The 28-year-old actor, best known for his roles in Sons of Anarchy and The OC, was found by the Los Angeles Police Department in a driveway in the Los Feliz area, ABC reports.
Officers had been called to the home after responding to reports of a woman screaming, and the body of a woman in her 70s was found in the home.
LAPD Commander Andrew Smith told ABC News affiliate KABC: "He appeared to have died from some type of fall, either from the stairway, or from the balcony, or from one of the roofs.
"The best we're piecing together now is that it appears that some type of altercation occurred inside of the house resulting in the death of the woman.
"Then this individual ran outside, had an altercation with a couple of neighbours, ran back into the house and, by the time we got here, he had fallen or had somehow died on the driveway."
A handyman and neighbor were reportedly badly beaten after a confrontation with Lewis.
Lewis played Dennis Childress on The OC and Kip 'Half-Sack' Epps on Sons of Anarchy for two seasons.