Gibson in domestic violence probe
Mel Gibson is being investigated over a domestic violence incident involving his ex-girlfriend, Russian singer Oksana Grigorieva, earlier this year.
The disclosure came after Los Angeles detectives interviewed Grigorieva about the alleged attack at an undisclosed location in Malibu.
Sheriff's spokesman Steve Whitmore said Grigorieva was the only person interviewed so far in the case.
The 54-year-old Braveheart and Lethal Weapon star and Grigorieva have been involved in a bitter custody dispute over their baby daughter - the subject of a confidential court case.
Mr Whitmore refused to disclose further details of the domestic violence investigation or any potential evidence.
"We're in the process of verifying, verifying, verifying," he said. "All the allegations that have been put forth will be thoroughly investigated."
The actor has not publicly discussed the break-up with Grigorieva, 40. The former couple first revealed their relationship shortly after Gibson's wife Robyn filed for divorce last April.
Court proceedings in the case involving the eight-month-old daughter of Gibson and Grigorieva have been conducted in closed session.
Gibson's lawyer Stephen Kolodny said previously the actor had paid Grigorieva "tens of thousands of dollars" and provided her with a home, vehicle and nanny since their break-up.
He also accused the singer of breaking the terms of a confidential custody agreement reached in May. Grigorieva has said she cannot discuss the case.