774 (1989). Under the facts of this case we conclude that the admission of the evidence did not amount to plain error.

C. Evidence Pertaining to the Existence and Location of Certain Documents Rather Than to the Assertions Contained Therein

At trial the government had planned to offer into evidence two apartment rental receipts ("Exhibits 18 and 19"), customer copies of several money order receipts ("Exhibits 20 and 44"), an American Express receipt ("Exhibit 25"), and a customer copy of a car rental receipt ("Exhibit 23"). The documents had been found in Vickie Hogg's car, luggage, and apartment. The government had planned to offer the evidence to link the defendants together in a common scheme and to connect them to certain locations. The court considered each of these documents in camera, and, with the exception of the American Express receipt, refused to allow them into evidence on hearsay grounds. The court, however, did allow the police officer who found the documents to testify concerning the names and addresses contained in the documents and where the documents were found. The court reasoned that testimony regarding the documents and where they were found, if offered to link the defendants together and to certain locations, did not pose hearsay problems because it was not offered for the truth of the matter asserted.15 Although few courts have considered the issue in any detail, the overwhelming majority of courts, including several panels of this Circuit, have concluded with little discussion that circumstantial evidence16 is not hearsay under the Federal Rules of Evidence.17 Furthermore, academic and practical writings are in agreement that such evidence is not hearsay under the rules.18

Important guidance is offered in the Notes of the Advisory Committee on 1972 Proposed Rules. The Notes explain how Fed.R.Evid. 801(c) was intended to be applied as follows:

It can scarcely be doubted that an assertion made in words is intended by the declarant to be an assertion. Hence verbal assertions readily fall into the category of "statement." Whether nonverbal conduct should be regarded as a statement for purposes of defining hearsay requires further consideration. Some nonverbal conduct, such as the act of pointing to identify a suspect in a lineup, is clearly the equivalent of words, assertive in nature, and to be regarded as a statement. Other nonverbal conduct, however, may be offered as evidence that the person acted as he did because of his belief in the existence of the condition sought to be proved, from which belief the existence of the condition may be inferred. This sequence is, arguably, in effect an assertion of the existence of the condition and hence properly includable within the hearsay concept.... Admittedly evidence of this character is untested with respect to the perception, memory, and narration (or their equivalents) of the actor, but the Advisory Committee is of the view that these dangers are minimal in the absence of an intent to assert and do not justify the loss of the evidence on hearsay grounds. No class of evidence is free of the possibility of fabrication, but the likelihood is less with nonverbal than with assertive verbal conduct. The situations giving rise to the nonverbal conduct are such as virtually to eliminate questions of sincerity. Motivation, the nature of the conduct, and the presence or absence of reliance will bear heavily on the weight to be given the evidence.... Similar considerations govern nonassertive verbal conduct and verbal conduct which is assertive but offered as a basis for inferring something other than the matter asserted, also excluded from the definition of hearsay by the language of subdivision (c).

Fed.R.Evid. 801(c), Notes of the Advisory Committee on 1972 Proposed Rules (citations omitted) (emphasis added).

Here, the American Express receipt and the testimony about Exhibits 18, 19, 20, 23, and 44 were introduced only to link various of the defendants together by the "circumstance" that documents bearing the names of certain defendants or the location of certain drug transactions were found in Vickie Hogg's possession. That testimony did not depend upon the truth of the assertions contained in the documents, and consequently we conclude such evidence was not hearsay as defined by Fed.R.Evid. 801(c).19

D. The Cellular Phone Application and Record of Calls

The defendant objects to the admission into evidence of Exhibit 24, an application for cellular phone service and record of calls under the account name Vickie Hogg.20 The documents were introduced to establish that Vickie Hogg had a cellular phone and that she used that phone to contact her co-conspirators in California, and to show that she travelled to, and used her cellular phone in, California.21 As such they were offered for the truth of the matter asserted and were hearsay. See United States v. Jefferson, 925 F.2d 1242, 1252 (10th Cir.1991) ("a receipt introduced as evidence of payment for a good or service constitutes hearsay"); see also FDIC v. Roldan Fonseca, 795 F.2d 1102, 1110 (1st Cir.1986) (money order receipts inadmissible hearsay to prove payments had been made); United States v. Watkins, 519 F.2d 294, 296-97 (D.C.Cir.1975) (receipts for rent offered to prove defendant lived at address and therefore offered for truth of matter asserted).

The district court admitted the application on the grounds that it was an admission.22 However, this basis for introduction of the documents was error. Because the government never verified the signatures on the application, the document was improperly admitted as the admission of a party opponent. See United States v. Markopoulos, 848 F.2d 1036, 1039 (10th Cir.1988).23

Similarly, although the District Client Service Supervisor for Cellular One testified that the documents were kept in the regular course of business, there was no evidence that there was a policy requiring customers to show identification when signing up for the service. In fact, the Cellular One employee admitted that anyone could have opened this account under the name Vickie Hogg. Furthermore, the application was not taken by a Cellular One employee, but rather by an independent contractor. Accordingly, we find that it was error to admit the document as a business record under Fed.R.Evid. 803(6). See United States v. Patrick, 959 F.2d 991, 1000-02 (D.C.Cir.1992); United States v. Lieberman, 637 F.2d 95, 101 (2d Cir.1980); cf. United States v. Bland, 961 F.2d 123, 126-27 (9th Cir.1992); United States v. Zapata, 871 F.2d 616, 625 (7th Cir.1989).

This does not end our analysis, however, because we must determine whether this error was harmless. In determining whether a particular error is harmless, there are two standards of review: the nonconstitutional harmless error standard of review pursuant to Fed.R.Crim.P. 52(a), or the constitutional standard established in Chapman v. California, 386 U.S. 18, 24, 87 S. Ct. 824, 828, 17 L. Ed. 2d 705 (1967). The record does not indicate that the defendants made constitutional objections to the admission of the document at trial. Rather, they made only general hearsay objections under the Federal Rules of Evidence. See United States v. Perez, 989 F.2d 1574, 1582 (10th Cir.1993) (en banc). Although defendants make broad assertions of constitutional violations in their briefs, as this court noted in Jefferson, "[a] violation of the hearsay rule does not automatically equate to a violation of the Sixth Amendment."24 925 F.2d at 1254. Accordingly, we apply the nonconstitutional standard of harmless error in this case.

The document in question related only to collateral matters, and the prosecution offered it only as circumstantial proof of association among the defendants and to link the defendants with places that drugs were distributed. Furthermore, in light of the direct testimony identifying McIntyre as the leader of the drug operation, we find the Cellular One documents to be cumulative. In fact, the Cellular One application does not directly implicate McIntyre at all.25 Given the strength of the other evidence and the nature of the documents in question, we find that the admission of the cellular phone application did not affect the outcome of the trial and therefore consider it to be harmless error.

IV. The Admission of Evidence of Other Acts Outside the Conspiracy

The defendant further objects that the district court erred when it allowed Talisha Woods to testify, over the objection of defense counsel, that she and D. Hogg had obtained cocaine from the defendant in October of 1989.26 The indictment charges that the conspiracy originated "on or about March 1990, the exact date being unknown to the Grand Jury." Before trial, the defendant filed a brief and Request for Notice of Intention to Introduce Similar Acts Under Fed.R.Evid. 404(b), which was denied on July 15, 1991. At trial, the defendant objected to the introduction of the evidence as outside the period of the conspiracy. The district court declined to grant a mistrial and instructed the jury that the evidence might be relevant for purposes of the witnesses' knowledge of the defendants and the way the business may have worked, but that the event fell outside the time period of the indictment so it could not be considered for purposes of guilt or innocence.

We review the admission of prior acts evidence under an abuse of discretion standard. United States v. Jefferson, 925 F.2d 1242, 1257 (10th Cir.1991). Federal Rule of Evidence 404(B) states that

Evidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show action in conformity therewith. It may, however, be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident....

In Jefferson we held that where testimony meets the following four requirements we will presume that there is no undue prejudice:

(1) the evidence must be offered for a proper purpose; (2) the evidence must be relevant; (3) the trial court must make a Rule 403 determination of whether the probative value of the similar acts is substantially outweighed by its potential for unfair prejudice; and (4) pursuant to Fed.R.Evid. 105, the trial court shall, upon request, instruct the jury that the evidence of similar acts is to be considered only for the proper purpose for which it was admitted.

Jefferson, 925 F.2d at 1258.

Our review of the record in this case reveals no error. The testimony was both proper and relevant to the government's case. We agree with the district court's finding that it established the basis of the witness' knowledge and her relationship with the defendant as well as the existence of the conspiracy itself. We cannot say, in light of the abundance of testimony that had been introduced about similar drug transactions, that the district court abused its discretion when it found that the testimony was not prejudicial to the defendant. Finally, the district court gave an appropriate limiting instruction. Accordingly, we find that the admission of the prior acts evidence in the instant case does not amount to an abuse of discretion on the part of the trial court.

V. Comments by the Prosecutor on the Defendant's Failure to Testify

The defendant alleges that his Fifth Amendment rights were violated when the prosecutor commented on his refusal to testify. See Griffin v. California, 380 U.S. 609, 85 S. Ct. 1229, 14 L. Ed. 2d 106 (1965). Because we find that the prosecutor did not comment on the defendant's choice not to testify, we find that there was no violation of the defendant's constitutional rights.

In closing arguments the defense counsel argued:

Let's talk about the Comfort Inn where Mr. McIntyre was arrested with this in his shorts.

Who was the person--and let me say this first. Sometimes in a case like this or in any case, the most important witness there can ever be is the one that doesn't testify. That's the witness that can scream from the top of the Courthouse what the truth is and the Government didn't choose to call Redonna Hill as a witness.

And the reason that they didn't is Officer Eastridge told you what she told him after she was arrested. She said the drugs under the mattress is mine.

First, I think she said she didn't know whose they were. But then she said they are my drugs. I got them over at this chicken restaurant from some guy and I was going to sell them for him.

There's no reason to call her. It is obvious why the Government didn't. Why repeat something that's damaging to your case.

Why would the defendant call them as a witness? We don't need to. She's already said they were her drugs.

R. Vol. X at 124. The prosecution then responded in rebuttal:

If defense counsel wished to have a witness stand and scream at the top of the Courthouse, the truth, they are certainly capable. And we would more than welcome such an individual.

But that wasn't done.

The truth is what you heard from the witnesses that have testified.

R. Vol. X at 155-56. Defense counsel objected to these comments, claiming that would be construed as a comment on the defendant's failure to testify. Defense counsel requested either an admonition that the jury disregard the prosecutor's remarks or a mistrial. The court disagreed with defense counsel's characterization of the remark. Nevertheless, he explained "I do and will instruct that the Defendants [sic] silence is not to be considered against the Defendants."27 R. Vol. X at 169.

In Knowles v. United States, 224 F.2d 168, 170 (10th Cir.1955) this court established that a statement is improper if "the language used was manifestly intended or was of such character that the jury would naturally and necessarily take it to be a comment on the failure of the accused to testify." The prosecutor's comments were not a commentary on the defendant's refusal to testify. Rather they were an answer to the defense counsel's inference that the prosecution failed to call Redonna Hill because she would have told the truth about the drugs found in the defendant's possession.28

The defendant next asserts that the evidence brought out at trial was insufficient to support his convictions under each of the five counts. In evaluating the sufficiency of the evidence on appeal we examine the record in the light most favorable to the government to determine if the evidence--both direct and circumstantial, together with all the reasonable inferences to be drawn therefrom--is such that a reasonable jury could find guilt beyond a reasonable doubt. Glasser v. United States, 315 U.S. 60, 80, 62 S. Ct. 457, 469, 86 L. Ed. 680 (1942); United States v. Hooks, 780 F.2d 1526, 1529 (10th Cir.), cert. denied, 475 U.S. 1128, 106 S. Ct. 1657, 90 L. Ed. 2d 199 (1986). We are bound to accept the resolution of conflicting evidence and the assessment of the credibility of witnesses as they are found by the trial judge as the trier of fact. United States v. Youngpeter, 986 F.2d 349, 353 (10th Cir.1993); United States v. Espinosa, 771 F.2d 1382, 1391 (10th Cir.), cert. denied, 474 U.S. 1023, 106 S. Ct. 579, 88 L. Ed. 2d 561 (1985). Moreover, "[a] criminal conviction may be sustained on wholly circumstantial evidence." Hooks, 780 F.2d at 1529.

Under count one, the defendant argues that the evidence was insufficient to establish conspiracy to distribute cocaine. He assumes incorrectly as the basis for this argument however that the evidence challenged in Sections I, III, and IV, supra, would be found to have been admitted in error. Furthermore, he would have us reassess and reweigh the testimony of Darren Hogg in contravention of this court's rulings in Youngpeter, 986 F.2d at 353, and Espinosa, 771 F.2d at 1391.

Under counts two and five, the defendant argues that the evidence offered at trial is insufficient to establish possession with intent to distribute. In considering the sufficiency of the evidence under count two, he would again have us reassess and reweigh the testimony of two of his co-conspirators in contravention of Youngpeter, 986 F.2d at 353, and Espinosa, 771 F.2d at 1391. Furthermore, the uncorroborated testimony of a co-conspirator, so long as it is not incredible or unsubstantial, is sufficient evidence on which to base a conviction. United States v. Sigal, 572 F.2d 1320, 1324 (9th Cir.1978). In considering the evidence under count five, the defendant argues that his mere presence in room 141 of the Comfort Inn on February 28, 1991, is insufficient to support his conviction for possession of the drugs found under the mattress.29 However, the fact that the defendant was found in possession of marijuana, with cocaine concealed on his person,30 and was lying on the bed in which the additional cocaine was found is circumstantial evidence from which a reasonable jury could conclude that he was in actual or constructive possession of all the cocaine found in the room. Furthermore, the large quantity of cocaine found in the motel room is sufficient to support a judgment that the defendant intended to distribute cocaine. See United States v. Hooks, 780 F.2d 1526, 1532 (10th Cir.1986) (citing United States v. Gonzalez, 700 F.2d 196, 204 (5th Cir.1983)).

In counts three and four, the defendant argues that the evidence is insufficient to establish either that he caused interstate travel to facilitate unlawful activity or that he aided and abetted. Again he erroneously assumes that the evidence objected to in Sections I and III, supra, would be excluded.31 This evidence alone would have been sufficient because as this court has recognized a conviction for aiding and abetting may rest upon circumstantial evidence. United States v. Maldonado-Campos, 920 F.2d 714, 716 (10th Cir.1990). Furthermore, even without that physical evidence, direct testimony on the record indicates that McIntyre directed the interstate transportation of drugs.

After a thorough review of the record we conclude that the evidence is sufficient to support the defendant's conviction under counts one through five.

Next, the defendant would have us consider the cumulative effect of the errors committed at trial. As we held in United States v. Rivera, 900 F.2d 1462, 1471 (10th Cir.1990), cumulative-error analysis evaluates only the effect of matters found to be errors, not the cumulative effect of non-errors. Here, aside from some wrongly admitted evidence, the defendant has failed to prove there were errors in his trial. We do not find that the cumulative effect of the wrongly admitted evidence rises to such a level that it had a "substantial influence" on the outcome of the trial, nor does it leave us with "grave doubt" as to whether it had such effect under the nonconstitutional harmless error analysis of Kotteakos v. United States, 328 U.S. 750, 765, 66 S. Ct. 1239, 1248, 90 L. Ed. 1557 (1946).

VIII. Quantity of Cocaine Attributed to McIntyre

The defendant next alleges that the district court erred in determining the quantity of cocaine to be used in setting his base offense level. We review the sentencing court's factual determinations under a clearly erroneous standard. United States v. Easterling, 921 F.2d 1073, 1077 (10th Cir.1990), cert. denied, --- U.S. ----, 111 S. Ct. 2066, 114 L. Ed. 2d 470 (1991). The quantum of proof necessary to support a finding of fact under the sentencing guidelines is a preponderance of the evidence. United States v. Rutter, 897 F.2d 1558, 1560 (10th Cir.), cert. denied, 498 U.S. 829, 111 S. Ct. 88, 112 L. Ed. 2d 60 (1990). Estimates are an acceptable method of calculating drug quantities so long as the information supporting the estimate has a minimum indicia of reliability. Easterling, 921 F.2d at 1077.

The defendant first asserts that the trial court improperly relied on Darren Hogg's testimony, which he alleges was untrustworthy because of internal inconsistencies. Again, this court will not reexamine the credibility of a witness' testimony nor will we decide between competing interpretations of testimony. United States v. Youngpeter, 986 F.2d 349, 353 (10th Cir.1993); Espinosa, 771 F.2d at 1391.32 Furthermore, the district court only attributed 15 kilos to McIntyre in calculating his base offense level, while both Darren Hogg's testimony and the presentence report suggest that between 20 and 24 kilos were actually attributable to McIntyre.

Second, the defendant argues that the cocaine found in the bed mattress at the Comfort Inn on February 28, 1990, was wrongly attributed to him. For the reasons that we find the evidence sufficient to support his conviction under Count 5, supra Section VI, we find that it was properly included in calculating his base offense level.

The defendant also claims that the district court erred in finding that the substances attributed to McIntyre were cocaine base rather than cocaine hydrochloride (HC1 sub2 ).33 Under the sentencing guidelines, possession and distribution of cocaine base or "crack" is more severely punished, and McIntyre argues that the district court erred in not presuming that all cocaine that was not tested by a chemist was cocaine hydrochloride (powder) for purposes of sentencing. See U.S.S.G. § 2D1.1; see also 21 U.S.C. § 841(b)(1)(A)(iii). We disagree.

The calculation of quantities of drugs for purposes of sentencing is reviewed for clear error. United States v. Slater, 971 F.2d 626, 638 (10th Cir.1992). The record supports the finding that the drugs possessed by McIntyre were in the form of cocaine base. In his testimony, Darren Hogg consistently refers to the substances possessed by McIntyre as crack cocaine. This court has held that mere testimony concerning the substance is sufficient to support a finding that it is crack rather than cocaine hydrochloride. See, e.g., United States v. LeRoy, 944 F.2d 787, 790 (10th Cir.1991); United States v. Anthony, 944 F.2d 780, 782 (10th Cir.1991). That Darren Hogg also referred to powder cocaine in his testimony does not persuade us otherwise; in those instances, he was referring to McIntyre transporting cocaine powder from California and cooking the powder into crack.34

The defendant next challenges the application of 21 U.S.C. § 841 and U.S.S.G. § 2D1.1 as void for vagueness. He asserts that the use of the term "cocaine base" is unconstitutionally vague and deprives him of his Fifth Amendment right to due process. This court has squarely addressed the constitutionality of the use of the term "cocaine base" and found it to be sound. United States v. Turner, 928 F.2d 956, 959-60 (10th Cir.), cert. denied, --- U.S. ----, 112 S. Ct. 230, 116 L. Ed. 2d 187 (1991). The defendant would have us distinguish Turner on the ground that in that case the party did not contend that the substance he possessed was inaccurately classified as cocaine base. However, subsequent to our opinion in Turner, this court has rejected that distinction and reaffirmed our holding. See United States v. Slater, 971 F.2d 626, 638-39 (10th Cir.1992). Accordingly, we reaffirm the holdings of Turner and Slater, and hold that the use of the term "cocaine base" does not encourage arbitrary and discriminatory enforcement, and was not vague as applied to the defendant's conviction and sentence in this case.

The defendant finally contends that the district court erred when it enhanced the defendant's sentence for serving as an organizer or leader under U.S.S.G. § 3B1.1(c). We review the district court's factual findings regarding the role of the defendant under a clearly erroneous standard. United States v. Beaulieu, 893 F.2d 1177, 1181-82 (10th Cir.), cert. denied, 497 U.S. 1038, 110 S. Ct. 3302, 111 L. Ed. 2d 811 (1990). Having reviewed the record, we cannot conclude that the district court clearly erred in finding that McIntyre was a leader and organizer under U.S.S.G § 3B1.1. McIntyre was clearly the key figure in the transportation of cocaine from California to Oklahoma; he solicited and directed the involvement of the participants in the conspiracy; and he accepted the proceeds of sales through middlemen and was involved with partnerships with other drug dealers.

For the forgoing reasons, the defendant's conviction and sentence are AFFIRMED.

SUPPLEMENTAL ORDER MODIFYING EARLIER OPINION AND DENYING

Aug. 18, 1993.

EBEL, Circuit Judge.

We have before us a Petition for Rehearing and a Suggestion for Rehearing En Banc filed by counsel for the defendant. In addition, we have allowed the defendant to file a pro se Petition for Rehearing and a Suggestion for Rehearing En Banc.1

In his pro se petition for rehearing, the defendant argues more forcefully than he did in his Pro Se Supplemental Reply Brief on direct appeal that he was denied the effective assistance of trial counsel in violation of the Sixth Amendment. In particular the defendant claims that, in the course of closing arguments, his trial counsel conceded that the defendant was guilty of certain crimes charged in the indictment to which he had plead not guilty.

The Tenth Circuit has adopted a general policy that claims of ineffective assistance of counsel are best addressed on collateral attack where a complete evidentiary record can be established. See Beaulieu v. United States, 930 F.2d 805, 806-07 (10th Cir.1991); Osborn v. Shillinger, 861 F.2d 612, 622-23 (10th Cir.1988). The defendant's pro se petition for rehearing convinces us that the issues he raises concerning defense counsel's improper closing remarks before the jury and any other claims of ineffective trial counsel are best addressed in collateral proceedings. See Strickland v. Washington, 466 U.S. 668, 691, 104 S. Ct. 2052, 2066, 80 L. Ed. 2d 674 (1984) ("an inquiry into counsel's conversations with the defendant might be critical"). Accordingly, we AMEND our prior opinion to dismiss the defendant's ineffectiveness of counsel claim without prejudice to his ability to raise that issue in a collateral attack.

In all other respects the Petitions for Rehearing and Suggestions for Rehearing En Banc are DENIED.