Former "Sons of Anarchy" actor Johnny Lewis did not have drugs -- of any kind -- in his system when he killed his landlady and then fell off a roof to his death ... this according to the autopsy report.
Lewis' autopsy results were released Thursday, and revealed he was clean of alcohol and drugs during the bizarre incident back in September.
As TMZ previously reported, Lewis had been released from jail just 6 days before the killings of 81-year-old Catherine Davis, and her cat, in L.A.'s Los Feliz neighborhood. His rap sheet included a string of drug-related crimes.
One strange note from the autopsy report -- Lewis' body had nail marks on both sides of his neck, and he appeared to have suffered partial strangulation.
Lewis was the lone suspect in Davis' death.