UNPUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


UNITED STATES OF AMERICA,              
                 Plaintiff-Appellee,
                 v.                            No. 01-4433
ANDREW SCOTT ROCKWELL,
             Defendant-Appellant.
                                       
           Appeal from the United States District Court
    for the Northern District of West Virginia, at Martinsburg.
              W. Craig Broadwater, District Judge.
                            (CR-00-18)

                      Submitted: May 13, 2002

                      Decided: May 31, 2002

   Before WIDENER, WILLIAMS, and KING, Circuit Judges.



Affirmed by unpublished per curiam opinion.


                            COUNSEL

Brian Craig Manford, LAW OFFICE OF BRIAN CRAIG MAN-
FORD, Martinsburg, West Virginia, for Appellant. Thomas E. John-
ston, United States Attorney, Thomas O. Mucklow, Assistant United
States Attorney, Martinsburg, West Virginia, for Appellee.



Unpublished opinions are not binding precedent in this circuit. See
Local Rule 36(c).
2                     UNITED STATES v. ROCKWELL
                              OPINION

PER CURIAM:

  Andrew Scott Rockwell appeals his convictions and sentence for
conspiracy to possess with intent to distribute heroin and distribution
of heroin, in violation of 21 U.S.C.A. §§ 841, 846 (West 1999 &
Supp. 2001). For the reasons set forth below, we affirm.

   First, Rockwell contends that the district court erred in determining
the amount of heroin for which he could be held accountable. Consid-
ering the trial testimony of Leon Yancey, the testimony of other wit-
nesses, and the presentence report attributing certain relevant conduct
to Rockwell, we conclude that the district court did not clearly err in
determining the amount of heroin for which Rockwell could be held
accountable. See United States v. Randall, 

, 210 (4th Cir.
1999) (stating that this court reviews the district court’s determination
of the drug amount attributable to the defendant for clear error).

   Next, Rockwell asserts that the district court erred in denying his
motions for judgment of acquittal made pursuant to Federal Rule of
Criminal Procedure 29. Kimberly Wilt, Christine Arvin, Mark Arvin,
Clyde Morris, Jr., Wade Hensler, Yancey, J. R. Skelly, and Christo-
pher Ashton testified as to Rockwell’s heroin purchases and distribu-
tion of heroin to them and to others. It was within the sole province
of the jury to assess the credibility of these witnesses, see United
States v. Lowe, 

, 1142 (4th Cir. 1995), and the jury was
made aware through direct and cross examinations of the witnesses’
prior criminal records, plea and cooperation agreements, hopes for
some future benefit, and histories of substance abuse. Additionally,
the testimony of troopers who conducted visual and auditory surveil-
lance corroborated Rockwell’s sale to Wilt of six packets of heroin on
October 2, 1998, at the Arvins’ residence. Accordingly, we find sub-
stantial evidence supports the jury’s convictions of Rockwell of con-
spiracy to distribute and distribution of heroin, and the district court
did not err in denying Rockwell’s motions for judgment of acquittal.
See United States v. Burgos, 

, 862 (4th Cir. 1996) (en
banc).

   Rockwell next contends that the district court improperly admon-
ished Mark Arvin to testify truthfully, which had a chilling effect on
                      UNITED STATES v. ROCKWELL                        3
his testimony and deprived Rockwell of a fair trial. During direct
examination, Arvin expressed poor recollection of events involving
himself, Rockwell, and Wilt. This prompted the district court, during
a break outside the presence of the jury, to urge Arvin "to tell the
truth," be "up front," and state when he could not remember. (J.A. at
235.) We find the district court’s comments simply fulfilled its obli-
gation to control the interrogation of witnesses and presentation of
evidence so as to promote the ascertainment of truth and that the com-
ments were neither improper nor prejudicial. See Fed. R. Evid.
611(a), 614(b); Milanovich v. United States, 

, 721 (4th
Cir. 1960), aff’d in part and rev’d in part on other grounds, 

 (1961).

   Next, Rockwell contends that the district court committed prejudi-
cial error by not taking judicial notice of the fact that Trooper J. L.
Hudson was unavailable because she planned to invoke her Fifth
Amendment right against self-incrimination if called to testify.* The
district court permitted Rockwell to introduce Trooper Hudson’s
statement as an unavailable witness, but it declined to advise the jury
the reason for her unavailability was her invocation of her Fifth
Amendment right. Because the balancing required by Federal Rule of
Evidence 403 indicates that the potential prejudice substantially out-
weighs the probative value of the evidence, we hold that the district
court did not abuse its discretion in excluding the evidence. See Fed.
R. Evid. 201 403, United States v. Hassan El, 

, 731 (4th
Cir. 1993).

   Finally, we conclude that the district court did not abuse its discre-
tion in excluding from evidence as irrelevant portions of an FBI
report of a chemist, Todd McDaniel. The excluded evidence consisted
primarily of statements by McDaniel detailing misconduct that took
place during work hours in the West Virginia Crime Laboratory. As

   *Because the West Virginia State Police Laboratory was temporarily
closed following an investigation by the FBI for inconsistencies in
reporting and drug analyses, the Government had the controlled sub-
stances at issue retested by another laboratory. Trooper Hudson was the
forensic chemist who originally analyzed the drugs in question at the
West Virginia State Police Laboratory.
4                    UNITED STATES v. ROCKWELL
the district court concluded, any probative value of the excluded evi-
dence was outweighed by its prejudicial impact.

   We have reviewed the record and the district court’s opinion and
find no reversible error. Accordingly, we affirm Rockwell’s convic-
tions and sentence. We dispense with oral argument because the facts
and legal contentions are adequately presented in the materials before
the court and argument would not aid the decisional process.

                                                         AFFIRMED