[*P11] We review a Sixth Amendment constitutional speedy trial claim de novo. People v. Flores, 2009 Guam 22 ¶ 9; People v. Mendiola, 1999 Guam 8 ¶ 22. By contrast, "[a] trial court's denial of a defendant's motion to dismiss on statutory speedy trial grounds is reviewed for an abuse of discretion."

The Sixth Amendment of the United States Constitution guarantees that "[i]n all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial . . . ." U.S. Const. amend. VI. The substance of the speedy trial right is defined through analysis of the peculiar facts and circumstances of each case. People v. Flores, 2009 Guam 22 ¶ 41. In evaluating a claimed speedy trial violation, this court employs the four-part balancing test set forth in Barker v. Wingo, 407 U.S. 514, 530, 92 S. Ct. 2182, 33 L. Ed. 2d 101 (1972).

We review a constitutional speedy trial claim de novo. People v. Flores, 2009 Guam 22 ¶ 9 (citing People v. Mendiola, 1999 Guam 8 ¶ 22). IV. ANALYSIS

We review the denial of a motion for mistrial for an abuse of discretion. See People v. Flores, 2009 Guam 22 ¶ 9 (citing Caston v. State, 823 So. 2d 473, 492 (Miss. 2002)).

An alleged violation of the Sixth Amendment is reviewed de novo. United States v. Yazzie, 743 F.3d 1278, 1288 (9th Cir. 2014), cert. denied, 135 S. Ct. 227, 190 L. Ed. 2d 172 (2014) (citing United States v. Ivester, 316 F.3d 955, 958 (9th Cir. 2003)); see also People v. Flores, 2009 Guam 22 P 9 (citing People v. Mendiola, 1999 Guam 8 P 22) (reviewing a Sixth Amendment speedy trial claim de novo). IV. ANALYSIS

When reviewing a constitutional violation, such as a comment on a defendant's invocation of his right to remain silent, the standard of review is harmless error, with a higher burden of proof than for non-constitutional errors. People v. Flores, 2009 Guam 22 ¶ 112 ("The test for harmless error is whether it appears beyond a reasonable doubt that the error complained of did not contribute to the verdict obtained." (quoting Neder v. United States, 527 U.S. 1, 15, 119 S. Ct. 1827, 144 L. Ed. 2d 35 (1999)) (internal quotation marks omitted)).

"[C]laims of insufficient evidence are matters of law that are reviewed de novo." People v. Flores, 2009 Guam 22 ¶ 10 (citing People v. Maysho, 2005 Guam 4 ¶ 6; United States v. Shipsey, 363 F.3d 962, 971 n.8 (9th Cir. 2004)). "'In reviewing the sufficiency of the evidence to support a criminal conviction,' this court inquires as to 'whether the evidence in the record could reasonably support a finding of guilty beyond a reasonable doubt."

Questions regarding the propriety of a rebuttal witness are reviewed for an abuse of discretion. See People v. Flores, 2009 Guam 22 ¶ 117. A prior inconsistent statement may be admitted for impeachment purposes even when they are oral and unsworn.

"The trial court's denial of a defendant's motion for a new trial is reviewed for an abuse of discretion." People v. Leslie, 2011 Guam 23 ¶ 12 (citing People v. Flores, 2009 Guam 22 ¶ 9).IV. ANALYSIS

We have stated that we review for an abuse of discretion the denial of a motion to dismiss alleging a violation of the statutory speedy trial periods set forth in 8 GCA § 80.60. People v. Flores, 2009 Guam 22 ¶ 9. We have not previously set forth a standard of review for the grant or denial of a motion to dismiss alleging unnecessary delay in bringing a defendant to trial, in violation of 8 GCA § 80.70(b).