Received three life sentences for murdering three people between 1998 and 2005.
He once worked at Home Depot but was fired for punching a customer in the face.
He shot people he inexplicably deemed threats, and he did so without emotion; he was not motivated by lust or pleasure.
He did not marry but fathered one son with a girlfriend.
He was once featured on ABC's "20/20," hosted by Elizabeth Vargas.