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Sons of Anarchy star Johnny Lewis did not have drugs in his system when he fell to his death after apparently killing his 81-year-old landlady in her Los Angeles home in September, according to results of the autopsy report.

Toxicology results released by the Los Angeles County coroner's office found no traces of cocaine, alcohol, marijuana or any other types of drugs -- both anti-psychotic and psychedelic -- in the 28-year-old actor's system.

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A police investigation concluded that Lewis fell to his death while trying to flee the home of Catherine Davis, who was found strangled to death on September 26.

The autopsy report also noted that Lewis had nail marks on both sides of his neck when he died and had suffered partial strangulation, indicating a possible struggle. The actor's death was ruled accidental because there was no evidence that he attempted to kill himself or was pushed.

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Lewis had three previous arrests in 2012 and probation officers had expressed concern about his mental health. His lawyer said after his client's death that drugs may have been a factor in the tragedy.