A trial court's findings in a criminal case have the effect of a jury verdict, and a conviction in a bench trial will be sustained if the properly admitted trial evidence, viewed and construed most favorably to the State, is sufficient to support the conviction. State v. Meers, 257 Neb. 398, 598 N.W.2d 435 (1999); State v. Christner, 251 Neb. 549, 557 N.W.2d 707 (1997), overruled on other grounds, State v. Anderson, 258 Neb. 627, 605 N.W.2d 124 (2000).
The admissibility of evidence is reviewed for an abuse of discretion where the Nebraska Evidence Rules commit the evidentiary question at issue to the discretion of the trial court. Carpenter v. Cullan, 254 Neb. 925, 581 N.W.2d 72 (1998); State v. Earl, 252 Neb. 127, 560 N.W.2d 491 (1997).
The determination whether an expert's testimony will assist the trier of fact involves the discretion of the court, whose ruling on admissibility of an expert's testimony will be upheld on appeal in the absence of an abuse of discretion. State v. Reynolds, 235 Neb. 662, 457 N.W.2d 405 (1990). See Cohen v. Papio-Missouri River NRD, 8 Neb. App. 807, 602 N.W.2d 49 (1999).
A judicial abuse of discretion exists when a judge, within the effective limits of authorized judicial power, elects to act or refrain from action, but the selected option results in a decision which is untenable and unfairly deprives a litigant of a substantial right or a just result in matters submitted for disposition through the judicial system. State v. Reynolds, supra; Cohen v. Papio-Missouri River NRD, supra.
The decision whether to grant a motion for mistrial is within the discretion of the trial court and will be upheld on appeal absent a showing of abuse of discretion. State v. Bjorklund, 258 Neb. 432, 604 N.W.2d 169 (2000); State v. Kirksey, 254 Neb. 162, 575 N.W.2d 377 (1998).
A mistrial is properly granted when an event occurs during the course of a trial which is of such a nature that its damaging effect cannot be removed by proper admonition or instruction to the jury and thus would result in preventing a fair trial. Bjorklund, supra; Kirksey, supra.
Before it is necessary to grant a mistrial due to prosecutorial misconduct, a defendant must show that a substantial miscarriage of justice occurred. Bjorklund, supra.
The impact of any comment made at trial depends on the atmosphere at trial. the trial judge is in a better position to measure the impact a comment has on a jury, and his or her decision will not be overturned unless clearly erroneous. State v. Trackwell, 244 Neb. 925, 509 N.W.2d 638 (1994); State v. Swillie, 240 Neb. 740, 484 N.W.2d 93 (1992).