                                  from employing his own expert witness and he did not indicate any desire
                                  to do so. Therefore, we conclude Lagerev fails to demonstrate that the
                                  district court abused its discretion by allowing the State's expert rebuttal
                                  witness to testify. See Lopez v. State, 105 Nev. 68, 81, 769 P.2d 1276,
                                      1285 (1989).
                                                     Lagerev next contends that the district court erred by
                                  declining to allow him to call an untimely disclosed impeachment witness
                                  because impeachment witnesses need not be disclosed prior to trial and
                                  the witness' testimony directly supported his theory of defense. Lagerev
                                  informed the district court that the witness would impeach the testimony
                                  of a Highway Patrol officer. On appeal, Lagerev contends that the
                                  witness' testimony was admissible to impeach the testimony of a different
                                  witness. Because Lagerev did not offer the testimony for this purpose in
                                  the district court, we decline to consider this contention on appeal. See
                                  McCall v. State, 97 Nev. 514, 516, 634 P.2d 1210, 1212 (1981) ("Where
                                  evidence is not offered for a particular purpose at trial, an appellate court
                                  will not consider it for that purpose on appeal."). Moreover, even if the
                                  district court abused its discretion by concluding that the proffered
                                  witness could not testify in Lagerev's case-in-chief due to untimely
                                  disclosure, see NRS 174.234(1)(a)(1); Mitchell v. State, 124 Nev. 807, 819,
                                      192 P.3d 721, 729 (2008), any error was harmless because the witness'
                                  proffered testimony related only to a prior existing condition and was thus
                                  irrelevant to the determination of Lagerev's guilt. See NRS 484C.430(1);
                                  Williams v. State, 118 Nev. 536, 550-51, 50 P.3d 1116, 1125-26 (2002)
                                  (concluding that evidence of county's negligence was irrelevant in a trial
                                  for DUI causing death because any negligence was a preexisting condition
                                  that could not establish that defendant was not the proximate cause of the

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                accident); Etcheverry v. State, 107 Nev. 782, 784-85, 821 P.2d 350, 351-52
                (1991) (discussing proximate cause in context of DUI prosecution); see also
                Bostic v. State, 104 Nev. 367, 369-70, 760 P.2d 1241, 1243 (1988).
                            Lagerev also asserts that the prosecutor made an incorrect
                statement of law during closing argument and the district court erred by
                declining to dismiss the entire jury because it was "tainted" during the
                voir dire process. Lagerev does not support these contentions with any
                cogent argument or citation to authority and we therefore decline to
                address them. See Maresca v. State, 103 Nev. 669, 673, 748 P.2d 3, 6
                (1987). Accordingly, we
                            ORDER the judgment of conviction AFFIRMED.



                                                     A-4in
                                          Hardesty



                P-arraguirre U                            Cherry


                cc: Hon. Jessie Elizabeth Walsh, District Judge
                     Sandra L. Stewart
                     Attorney General/Carson City
                     Clark County District Attorney
                     Eighth District Court Clerk




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