specially concurring.
While I agree with the majority that the testimony of the victim’s sister was properly admitted, I cannot agree that the testimony establishes a motive for the crime, as suggested by the majority. Such testimony is admissible to establish a continuing plan to sexually assault family members and to establish a method characteristically employed. Secondly, the testimony was relevant in that it corroborated the credibility of the victim. People v. Covert, 249 Cal.App.2d 81, 57 Cal.Rptr. 220, hrg. denied (1967); People v. Fritts, 72 Cal.App.3d 319, 140 Cal.Rptr. 94, hrg. denied (1977); State v. Thomas, 110 Ariz. 106, 515 P.2d 851, reh. denied (1973).
Rule 404(b), W.R.E., provides that evidence of other crimes may be admitted to prove “motive, opportunity, intent, preparation, plan, knowledge, identity, or absence of mistake or accident.” In the instant case the following evidence was introduced:
(1) Both girls were the defendant’s stepdaughters.
*1051(2) Both girls were minors when the defendant assaulted them: the victim was nine years old and her sister was 11 and 12 years old.
(3) Both girls were assaulted in a bedroom.
(4) Both girls were told to remove their clothing and after they refused the defendant took off their clothes.
(5) Defendant first fondled the victims’ genitalia with his finger and then attempted to force his penis into them. He succeeded in penetrating the nine-year-old.
I find that the testimony of both victims shows a common plan and method of operation and therefore is admissible as an exception under Rule 404(b), supra.
Furthermore, when the defendant took the stand he accused the victim of fabricating the story because he and the victim’s mother were having marital difficulties. The defendant’s plea of innocence and his testimony concerning the alleged frame-up challenged the credibility of the complaining witness. The testimony of the victim’s sister during rebuttal was therefore relevant. People v. Covert, supra, 249 Cal.App.2d 81, 57 Cal.Rptr. at 224-225.