LOS ANGELES - Model-turned-bounty hunter Domino Harvey - whose tumultuous life inspired an upcoming film starring Keira Knightley - has been found dead in her bathtub, authorities said yesterday.

An autopsy failed to reveal what killed the 35-year-old troubled beauty, they said.

The daughter of the late British actor Laurence Harvey ("The Manchurian Candidate," "Butterfield 8"), she was on probation for a 2003 methamphetamine conviction and was facing new federal drug charges when she died. But cops said there were no signs of drugs, paraphernalia or criminal activity in her West Hollywood home.

"There was nothing to indicate foul play of any kind. We don't really know anything," L.A. County Sheriff's Lt. Donnie Mauldin said.

Toxicology tests are under way to determine if any drug or substance played a role in her death, said Lt. Cheryl MacWillie, a spokeswoman for the L.A. county coroner. "There were no injuries to the body. She did not drown. She was never under water," she said.

The ex-fashion model, who traded runway glam for a dangerous job hunting bail jumpers, died Monday night.

After an early career as a Ford model, Harvey, whose mother was Vogue model Pauline Stone, decided to strike out on her own, working as a nightclub manager, a ranch hand and for the San Diego Fire Department before joining a bail bonds agency in 1994.

Named after a James Bond movie heroine, Harvey often hunted fugitive drug dealers and would reap 10% of the bail amount on those she captured.

Her unusual life story caught Hollywood's eye and became the inspiration for the movie "Domino," starring Knightley ("Pirates of the Caribbean," "Bend It Like Beckham") which is set to open Aug. 19.

Her sudden death saddened the filmmakers. "Domino never failed to surprise or inspire me over the last 12 years. She was a free spirit like no other I have ever known," said director Tony Scott.

The film sparked controversy earlier this year when British tabloids and some Web sites reported Harvey was gay and upset that the film portrayed her as heterosexual. But those reports were disputed by Harvey and her mother, according to New Line Cinema spokesman John Smith.

"As far as I know, she was straight," Smith said.

There are no plans to change the film as a result of Harvey's death. "It's inspired by her, but it's not based on her life story," Smith said.

Harvey's work chasing drug dealers may have rubbed off on her life. In addition to her past drug conviction, she was busted by the FBI in May in connection with alleged meth dealing. "We heard she was having some problems," Smith said.