The admissibility of evidence regarding prior bad acts is controlled by 27-404 provides, in pertinent part: (1) Evidence of a person's character or a trait of his or her character is not admissible for the purpose of proving that he or she acted in conformity therewith on a particular occasion, except: (a) Evidence of a pertinent trait of his or her character offered by an accused, or by the prosecution to rebut the same; (2) Evidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show that he or she acted in conformity therewith. It may, however, be admissible for other purposes, such as proof of motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident. (3) When such evidence is admissible pursuant to this section, in criminal cases evidence of other crimes, wrongs, or acts of the accused may be offered in evidence by the prosecution if the prosecution proves to the court by clear and convincing evidence that the accused committed the crime, wrong, or act. Such proof shall first be made outside the presence of any jury. Section 27-404 is patterned after rule 404 of the Federal Rules of Evidence, and accordingly, judicial construction of that federal counterpart is relevant. See, e.g., State v. Johnson, 220 Neb. 392, 370 N.W.2d 136 (1985) (construing Nebraska's hearsay rule by reference to federal rule), abrogated on other grounds, State v. Morris, 251 Neb. 23, 554 N.W.2d 627 (1996). The federal rules clearly envision that the prosecution is entitled to enter prior bad acts evidence once the defendant has "opened the door" by putting his character at issue. See, generally, 2 Joseph M. McLaughlin, Weinstein's Federal Evidence 405.03(1)(d) at 405-10-11 (2d ed. 1997) ("once the defendant has opened the door to a discussion of his or her character by calling character witnesses under Rule 404(a)(1), the prosecution may both cross-examine defendant's witnesses and call its own witnesses in rebuttal"). This is the approach under Nebraska's rule as well. While Rule 404 generally assumes that the adverse prejudicial effect of character evidence substantially outweighs any probative value of such evidence, Rule 404(1)(a) makes an exception to this Rule available to the accused. Consequently, the accused in a criminal case may put in issue his or her character for a relevant pertinent trait. . . . of course, the threat of opening the door for the prosecutor to inquire during cross-examination into the accused's prior bad acts which would have otherwise been inadmissible, serves as a substantial deterrent to an accused offering good character evidence under Rule 404(1)(a). R. Collin Mangrum, Nebraska's Evidentiary Rules on Relevancy, 29 Creighton L. Rev. 119, 160-61 (1995). To preserve a claimed error in the admission of evidence, a litigant must make a timely objection which specifies the ground of the objection to the offered evidence. State v. Juhl, 234 Neb. 33, 449 N.W.2d 202 (1989); State v. Armstrong, 1 Neb. App. 21, 485 N.W.2d 341 (1992). "'"If when inadmissible evidence is offered(,) the party against whom such evidence is offered consents to its introduction, or fails to object, or to insist upon a ruling on an objection to the introduction of such evidence, and otherwise fails to raise the question as to its admissibility, he is considered to have waived whatever objection he may have had thereto, and the evidence is in the record for consideration the same as other evidence."'" In re Interest of L.H. et al., 241 Neb. 232, 243, 487 N.W.2d 279, 288 (1992) Compare State v. Blair, 227 Neb. 742, 419 N.W.2d 868 (1988) (in order to preserve objection to admission of evidence under 27-404(2), objection must be made at time evidence is offered).