                application of the law to those facts de novo.    Lader v. Warden, 121 Nev.
                682, 686, 120 P.3d 1164, 1166 (2005).
                            First, appellant argues that trial counsel was ineffective for
                failing to hire a private investigator to assist with pretrial investigation
                and for failing to adequately investigate. Appellant contends that
                counsel's failure to investigate prevented him from developing defense
                witnesses and resulted in counsel's decision to downplay the gang aspect.
                Appellant has failed to demonstrate deficiency or prejudice. Counsel
                testified at the evidentiary hearing that he interviewed 15 to 20 witnesses
                and that he made a strategic decision to minimize appellant's gang
                affiliation at trial. While appellant asserts that counsel's testimony was
                unbelievable, matters of credibility are left to the district court.   See State
                v. Rincon, 122 Nev. 1170, 1177, 147 P.3d 233, 238 (2006). Appellant fails
                to identify any witnesses that counsel should •have investigated.'
                Furthermore, while appellant contends that he was prejudiced by
                counsel's decision not to present evidence of gang involvement, he fails to
                explain how further investigation by counsel would have altered counsel's
                strategy at trial and thus have affected the outcome of the proceedings.
                We therefore conclude that the district court did not err in denying this
                claim.


                       "In his reply brief, appellant argues that his trial counsel was
                ineffective for failing to interview J. Sandoval. However, appellant did not
                raise this issue in his opening brief and, because a reply brief is limited to
                countering any matter set forth in the answering brief, we decline to
                consider this claim. See NRAP 28(c); see also Bongiovi v. Sullivan, 122
                Nev. 556, 569 n.5, 138 P.3d 433, 443 n.5 (2006); Elvik v. State, 114 Nev.
                883, 888 & n.6, 965 P.2d 281, 284 & n.6 (1998).



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                                  Second, appellant argues that trial counsel was ineffective for
                      failing to file any pretrial motions and for failing to request criminal
                      histories on the State's key witnesses. Appellant has failed to
                      demonstrate prejudice. Appellant does not identify any pretrial motions
                      and presents no cogent argument as to counsel's failure to file any
                      motions. See Maresca v. State, 103 Nev. 669, 673, 748 P.2d 3, 6 (1987).
                      While he contends that counsel should have requested criminal histories
                      of the witnesses, he does not allege what the criminal histories would have
                      revealed or how they would have altered the outcome at trial.     See Molina
                      v. State, 120 Nev. 185, 192, 87 P.3d 533, 538 (2004). We therefore
                      conclude that the district court did not err in denying these claims.
                                  Third, appellant argues that trial counsel was ineffective for
                      allowing the admission of appellant's medical records in an "evidentiary
                      vacuum," for failing to investigate an injury to appellant's right arm that
                      could have rendered appellant incapable of committing the murder, and
                      for failing to investigate the photographic line-up. We decline to consider
                      these claims because appellant did not raise them below in his petition or
                      supplemental petition.    See Davis v. State, 107 Nev. 600, 606, 817 P.2d
                      1169, 1173 (1991), overruled on other grounds by Means v. State, 120 Nev.
                      1001, 1012-13, 103 P.3d 25, 33 (2004).
                                  Fourth, appellant argues that trial counsel was ineffective for
                      failing to investigate the need for an expert to counter the State's expert
                      witness testimony regarding the gang enhancement. Appellant argued
                      below that counsel was ineffective for failing to attack the State's gang
                      expert. Because the argument on appeal is not the same as that raised
                      below, we decline to consider it. See Ford v. Warden, 111 Nev. 872, 884,



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                 901 P.2d 123, 130 (1995) (stating that an appellant "cannot change [his]
                 theory underlying an assignment of error on appeal").
                             Fifth, appellant argues that he is entitled to post-conviction
                 relief due to the cumulative errors of counsel. He names as errors
                 counsel's failure to adequately prepare appellant to testify, failure to
                 prepare or advocate any defense, failure to consult or retain a crime scene
                 expert or reconstructionist about blood spatters, and failure to object to
                 evidence of gang affiliation, prior bad acts, and hearsay testimony.
                 Appellant failed to raise any of these claims of error below, and thus we
                 decline to consider his claim of cumulative error.   See Davis, 107 Nev. at
                 606, 817 P.2d at 1173.
                             Next, appellant claims that the district court erred in denying
                 his claims as bare and naked after granting an evidentiary hearing on his
                 petition. He contends that being granted an evidentiary hearing means
                 that he provided specific factual allegations in his petition. We conclude
                 that appellant misunderstands the law. While a petitioner is entitled to
                 an evidentiary hearing if he raises claims that are not belied by the record
                 and entitle him to relief, he has the burden of proving his claims at the
                 hearing. See Hargrove v. State, 100 Nev. 498, 502-03, 686 P.2d 222, 225
                 (1984). Moreover, the district court's grant of an evidentiary hearing on a
                 petition does not necessitate a finding that every claim raised in the
                 petition was supported by specific factual allegations, particularly where,
                 as here, numerous claims were raised. We therefore conclude that this
                 argument does not entitle appellant to relief.
                             Finally, appellant argues that portions of the district court's
                 findings are not entitled to deference on appeal because the district court
                 did not make a preliminary finding that trial counsel made a sufficient

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                 inquiry into the facts of the case. Appellant claims that this finding was
                 necessary for the district court to determine whether trial counsel's
                 decisions were reasonable. Appellant has failed to demonstrate that the
                 district court erred in denying any of his claims or that the district court's
                 order was insufficient to allow this court to properly review appellant's
                 claims. We therefore conclude that this argument does not entitle
                 appellant to relief. Accordingly, we
                             ORDER the judgment of the district court AFFIRMED.




                                                                  teo                 J.
                                                     Hardesty


                                                                                      J.
                                                     Douglas




                 cc:   Hon. Elizabeth Goff Gonzalez, District Judge
                       Michael H. Schwarz
                       Attorney General/Carson City
                       Clark County District Attorney
                       Eighth District Court Clerk




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