I have never looked into it. Is there some doubt that he actually did it or is he just a leftist liberal notable who gets forgiven for all manner of evil acts?
He confessed publicly and in his autobiography to the statutory rape. He however is claiming that he didn't drug her, just provided alcohol. Boiled down his argument was she basically didn't put up enough of a fight, that he took for 'consent'. The victim disputes that.
He took a sweetheart plea deal for reducing five felonies down to one count of unlawful sexual intercourse with a minor, with "no more than 90 days" in prison. Even that slap on the wrist was apparently too much for him, so he fled the country.
So, yes, it is beyond a doubt that he committed rape. Some of the other details are disputed, but not the core. And yes, the argument is somehow his politics and artistic ability outweigh his crime and refusal to take even the lightest sentence for it.