mystery out of hollywood, that ended up with an up-and-coming tv actor dead. Johnny lewis and officials say he went on a violent rampage, allegedly killing his landlady and then himself. Was a... See More
mystery out of hollywood, that ended up with an up-and-coming tv actor dead. Johnny lewis and officials say he went on a violent rampage, allegedly killing his landlady and then himself. Was a designer drug behind all of it? Abc's david wright has the latest from los angeles. David? Reporter: That's the working theory of police officers investigating this grisly murder. They found no drugs so far. But lewis' wild behavior is episoded by some on these designer drugs. Up until now, johnny lewis had been best-known for his role on "sons of anarchy." Now, he'll always be known for this. Police are saying he's also the suspect in the grisly murder of his 81-year-old landlady. Reporter: It happened on wednesday morning, at the writer's villa, a bed and breakfast for young people working in hollywood. We got two 911 calls. The neighbors called. Our officers rushed up there. By the time we got there, mr. Lewis was already dead. Reporter: Police found lewis' landlady, 81-year-old katherine davis, beaten in a dead room. Her cat dismembered in a bathroom. Eyewitnesses told police, lewis appeared to show superhuman strength. Mr. Lewis jumped over a fence into a neighbor's yard and for some reason attacked the painter. The painter and the homeowner were able to get him away. He jumped back into his yard, where he was staying. And at some point shortly thereafter, his death. Reporter: There were reports that drugs are involved. That's a possibility. Reporter: Police say they have not located any drugs. And won't know for sure until the toxicology report comes back from the autopsy. But they suspect. The thing we're seeing lately in los angeles and across country, are synthetic-like drugs. Bath salt or the one around here called smiles. Reporter: Lewis' character on "sons of anarchy" also died a violent death. Colleagues say he was troubled. The creator of his show even tweeting, I wish I could say i was shocked. But I was not. We believe that mr. Lewis was responsible for this. Reporter: Lewis had struggled with chemical dependence and issues. We was repeatedly in trouble with the law for bad behavior. In fact, he was released from jail five days before his death.
This transcript has been automatically generated and may not be 100% accurate.