Johnny Lewis, who played Kip "Half-Sack" Epps in the FX show, is the only suspect in the death of 81-year-old Catherine Davis, according to Los Angeles police.
Authorities found them dead Wednesday morning after neighbors reported a woman screaming inside the home, Cmdr. Andrew Smith said.
Lewis' death ended in a turbulent nearly 10-month span during which he was repeatedly arrested and officials expressed concerns about his mental health and the danger he posed to others.
The home where Davis was found had been ransacked, glass was shattered and a dead cat was found.
Neighbors said a man had jumped a fence and assaulted a painter and homeowner next door.
The body of Lewis, 28, was found in the driveway. He could have jumped or fallen from the roof, garage or balcony, or tumbled down stairs from a patio area, Smith said.
It appears Davis had been beaten, Smith added.
Because of the circumstances, investigators were checking whether Lewis was on drugs or had mental health issues, Smith said.
The deaths came about four months after a probation official expressed grave concern about Lewis' mental health. The report was prepared in a case in which Lewis was accused of attempting to break into the home of a woman in Santa Monica, Calif., and it described him as a transient. That case came about six weeks after Lewis hit two men over the head with a bottle during a fight.
The probation official wrote of being "very concerned for the well-being of not only the community but that of the defendant."
The May 17 report goes on to state that "the defendant suffers from some form of chemical dependency, mental health issue and a lack of permanent housing. Given this, (Lewis) will continue to be a threat to any community he may reside."
Within days, Lewis was released to a treatment facility and he pleaded no contest to attempting to break into the home in mid-August.
He was placed on three years of supervised probation, sentenced to time-served in jail and no follow-up hearing was scheduled, court records show.
Lewis' attorney Jonathan Mandel said the actor had serious mental issues that seemed to surface fairly recently. He said Lewis' parents and others had tried desperately to help him.
"Johnny Lewis had a lot of problems, a lot of mental problems," Mandel said by phone Thursday. "I recommended treatment for him but he declined it."
He continued, saying: "I give a lot of credit to his parents. They were really strong in trying to help him out. They really went to bat for him, but I guess they just couldn't do enough."
Lewis was released from Los Angeles County Jail a week ago, according to court records.
He had pleaded no contest to assault with a deadly weapon and attempted burglary in separate cases, according to the records.
"Obviously defendant's behavior is out of control and needs counseling afforded by a professional," another probation officer wrote in a report filed in Lewis' assault case.
Both probation reports state Lewis said he was earning about $20,000 a year as an actor in recent years, and he had been living with his parents when he was first arrested in January. In both cases, he was ordered to stay away from drugs.
Lewis' career spanned more than a decade, mainly in small roles. He played Ricky in the 2007 movie "AVPR: Aliens vs Predator - Requiem" and was Dennis "Chili" Childress for two seasons on TV's "The O.C." He also appeared in episodes of such popular television shows as "Boston Public," ''Judging Amy," ''Malcolm in the Middle" and "Drake & Josh."
He was on "Sons of Anarchy" in 2008 and 2009 before his character was killed off.
Kurt Sutter, the show's creator and executive producer, tweeted news of Lewis' death Thursday:
"It was a tragic end for an extremely talented guy, who unfortunately had lost his way," Sutter wrote. "I wish I could say that I was shocked by the events last night, but I was not. I am deeply sorry that an innocent life had to be thrown into his destructive path."
AP writer John Rogers in Los Angeles contributed to this report.