Does third party evidence raise a reasonable doubt as to the guilt of a defendant in a sexual assault case?

Third party culpability evidence clearly raises a reasonable doubt as to the defendant's guilt where the evidence otherwise establishes that the crime was committed by one person; in that circumstance, if the third party committed the offense, the defendant, perforce, is not guilty. The situation is more difficult, however, where the evidence is sufficient to show that multiple perpetrators committed the crime or in other circumstances where a third party's culpability does not suffice to absolve the defendant's guilt. (See People v. Hall, supra, 41Cal.3d at p. 835 [noting that evidence of a third party's participation would not tend to exculpate the defendant where there was "no testimony or circumstantial evidence limit[ing] the number of perpetrators"].)