Los Angeles (CNN) -- Investigators believe "Sons of Anarchy" actor Johnny Lewis brutally killed his elderly landlord Wednesday before falling to his death as he tried to escape police whose sirens he heard approaching. It could be weeks before police understand the cause of what they say was a violent rampage by Lewis, 28, that led to the death of Katherine Davis, 81. Davis died from "blunt head trauma and strangulation," according to preliminary findings from the autopsy conducted Thursday, the Los Angeles County Coroner's office said. Police suspect drugs were involved, but "we don't have any hard evidence that says he was on anything right now," LAPD Commander Andrew Smith said.
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NEW: Katherine Davis, 81, died from "blunt head trauma and strangulation," coroner says
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Police suspect drugs may have been involved, but no proof yet
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Johnny Lewis, 28, apparently fell to his death, police say
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Lewis' acting resume also included "The O.C." and "Criminal Minds"
@placeholder, whose full name is Jonathan Kendrick Lewis, was born and raised in Los Angeles.