Opinion
CHRISTIAN, J.Defendant John William Jackson was convicted of rape (Pen. Code, § 261, subd. 3) and forcible oral copulation (Pen. Code, § 288a, subd. (c)) after a trial by jury and was also found to have used a deadly weapon in the commission of the offenses (Pen. Code, § 12022, subd. (b)). He was subsequently found not to be a mentally disordered sex offender (MDSO) (Welf. & Inst. Code, § 6300 et seq.).
On appeal defendant asserts that prejudicial error occurred when the trial court admitted evidence that he had committed a prior offense, that the evidence was insufficient to support the convictions and the “use” finding, and that the finding that he was not an MDSO was not supported by the record. We reject these contentions.
On November 9, 1978, the victim was asleep in the front room of the Aries Massage Parlor when she was awakened because a towel had been placed over her face, impairing her breathing. She saw defendant standing over her holding an 18-inch pair of scissors which were normally kept in the medicine cabinet in the bathroom of the massage parlor. A brief struggle followed, and the victim smelled alcohol on defendant’s breath. In an effort to stall, she suggested to defendant that they would be more comfortable in the back room of the massage parlor. Upon arriving in the back room, defendant undressed the victim and forced her to perform oral copulation. After a brief conversation, defendant then had sexual intercourse with the victim. Upon returning to the front room, the victim made two phone calls after assuring defendant that she was not calling the police. Through signaling she conveyed to a friend that she needed help. Shortly thereafter, Officers *565Paul Tessier and Michael Loesch arrived at the massage parlor and arrested defendant. The officers found a footprint which matched the pattern on defendant’s shoes on the toilet lid in the bathroom, indicating that he had entered the premises through the bathroom window.
At trial a witness testified that in February of 1977 she had been awakened by defendant, who was holding a knife, and had been forced to perform two acts of oral copulation. There was evidence that defendant had entered through the bathroom of the apartment, that they had talked for a while, and that defendant appeared confused.
I
Defendant contends that prejudicial error occurred when the trial court admitted evidence of the February 1977 oral copulation. Prior to trial counsel for defendant informed the court that his trial theory would be that the victim in the present case had consented to the sexual acts. When the judge subsequently admitted evidence of the prior offenke, he explained that by trying to show that the victim consented, defendant had placed his intent at issue. Defendant now contends that the admission of the forced act of oral copulation in 1977 was not relevant because the lack of consent by that victim does not show a lack of consent in the present case.
As a general rule, evidence that a defendant committed other offenses is inadmissible if offered solely to prove his criminal disposition or propensity. (Evid. Code, § 1101, subd. (a); People v. Kelley (1967) 66 Cal.2d 232, 238 [57 Cal.Rptr. 363, 424 P.2d 947].) The primary purpose of this rule is to protect against misuse of uncharged acts, prejudicing the defendant in the minds of the jurors. (People v. Cramer (1967) 67 Cal.2d 126, 129 [60 Cal.Rptr. 230, 429 P.2d 582].) Nevertheless, “[i]t is settled that evidence of other crimes is ordinarily admissible where it tends to show guilty knowledge, motive, intent.. .. ” (People v. Kelley, supra, 66 Cal.2d at p. 239.) When prior offense evidence is relevant to prove some material fact at issue, other than the mere general disposition of the defendant to commit such offenses, it is generally admissible. (Evid. Code, § 1101, subd. (b).) The trial court, however, “may [in its discretion] exclude evidence if its probative value is substantially outweighed by the probability that its admission will.. .create substantial danger of undue prejudice.” (Evid. Code, § 352.) The court will be held to have abused its discretion if it admits evidence, the probative value of which is outweighed by its *566prejudicial effect. (People v. Haston (1968) 69 Cal.2d 233, 246 [70 Cal.Rptr. 419, 444 P.2d 91].)
Even if evidence of a prior crime is offered for the admissible purpose of proving intent, it should be excluded unless it is logically relevant to prove the defendant’s intent in the charged offense. (People v. Thompson (1980) 27 Cal.3d 303, 318-319 [165 Cal.Rptr. 289, 611 P.2d 883].) Evidence of a prior offense is logically relevant to prove the defendant’s intent if the prior offense was sufficiently similar in its commission to the charged offense to indicate that the defendant probably harbored the same intent in both instances. (Cf. People v. Thompson, supra, 27 Cal.3d at pp. 319-321 [insufficient similarity of offenses to invest the evidence of the prior offense with probative value substantial enough to outweigh prejudicial effect].) The admission of such evidence is not an abuse of discretion.
Additionally, in cases involving sex crimes, evidence of similar, nonremote prior sex offenses is admissible to corroborate the victim’s testimony on a material issue such as the intent of the defendant. (People v. Thomas (1978) 20 Cal.3d 457, 468-469 [143 Cal.Rptr. 215, 573 P.2d 433]; People v. Hunt (1977) 72 Cal.App.3d 190, 199-203 [139 Cal.Rptr. 675].) Such evidence is admissible because “by reason of the unique circumstances of privacy and seclusion surrounding the commission of most sex offenses the determination of witness credibility plays a central role.” (People v. Thomas, supra, 20 Cal.3d at p. 468.) Defendant’s trial theory, that the victim had consented to the sexual acts, was tantamount to a denial that he had intended to achieve oral copulation and sexual intercourse by force or intimidation. Evidence of prior offenses was thus admissible to establish defendant’s intent in the present offense by corroborating the victim’s testimony that she had not consented to the sex acts, so long as those prior offenses were not too remote and were similar to the offense charged. (See People v. Jackson (1980) 102 Cal.App.3d 620, 625 [162 Cal.Rptr. 574].) The court’s limiting instruction, that the evidence of the prior offense was admissible to prove intent, was appropriate to both theories of admissibility.
The present offense and the prior offense were close in time (one year and nine months apart) and shared several similar marks. In each case defendant entered the premises through the bathroom during early morning hours. Upon gaining entry, he armed himself with an instrument, found inside the building, which could be used for cutting or *567stabbing. In both instances he approached his victim by placing his hand over the victim’s mouth while holding the weapon in an attack position above the victim’s head. Defendant forced each victim to perform an act of oral copulation, then remained and engaged the victim in rather protracted conversation. Finally, it is noted that the victims in both cases were young women. There were an adequate number of common features in both cases to give rise to a reasonable inference that defendant harbored the same intent in both instances. Therefore the trial court could reasonably determine that the probative value of the prior offense outweighed its prejudicial effect. The court did not abuse its discretion when it admitted evidence of the prior offense.
II
Defendant next contends that the evidence was insufficient to support the jury’s verdict. As noted in People v. Hillery (1965) 62 Cal.2d 692, 702 [44 Cal.Rptr. 30, 401 P.2d 382], cert. den. 386 U.S. 938 [17 L.Ed.2d 810, 87 S.Ct. 958.], reh. den. 386 U.S. 1000 [18 L.Ed.2d 355, 87 S.Ct. 1310], “‘[t]he test on appeal is whether there is substantial evidence to support the conclusion of the trier of fact. It is not whether guilt is established beyond a reasonable doubt....’”
Defendant argues that the entire case against him rests upon the testimony of the victim which was so “thoroughly impeached by her pri- or inconsistent statements as to render it unbelievable,” and that significant portions of her testimony were innately implausible and not corroborated by other witnesses.
The victim’s testimony was certainly a central part of the prosecution’s case, but it was not the only evidence. The testimony of the prior victim, as well as that of Officers Tessier and Loesch, served to corroborate the victim’s testimony in important aspects. In addition, a footprint which matched the pattern on the soles of defendant’s shoes was found on the toilet seat in the bathroom of the massage parlor.
Defendant points to several instances in which he contends the record reflects inconsistent statements made by the prosecutrix. For example, he notes that the victim testified at trial that he was wearing boots with grease, while at the preliminary hearing she said he wore black boots. At the preliminary hearing she testified that defendant’s zipper was still unfastened when they walked toward the back room and that defendant, unaided, undressed her. At trial she testified that defendant *568zipped up his zipper while proceeding to the back room and that she almost entirely undressed herself.
Assuming that these inconsistencies are significant, conflicts and even testimony which is subject to justifiable suspicion do not justify the overturning of a judgment, because it is the exclusive province of the trier of fact to determine the credibility of a witness and the truth or falsity of the evidence upon which a determination depends. (People v. Stender (1975) 47 Cal.App.3d 413, 424 [121 Cal.Rptr. 334].)
Defendant also asserts that the victim’s testimony is implausible at certain points. For instance, he challenges her justification for suggesting to him that they would be more comfortable in the back room. The victim testified that she suggested the move to the back room in order to stall for time. Defendant contends that if she had really been afraid, she would not have offered to leave the relatively safer front room for the more dangerous back room. While an appellate court will not uphold a judgment or verdict based upon evidence inherently improbable,.. .testimony which merely discloses unusual circumstances does not come within the category. [In order to reject] the statements given by a witness who has been believed by a trial court, there must exist either a physical impossibility that they are true, or their falsity must be apparent without resorting to inference or deductions. ..(People v. Stender, supra, 47 Cal.App.3d 413, 424.) While the victim’s explanation for suggesting a move to the back room may be questioned, she did not testify to a physical impossibility and her testimony on the point was not apparently false.
The evidence was sufficient to support the verdict.
III
Defendant contends that the finding of weapon use was not supported by the evidence for three reasons: (1) Officer Loesch found the scissors in the medicine cabinet in the bathroom—where they are normally kept—and the victim offered no explanation of how they found their way back into the cabinet; (2) no fingerprints could be found on the scissors; and (3) according to the victim’s own testimony, the scissors were in defendant’s pants which were lying on the floor during the acts of sexual intercourse and oral copulation. Thus, it cannot be said that he “used” a deadly weapon.
*569These contentions cannot be sustained. There was testimony upon which a jury could have found beyond a reasonable doubt that defendant in fact used a deadly weapon. The victim testified that she awoke to find defendant standing over her and holding the 18-inch scissors and that she complied with defendant’s demands because she was afraid for her safety and continued to be afraid. Finally, an expert witness testified that there were smudges on the scissors and that it was not unusual not to find fingerprints on articles of evidence.
IV
Defendant’s final contention is that the trial judge’s determination that he is not an MDSO was neither supported by the record nor based on the merits, but was instead the result of the personal objections of the judge to current law and administrative practices governing the treatment of MDSOs. He argues that the judge ruled based on the fear that the defendant might be released on outpatient treatment after only one year of confinement and supports his contention by citing a statement made by the trial judge three days before his ruling:
“My basic consideration is to the community. This man has raped and committed serious sexual abuses on two women for which he has been convicted... .
“Now, if I was assured, somehow, and I will speak quite frankly, that this community would be secure from his future conduct for a considerable period of time, I wouldn’t care either way. I wouldn’t have any problem going either way, either place, if it would bring about his possible rehabilitation. Then give him a break and go to Atascadero.
“But if he is going to be released from Atascadero on an outpatient basis in a year, I don’t know what we are going to do. Unfortunately, the law used to be that you would be there for ninety days, they would come back with a report, we would have some indication from them.”
As stated in People v. Moore (1968) 257 Cal.App.2d 740, 750 [65 Cal.Rptr. 450], “[i]t is fundamental that the trier of fact, be it court or jury, must not consider the subject of penalty or punishment in arriving at its decision of guilt or innocence.” The issue in Moore, as in the instant case, surrounded the defendant’s mental state. The trial judge ruled that the defendant had not established that he had suffered from a diminished mental capacity during the commission of a homi*570cide. The trial judge in Moore, therefore, refused to reduce the degree of the crime from murder to manslaughter. The Court of Appeal in its decision reversing the judgment stated: “It seems inescapable. .. that at least one of the reasons the court refused to reduce the degree of crime to manslaughter was its belief that society needed protection from defendant by ‘a more permanent, more lengthy’ period of confinement.” (People v. Moore, supra, at p. 751.)
Moore is readily distinguished. There the trial judge apparently believed that the possible length of confinement was a relevant consideration in determining whether the level of culpability was to be reduced on a showing of diminished capacity. (People v. Moore, supra, 257 Cal.App.2d 740, 751.) In contrast, the trial judge’s decision in the instant case, while obviously expressing his personal disapproval of the present state of the law with regard to MDSOs, was not based on the erroneous view that the length or type of confinement is an actual element in the standard for determining whether an individual is an MDSO. While three of the five expert witnesses (a licensed clinical social worker, a clinical psychologist and a neuropsychiatrist) testified that defendant was an MDSO, two psychiatrists testified that he was not an MDSO. The trial judge stated, in ruling that the defendant did not come within section 6300 of the Welfare and Institutions Code, his reasons for so finding: “[The] Court is of the belief at this time that he does not, I don’t think the proof is there, that’s beyond a reasonable doubt. There is testimony which I will accept that he has certain personality problems, but it strikes me that those personality problems are not any more unique than many of the defendants who appear before this Court, nor are they particularly unique that appear before Court in civil matters, particularly in domestic relations matters. I think the proof is insufficient.”
These remarks do not suggest that the judge believed that the length of confinement must be a factor in a decision to determine whether a defendant is an MDSO; on the contrary, the language indicates that the judge ruled on the merits. A ruling based on substantial evidence and made on the merits may not be reversed on appeal.
The judgment is affirmed.
Caldecott, P. J., concurred.