United States Court of Appeals
                             FOR THE EIGHTH CIRCUIT
                                   ___________

                                   No. 97-2604
                                   ___________

United States of America,               *
                                        *
            Appellee,                   *
                                        * Appeal from the United States
      v.                                * District Court for the
                                        * Western District of Missouri.
Charles A. Covington,                   *
                                        *
            Appellant.                  *
                                   ___________

                            Submitted: November 18, 1997
                                Filed:
                                    ___________

Before RICHARD S. ARNOLD, Chief Judge, and McMILLIAN and MAGILL,
      Circuit Judges.
                          __________

MAGILL, Circuit Judge.

    Charles 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 resentencing.
                          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, Jamescina 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, Covington
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 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 Covington was
questioned at the train station, he was released and was
not arrested until later.



                           -2-
    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.




                           -3-
    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 ignorance 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 two 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, 

, 646-47
(8th Cir. 1991).


      1
       We previously granted Covington leave to file 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, 

, 1443 n.2 (8th Cir.
1995), we have reviewed Covington’s pro se brief, and find that its claims lack merit
and do not warrant further discussion. See 8th Cir. R. 47B.

                                         -4-
    A defendant qualifies as a career 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




                           -5-
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 case, 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 and is not challenged as a basis for career offender
status.    The second conviction was for a burglary
committed by Covington 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
Illinois firearm offenses, and was again imprisoned.3 In
April 1980, an Illinois court sentenced Covington to five


      2
        Thus, as a career offender with an offense level of 38, Covington’s sentencing
range was 360 months to life, rather than 324 months to 405 months if he had not
qualified.
      3
      The firearm offenses would not qualify Covington 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).

                                         -6-
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, 

, 65 (Ill. App. Ct. 1981). The
record does not indicate whether a recommitment sentence
was ever imposed on Covington for his burglary parole
violation.    Covington was ultimately released from
Illinois custody in October 1982--within the fifteen-year
career offender period.




                           -7-
    Covington’s presentence 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 presentence report, claiming that his return to
prison was not a parole revocation for the burglary
offense.   See Objections to Presentence 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].

Sentencing 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 Covington was
imprisoned for the burglary recommitment after June 1981,
and sentenced Covington as a career offender.

    This Court has held that “[o]nce a defendant objects
to a factual allegation in the presentence report, the

      4
        The only evidence relevant to Covington's state sentence that was provided to
either this Court or the district court was a 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.

                                         -8-
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, 

, 771 (8th Cir. 1992) (quotation and citation
omitted). If the court chooses to make a finding as to
the factual allegation, “the government must introduce
evidence sufficient to




                         -9-
convince the Court by a preponderance of the evidence that
the fact in question exists.” 

(quotation
and citation omitted).    In this case, no evidence was
introduced to confirm that Covington was imprisoned for
burglary during the relevant period rather than for the
firearm offenses.     The conclusion of the presentence
report that Covington was imprisoned until October 1982
did not provide the court with the required preponderance
of evidence that Covington was imprisoned for burglary,
rather than for the firearm offenses, after his return to
custody in December 1979. Therefore, the district court
clearly erred when it found otherwise, and we remand for
resentencing.

                          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 832.17 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 a 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 to a defendant for clear
error, reversing only if we are left with a definite and

                           -10-
firm conviction that a mistake has been made.” United
States v. Maxwell, 

, 1397 (8th Cir. 1994).
The Sentencing Guidelines define crack as a “form of
cocaine base, usually prepared by processing cocaine
hydrochloride and sodium bicarbonate, and usually
appearing in a lumpy, rocklike form.” U.S.S.G. § 2D1.1(c)
(Note D) (1995).      It is well established that “the
identity of a controlled substance can . . . be proved by
circumstantial evidence and opinion testimony.” United
States v. Williams, 

, 1212 (8th Cir. 1992)
(finding the evidence sufficient to find guilt beyond a
reasonable doubt when “narcotics detective testified that
in his opinion the




                          -11-
government’s exhibits were crack cocaine”).          Here,
Detective Larry Cridlebaugh of the Kansas City, Missouri
Police Department testified at sentencing that it was his
opinion, based on his significant narcotics experience
consisting of hundreds of encounters with crack cocaine,
that the “tan rock-like substance” in Williams’s purse was
crack. Sentencing Tr. at 18-19. That evidence was more
than sufficient, and the district court did not clearly
err when it found the cocaine base to be crack cocaine.

                           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 offense, 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, 

,
396 (8th Cir. 1984). In this case, Woods’s testimony was
corroborated in many respects by the testimony of
Williams, and was also consistent with the series of
events witnessed by several Kansas City police officers
who testified at trial. In any event, the jury had the
opportunity to view Woods’s testimony and gauge his
credibility. Because “[i]t is not the function of the
appellate court to judge the credibility of a witness,”
United States v. Jackson, 

, 82 (8th Cir. 1992),
we accept the jury’s apparent conclusion that Woods’s
testimony was credible. After reviewing the evidence in

                           -12-
the light most favorable to the government, see 

review), we find sufficient evidence to
support Covington’s conviction.

                         V.

    Next, Covington contends that the district court
erroneously gave the jury a deliberate ignorance
instruction.   Covington reasons that the instruction
undermined his




                         -13-
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 had 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, 

, 652
(8th Cir. 1992) (deliberate ignorance instruction “should
not be given unless there is evidence to support the
inference that defendant was aware of a high probability
of the existence of the [drugs] and purposely contrived to
avoid learning [of the drugs] in order to have a defense
in the event of a subsequent prosecution” (quotation and
citation omitted)). We conclude, however, that the error
was harmless.

    An unwarranted willful blindness instruction “creates
a risk that the defendant will be convicted because he
acted negligently or recklessly.”6     

willful blindness instruction is harmless if it is “clear
beyond a reasonable doubt that the jury would have

      5
        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 applicable 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.
      6
       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.

                                          -14-
returned a verdict of guilty.” 

and alteration omitted).    Here, the error was harmless
because the evidence that Covington took part in the crack
purchase was overwhelming. See United States v. White,

, 371 (8th Cir. 1986). Additionally, the risk
of conviction for negligent or reckless behavior is
particularly low when, as here, there is a conviction for
conspiracy requiring




                           -15-
proof of a conspiratorial agreement. See United States v.
Hurley, 

, 9-10 (1st Cir. 1995) (willful blindness
instruction does not “dilute[] the express ‘intent’
requirement of the conspiracy count”). Additionally, any
reasonable juror would have understood the instruction to
apply only to Pittman, the only defendant to raise lack of
knowledge of the drugs as a defense. In fact, the jury
showed it understood the distinction by acquitting Pittman
while convicting Covington. Given “the circumstances of
the error,” 

, any error caused by
the instruction was harmless.

                           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.
Rule 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, 

, 276 (8th Cir. 1991).     Here, after Woods had
testified, he and Williams spoke briefly twice during a
single trip from the courthouse to the jailhouse. A U.S.
Marshal promptly instructed them not to discuss the case
and there has been no showing that the contact resulted in
less than candid testimony by Williams. See 

prejudice when “[t]here was no showing made that the

                           -16-
contact resulted in the tailoring of witness testimony .
. . or the development of less than candid testimony which
Rule 615 seeks to prevent”). Without more of a showing by
the defendant, we see no prejudice which would allow us to
conclude that the district court abused its discretion in
deciding not to grant a mistrial.




                           -17-
A true copy.


    Attest:


        CLERK, U.S. COURT OF APPEALS, EIGHTH CIRCUIT.




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