In State v. Catsam, 148 Vt. 366, 534 A.2d 184 (1987), the Court found inadmissible an expert's opinion that child victims of sexual abuse do not make up stories of the abuse. The evidence was offered as part of the expert's explanation of the typical behavior of victims. The Court concluded that the expert testimony was tantamount to an expert opinion that the victim was telling the truth and that it invaded the proper role of the jury. The Court affirmed the admission of evidence of defendant's prior sexual assaults on the victim, which occurred on six occasions over the two years prior to the charged incident. The holding was: Evidence that the defendant previously molested the victim, and threatened her with harm if she were to reveal the incident, gives rise to the legitimate inference that because of the manner in which the prior sexual acts were perpetrated, the prior acts and the charged crime were part of a concerted scheme or plan of molestation. (Id. at 381, 534 A.2d at 194.) In announcing this holding, the Court acknowledged that "admitting evidence of prior sexual acts to prove a plan comes perilously close to the prohibited practice of admitting evidence of the defendant's character to prove he acted in conformity therewith in committing the crime charged." Id. Thus the Court emphasized: "in order to ensure the principled application of the rule, trial courts must find, at a minimum, a clear inference of the existence of a plan from the prior acts. At least two factors are crucial considerations in making this determination: similarity between the prior acts and the crime charged and proximity in time. . . . Other factors may also be considered, but the controlling consideration is whether the evidence tends to establish a scheme or plan of sexual molestation." (Id. at 382, 534 A.2d at 194.)