UNPUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


UNITED STATES OF AMERICA,              
                 Plaintiff-Appellee,
                 v.                              No. 02-4797
GREGORY BUTLER,
             Defendant-Appellant.
                                       
           Appeal from the United States District Court
            for the District of Maryland, at Greenbelt.
             Alexander Williams, Jr., District Judge.
                         (CR-01-161-AW)

                      Submitted: March 10, 2003

                       Decided: April 1, 2003

     Before WILLIAMS and MICHAEL, Circuit Judges, and
              HAMILTON, Senior Circuit Judge.



Affirmed by unpublished per curiam opinion.


                             COUNSEL

Fred Warren Bennett, Booth Marcus Ripke, BENNETT &
NATHANS, L.L.P., Greenbelt, Maryland, for Appellant. Thomas M.
DiBiagio, United States Attorney, James M. Trusty, Assistant United
States Attorney, Stephanie A. Gallagher, Assistant United States
Attorney, Greenbelt, Maryland, for Appellee.
2                      UNITED STATES v. BUTLER
Unpublished opinions are not binding precedent in this circuit. See
Local Rule 36(c).


                               OPINION

PER CURIAM:

   Gregory Butler appeals his conviction and sixty-three month sen-
tence following a jury trial on charges of participating in a conspiracy
to distribute marijuana. See 21 U.S.C. § 846 (2000). Butler challenges
three separate evidentiary rulings by the district court as individually
and cumulatively prejudicial. For the following reasons, we affirm.

   This Court reviews a district court’s decision concerning the
admissibility of evidence for an abuse of discretion and will not find
an abuse unless a decision was "arbitrary and irrational." United
States v. Weaver, 

, 313 (4th Cir.), cert. denied, 

 (2002). The district court is afforded wide discretion in "deter-
mining whether evidence is unduly prejudicial." United States v. Ara-
mony, 

, 1377 (4th Cir. 1996).

    Butler’s first challenge, concerning the testimony of Dwayne McCal-
lum1 and Special Agent David Buckel of the Drug Enforcement
Agency, is unpersuasive. Butler challenges their testimony regarding
a post-conspiracy drug sting in which McCallum introduced Agent
Buckel to his suppliers in the conspiracy as "Greg Butler" as prejudi-
cial. However, the prosecution is entitled to introduce evidence of
uncharged criminal conduct to the extent it is probative; e.g., "where
it ‘furnishes part of the context of the crime.’" United States v. Mark,

, 448 (4th Cir. 1991). Testimony from Buckel and
McCallum provided evidence of Butler’s awareness of the conspiracy
and that it was supplied through McCallum’s connections, who
acknowledged his name and thus were inferentially aware of his par-
ticipation in the conspiracy. Further, based on the district court’s cura-
    1
   Although Butler’s brief refers to McCallum as "McCullam," because
the trial transcript identifies the witness as McCallum, we adopt that
spelling.
                        UNITED STATES v. BUTLER                         3
tive instruction and because Fed. R. Evid. 608(b) "should not be read
so broadly as to disallow the presentation of extrinsic evidence that
is probative of a material issue in a case," United States v. Smith
Grading & Paving, Inc., 

, 531 (4th Cir. 1985), we find
no error in the admission of this testimony.

   We find Butler’s challenge to Agent Buckel’s testimony on cross-
examination as impermissible vouching to be specious. While the
United States may not vouch for the credibility or trustworthiness of
one of its witnesses, or elicit testimony to that effect, United States
v. Lewis, 

, 1088-89 (4th Cir. 1993), Buckel did not opine
as to McCallum’s credibility, and the United States did not offer the
testimony. See United States v. Sanchez, 

, 198 (4th Cir.
1997). Furthermore, even if the statement was improper, the fact that
Butler’s counsel invited the error forecloses review. See Joseph v.
Angelone, 

, 329 (4th Cir. 1999) (applying invited error
doctrine to statements elicited during cross-examination).

   Finally, we find no abuse of discretion in the district court’s deci-
sion to limit Butler’s cross-examination. See United States v. Cropp,

, 358 (4th Cir. 1997) (providing standard of review). A
defendant has a right under the Sixth Amendment to cross-examine
witnesses who are cooperating with the United States about potential
sources of bias. Id. However, the court retains the discretion to place
reasonable limits on cross-examination based on concerns about,
among other things, harassment, prejudice, confusion, repetition, or
relevance. Delware v. Van Arsdall, 

, 678-79 (1986). But-
ler’s counsel had already obtained McCallum’s admission to a past
affiliation with a motorcycle gang, and his proffer failed to suggest
either that McCallum was lying about no longer being a member of
the gang or that McCallum, as a past or current member, would be
likely to falsely accuse Butler. In light of that proffer, the district
court properly prohibited further questioning regarding this wholly
unsupported theory of bias.

  Accordingly, because we find no error in any of the district court’s
decisions,2 we affirm Butler’s conviction. Further, as we have dis-
  2
   To the extent Butler alleges cumulative error, a cumulative error anal-
ysis applies only when there are two or more actual errors; it does not
apply to the cumulative effect of non-errors. See Moore v. Reynolds, 

, 1113 (10th Cir. 1998).
4                     UNITED STATES v. BUTLER
pensed 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, we therefore deny Butler’s
motion for oral argument.

                                                        AFFIRMED