Chаrles Covington was convicted of one count of conspiracy to possess with intent to distribute crack cocaine, in violation of 21 U.S.C. § 846 (1994), and one count of possession with intent to distribute crack cocaine, in violation of 21 U.S.C. § 841(a)(1) (1994). Covington appeals his convictions and sentence, making several claims of error. We affirm the convictions but remand for resen-tencing.
I.
In June 1996 Charles Covington and Floyd Woods, two Alton, Illinois, residents, agreed to travel to California to buy crack cocaine from a man Covington knew named “Tank,” a former resident of Alton. Covington and Woods traveled with three associates, James-cina Williams, Beverly Bryant, and Maurice Pittman.
The group flew to Las Vegas, Nevada, on June 24,1996. The next day, the group took a bus to San Bernardino, California, where Woods and Covington met with Tank. Tank introduced them to an anonymous source, who sold them thirty ounces of crack cocaine. Woods then purchased a handgun from Tank for three ounces of the crack.
Because of the handgun, the group decided to return to Illinois via train. During the train ride, Woods put the crack cocaine in Williams’s purse. When the group arrived in Kansas City, Missouri, on June 28, 1996, Kansas City police were performing a routine drug interdiction procedure at the train station. Covington, Woods, and their three associates, concerned about the police, left the *642 train and scattered. Woods abandoned his gun in the lobby of the train station, and the gun was found by officers. Williams fled when she saw police officers and threw her purse in the bushes, but she was apprehended and 832.17 grams of crack cocaine was discovered in her purse. Although Cov-ington was questioned at the train station, he was released and was not arrested until later.
During trial, both Williams and Woods testified against Covington for the government, describing the details of the group’s trip to California to buy crack cocaine. The jury convicted Covington of possession with intent to distribute cocaine base and conspiracy to possess with intent to distribute cocaine base. Covington was sentenced as a career offender to 360 months imprisonment.
On appeal, Covington makes several challenges to his conviction and sentence. Through counsel, Covington contends that (1) he was incorrectly sentenced as a career offender under U.S. Sentencing Guidelines Manual § 4B1.1, (2) the evidence at his sentencing was insufficient to show that he possessed crack cocaine rather than another type of cocaine base, (3) there was insufficient evidence to convict him of conspiracy, (4) the court erred in giving a deliberate ignorancе jury instruction, and (5) the court erred in denying a mistrial after witnesses spoke to each other in violation of Federal Rule of Evidence 615. We consider these arguments in turn. 1
II.
Covington first contends that the district court erred by sentencing him as a career offender under U.S. Sentencing Guidelines Manual § 4B1.1. Covington argues that he was not imprisoned for twо prior qualifying offenses within the fifteen-year period ending when he committed the instant offenses. A district court’s “determinations with respect to the offenses in a criminal history computation are factual determinations and are subject to a ‘clearly erroneous’ standard of review.”
United States v. Lowe,
A defendant qualifies as a careеr offender when being sentenced for a crime of violence or a controlled substance offense if the defendant “has at least two prior felony convictions of either a crime of violence or a controlled substance offense.” U.S.S.G. § 4B1.1 (1995). The two prior felony convictions must each have “resulted in the defendant being incarcerated during any part of [the] fifteen-year period” ending when the defendant’s instant offense commenced. U.S.S.G. § 4A1.2(e)(1) (1995); see U.S.S.G. § 4B1.2, comment, (n.4) (1995) (instructing courts to apply U.S.S.G. § 4A1.2 to determine if an offense counts in the career offender calculation). If a defendant qualifies as a career offender, the defendant’s offense level can be increased, and the defendant’s criminal history category is increased to Category VI. In Covington’s ease, career offender qualification did not result in his offense level being increased, but resulted in an increase of his criminal history category from IV to VI. 2
Because Covington commenced the instant offense in June 1996, he must have been incarcerated for two qualifying offenses between June 1981 and June 1996 to qualify as a career offender. The district court found that Covington qualified as a career offender based on two prior Illinois convictions. The first conviction was for an aggravated kidnaping committed by Covington in 1983 аnd is not challenged as a basis for career offender status. The second conviction was for a burglary committed by Cov-ington in 1975. Covington was imprisoned for the burglary conviction beginning in March 1978, and was released on parole soon thereafter in September 1978. In December 1979, while on parole, Covington committed
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Illinois firearm offenses, and was again imprisoned.
3
In April 1980, an Illinois court sentenced Covington to five years custody on the firearm offenses, and stated that the five-year sentence “will run consecutive to any [burglary] parole violation” sentence imposed.
People v. Covington,
Covington’s presentenee report indicated that he was ultimately released in October 1982, but was unclear as to whether he was imprisoned for the burglary offense or the firearm offenses during the period between the December 1979 firearm arrest and his release. Covington objected to the presen-tence report, claiming that his return to prison was not a parole revocation for the burglary offense. See Objections to Presentenee Investigation Report at 4. At the sentencing hearing, Covington’s objection was made with more specificity:
if the parole was revoked, there was no continuation of this burglary sentence. In other words, he was not sentenced or was not committed to continue the sentence for the burglary case.... The parole was revoked and he was sent to prison on the [firearm offenses].
Sentеncing Tr. at 10. Despite these objections, the government did not introduce any evidence of any sentence ever being imposed on Covington for the burglary parole violation. 4 The district court found that Coving-ton was imprisoned for the burglary recom-mitment after June 1981, and sentenced Covington as a career offender.
This Court hаs held that “[o]nce a defendant objects to a factual allegation in the presentence report, the court must make (i) a finding as to the allegation, or (ii) a determination that no such finding is necessary because the matter controverted will not be taken into account in sentencing.”
United States v. Granados,
III.
Covington next claims that there was insufficient evidence that the substance he possessed was crack cocaine, rather than some other type of cocaine base, for purposes of his sentencing under U.S. Sentencing Guidelines Manual § 2D1.1. Covington does not challenge the finding that he possessed 882.17 grams of cocaine base. Indeed, at trial, lab evidence was introduced identifying the substance as cocaine base. Trial Tr. at 241. Instead, Covington suggests that a lab test or the testimony of а chemistry expert is required before a sentencing court may find by a preponderance of the evidence that the cocaine base is crack cocaine. We disagree.
We review the district court’s finding as to the “identity of drugs attributable
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to a defendant for clear error, reversing only if we are left with a definite and firm conviction that a mistake has been made.”
United States v. Maxwell,
IV.
Covington also challenges the sufficiency of the evidence supporting his conviction for conspiracy. He claims that Woods’s testimony was required to establish the existence of a conspiratorial agreement, an element of his offensе, and that because Woods was not credible, his testimony could not be believed by a rational jury. We disagree. “Both the Supreme Court and this Circuit have recognized the propriety of using and relying upon the testimony of a coconspirator to prove another’s connection to the conspiracy.”
United States v. Cruz,
V.
Next, Covington contends that the district court erroneously gave the jury a deliberate ignorance instruction. Covington reasons that the instruction undermined his defense strategy of attacking the credibility of his coconspirators, Woods and Williams. It appears that the deliberate ignorance instruction was meant to apply only to Pittman, whose defense was based on his having hаd no knowledge of the purchase. Nonetheless, the instruction was written to be generally applicable to each co-defendant.
5
We agree with Covington that the district court erred in giving the jury a generally applicable instruction when it was only relevant to the case against Pittman.
See United States v. Barnhart,
An unwarranted willful blindness instruction “creates a risk that the defendant will be convicted because he acted negligent
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ly or recklessly.”
6
Id.
An erroneous willful blindness instruction is harmless if it is “clear beyond a reasonable doubt that the jury would have returned a verdict of guilty.”
Id.
(quotation, citation, and alteration omitted). Hеre, the error was harmless because the evidence that Covington took part in the crack purchase was overwhelming.
See United States v. White,
VI.
Covington finally contends that the district court erred in denying his motion for a mistrial after Woods and Williams spoke briefly with each other when they were transported from the courthouse to the jailhouse, because the communication violated Federal Rule of Evidence 615. Rulе 615 provides that “[a]t the request of a party the court shall order witnesses excluded so that they cannot hear the testimony of other witnesses.” The district court has substantial discretion in deciding whether to grant a mistrial, and will be reversed only “if evidence of clear prejudice indicates the trial court’s ruling was an abuse of discretion.”
United States v. Kindle,
Notes
. We previously granted Covington leave to filе a supplemental pro se brief. Although it is not usually our practice to consider pro se filings when a party is represented by counsel,
see United States v. Blum,
. Thus, as a career offender with an offense level of 38, Covington’s sentencing range wаs 360 months to life, rather than 324 months to 405 months if he had not qualified.
. The firearm offenses would not qualify Coving-ton for career offender status because they are not considered to be “crimes of violence.” See U.S.S.G. § 4B1.2, comment, (n.2) (1995).
. The only evidence relevant to Covington’s state sentence that was provided to either this Court or the district court was а page of a docket sheet relating to Covington’s firearm convictions, provided by the government during oral argument before this Court. That docket sheet, which provides that his firearms sentence would be served consecutive to "any sentence imposed for” his burglary parole violation, is unhelpful in determining whether any sentence was actually imposed for the burglary parole revocation.
. The government argues that the jury instruction applied only to Pittman, and produced a copy of a jury instruction in its brief which referred specifically to Pittman. This "instruction” appears nowhere in the district court record, which includes only an instruction aрplicable to any defendant. See Instructions Given to Jury on Dec. 6, 1996, No. 19. We note our displeasure with the government’s failure to correctly represent the trial record in its brief or address the merits of Covington's claim.
. In this case, the risk of error was minimized because the instruction, itself, warned the jury that it could not convict for reckless or negligent conduct. See Instructions Given to Jury on Dec. 6, 1996, No. 19.