Defendant appeals his conviction for sodomy in the first degree. ORS 163.405. He argues that the court erred in admitting testimony describing his alleged abuse of the victim’s sister. We agree and reverse.
The grand jury indicted defendant for engaging in deviate sexual intercourse with the nine-year-old daughter of his then fiancee, between March 18 and June 18, 1983. In March, 1983, the victim, her mother, her three-year-old sister, her newborn brother and defendant moved into an apartment. The victim’s mother and defendant were the parents of the victim’s brother. Their relationship deteriorated after the child was born, and on June 18, 1983, defendant moved out of the apartment at the mother’s request.
The victim testified at trial that, while defendant was living at the apartment, he had forced her to engage in sexual intercourse and oral and anal sodomy. She said that defendant had threatened that she would never see her mother again if she told anyone. On cross-examination, she admitted that, in a September, 1983, interview with Children’s Services Division (CSD) caseworker Routzahn she had denied that defendant had sexually abused her.
Before beginning redirect examination, the district attorney advised the court, outside the jury’s presence, that he intended to question the victim concerning defendant’s sexual abuse of her sister. He argued that the evidence was relevant, first, to complete the picture of the crime by explaining to the jury what prompted CSD, the police and the victim’s mother and grandmother to ask the victim whether defendant had abused her and, second, to explain why the victim ultimately reported that defendant had abused her after she had denied it initially. The court decided that the prejudicial effect on the jury outweighed the state’s need to complete the picture of the crime but admitted the evidence, over defendant’s objection, on the ground that the state’s need to explain the victim’s inconsistent statements outweighed the prejudice to defendant.
The victim testified before the jury that she had initially denied any sexual abuse by defendant, because she feared that, as he had threatened, she would not see her *308mother again if she accused him of abusing her. She also stated that, when Routzahn interviewed her, defendant had moved and his sexual abuse had ceased. After that interview she learned that defendant was seeking to gain custody of her brother. She said that she then decided to tell her mother that defendant had abused her, because she feared that, because defendant had abused both her and her sister, he would also abuse her brother. During further questioning by the district attorney concerning defendant’s abuse of her sister, she testified that she had seen her sister holding defendant’s penis one evening in the bedroom she then shared with her. She further stated that her mother had told her that her sister’s “bottom” was bloody and “all torn up” and that her sister had said “Daddy doctor” was responsible, apparently referring to defendant. The court cautioned the jury that it should consider the evidence concerning what the mother told the victim “only with the limited purpose of what may have been on the mind of the youngster and not for any purpose as to the truth that something else happened, or whether it might bear on the guiltiness of the Defendant, but only on the mind of the witness.” The victim then testified that what had happened to her and her sister would make her feel “bad” if defendant and her brother were together.
During his case-in-chief, defendant introduced evidence to support his theory that, after the victim’s mother learned in December, 1983, that he was seeking visitation rights or custody of his son, she had persuaded the victim to fabricate the story of abuse so that a court would not grant him visitation rights or custody. On rebuttal, the state offered Routzahn’s testimony that, in September, 1983, the victim’s sister had complained to her of defendant’s abuse and that she had then told the mother that in her opinion defendant had raped and sodomized the victim’s sister. The state’s theory of relevance, which the- court accepted, was that, if the victim’s mother knew several months before defendant sought visitation that defendant had abused the victim’s sister, she would have had no reason to ask the victim to fabricate allegations against defendant — the documented incident of abuse would be sufficient for her to defeat defendant’s attempt to gain custody and visitation.
Defendant assigns as error that the court admitted the victim’s and Routzahn’s testimony concerning the abuse *309of the victim’s sister. We hold that the court committed reversible error in admitting Routzahn’s testimony.1
Evidence of other crimes or bad acts committed by a defendant is generally not admissible to prove commission of a subsequent crime. OEC 404(3);2 Youngblood v. Sullivan, 52 Or App 173, 176, 628 P2d 400, rev den 291 Or 368 (1981). If, however, the court finds that the evidence is relevant to an issue which the state is entitled to prove, then it must weigh the probative value of that evidence against its prejudicial impact. Because evidence of previous sex crimes may have a highly inflammatory effect on a jury, the general rule against admission of prior bad act evidence should be applied strictly in sex abuse cases. See State v. Pace, 187 Or 498, 212 P2d 755 (1949); State v. Collins, 73 Or App 216, 222, 698 P2d 969 (1985).
The state argues that Routzahn’s testimony was admissible to rebut defendant’s conspiracy charge. Although we agree that under this theory the state was entitled to offer evidence that in September, 1983, the sister had complained to Routzahn and that the mother was aware at that time of the complaint, only evidence of the facts that the complaint had been made and that the mother was aware at that time of the complaint were relevant. The details of defendant’s alleged abuse of the sister were not. See State v. Bovee, 75 Or App 544, 548 n 4, 706 P2d 1005 (1985). Routzahn’s testimony concerning the details of the abuse of the sister was both extensive and *310graphic.3 It was not probative of any fact at issue and was highly prejudicial.
The indictment charged defendant with abusing the victim; it did not charge him with abusing the victim’s sister. The detailed evidence in support of the uncharged offense was undoubtedly highly offensive to the jury and was very likely to produce a sense of outrage which seriously affected the jury’s ability to deliberate dispassionately. Indeed, the evidence on the uncharged offense was probably more offensive than any involving the charged crime. The jury in effect was invited to convict defendant of the charge in the indictment because he had also committed the additional offense that was not charged. That is precisely what the rule against other crimes evidence is designed to prevent. Although the fact of the sister’s complaint was admissible, the admission of Rotzahn’s testimony concerning the details of the abuse requires reversal. See State v. Harris, supra n 1, 78 Or App at 492.4
*311Because the issue of the victim’s testimony is likely to come up again on retrial, we discuss it briefly. The state argues that evidence of the victim’s knowledge of defendant’s abuse of her sister was relevant to rebut defendant’s attack on her credibility, because it explained why she reported his abuse of her after telling Routzahn that he had not abused her. The victim testified that initially she had denied that she had been abused, because defendant was no longer living with her and her mother, but came forward when she learned that he was seeking custody of her brother. Because her concern for her brother was based both on defendant’s abuse of her and on her knowledge of his abuse of her sister, the state argues, the evidence of her knowledge of defendant’s abuse of her sister was admissible.
We agree that the victim’s testimony that she believed that defendant had abused her sister would be relevant to rebut defendant’s attack on her credibility. Under this theory, however, evidence of the details of the abuse would not be admissible.5 Moreover, the probative value of the evidence must be weighed against the prejudicial impact and the testimony limited accordingly.6
Reversed and remanded for a new trial.