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.
