Marlon Brando's eldest son, Christian, may have killed his half-sister's boyfriend in self-defense, says lawyer William Kunstler, who will defend the younger Brando. ``I understand there may have been a struggle over the gun, and some beating going on of Marlon's daughter,'' the radical attorney said Thursday. Kunstler, a friend of Brando's from civil rights struggles, said he received a call from him at 2 a.m. Thursday just after the shooting. Christian Brando, 32, was scheduled to be arraigned today in the slaying of Dag Drollet, 26, of Tahiti, who had been staying at the Brando estate. Kunstler was reportedly flying to Los Angeles from New York for the arraignment. Police said the shooting was sparked by an argument over Drollet's treatment of 20-year-old Tarita Cheyenne Brando, Christian's pregnant half-sister. ``There were allegations that there was physical abuse, a beating,'' Lt. Ron Hall said. ``There was no indication there had been a physical altercation prior to the shooting,'' said police Detective Steve Osti. The actor's son was arrested Wednesday night and booked for investigation of murder, said Hall. He was held without bail pending arraignment. ``He admitted to the shooting,'' the lieutenant said. Drollet was a family friend who had been a guest in the home for 10 days, police said. He died instantly from a .45-caliber bullet to the head, police said. Coroner's office spokesman Bob Dambacher said an autopsy was planned today. Marlon Brando, 66, placed the 911 emergency call to report a shooting inside his Mulholland Drive estate Wednesday night, police said. Christian Brando was alone with Drollet when the shooting occurred and the Oscar-winning actor, his wife and daughter were in another wing of the sprawling mansion and didn't witness the shooting, Hall said. Tarita Cheyenne is the daughter of Brando and his current wife, Tarita Teriipia, a Tahitian actress who played his love in the 1962 remake of ``Mutiny on the Bounty.'' Brando's two other sons, Miko and Simon, were not at the estate at the time. Officers recovered the pistol used in the killing and confiscated other weapons, including an M14 carbine, a shotgun and an Uzi assault rifle. ``I don't want these guns here. Take these guns out of here,'' Marlon Brando was quoted as telling police. Christian is the son of the actor and his first wife, Anna Kashfi. The couple was divorced in 1960, and their troubled son was the subject of a bitter custody battle. The 32-year-old high school dropout struggled to find a role of his own in life. He learned artistic welding, attempted to start a tree trimming service and tried acting. In October 1987, the younger Brando worked on his first _ and apparently only _ movie. He played a hit man in an Italian film produced under the Italian title ``La Posta in Gioco'' that was called both ``Up for Grabs'' and ``The Stakes'' in English. Except for traffic tickets, Christian Brando has no police record. Marlon Brando won best actor Oscars in 1954 for ``On the Waterfront'' and in 1972 for ``The Godfather.'' He was nominated for Best Support Actor for his 1989 role in ``A Dry White Season.''