Los Angeles police are investigating movie mogul Harvey Weinstein over a suspected sexual assault in 2013.
They said a potential victim had been interviewed, without giving further details.
He already faces allegations of sexual misconduct and assault from dozens of women. He has "unequivocally" denied having "non-consensual sex".
Separately, film director Quentin Tarantino said he long knew about Mr Weinstein's alleged misconduct.
"I knew enough to do more than I did," Tarantino said in an interview with the New York Times.
"There was more to it than just the normal rumours, the normal gossip. It wasn't second-hand. I knew he did a couple of these things.
"I wish I had taken responsibility for what I heard. If I had done the work I should have done then, I would have had to not work with him," Tarantino added.
The Hollywood director has worked closely with Mr Weinstein on many of his films, including Django Unchained and Inglorious Basterds.
The LA police inquiry is the first criminal investigation involving Mr Weinstein in California.
"The Los Angeles Police Department's Robbery Homicide Division has interviewed a potential sexual assault victim involving Harvey Weinstein which allegedly occurred in 2013," LAPD spokesman Sal Ramirez told the BBC.
"The case is under investigation. There is no more information at this time."
It falls within California's 10-year statute of limitations for the crime of rape, and could lead to a trial if prosecutors decide they have enough evidence to support a case against the filmmaker.
The alleged victim is a 38-year-old Italian model and actress, according to US media outlets.
She is reported to have met with detectives this week.
Separate investigations into Harvey Weinstein are already under way in New York and London.
Earlier on Thursday, film star Tom Hanks said he believed there was now no way back for Mr Weinstein.
"We're at a watershed moment, this is a sea change," Hanks told the BBC.
"His last name will become a noun and a verb. It will become an identifying moniker for a state of being for which there was a before and an after."
Hanks, who is on the board of the organisation behind the Oscars, the Academy of Motion Picture Arts and Sciences, said he could not comment on the recent decision to expel Mr Weinstein as a member.
Mr Weinstein also left the board of The Weinstein Company earlier this month.
He has admitted his behaviour has "caused a lot of pain" - but has described many of the allegations against him as "patently false".
His spokesperson has said that "any allegations of non-consensual sex are unequivocally denied" and that there were "never any acts of retaliation" against women who turned him down.