Gibson's former girlfriend and the mother of his 8-month-old daughter, Oksana Grigorieva, accuses the actor of domestic violence. The alleged incident occurred Jan. 6 at an undisclosed location in Malibu.
Grigorieva recently released cell phone conversations with a man purported to be Gibson. The man on the tape hurls insults and threats against Grigorieva.
On one recording, a voice sounding distinctively like the 54-year-old actor is heard telling Grigorieva that she "deserved" to be hit after she chastised him for allegedly punching her in the face and breaking two of her teeth.
Authorities are also investigating claims the 40-year-old Russian singer or someone close to her was trying to extort money from the actor.