The self-styled "right-hand man" of cult leader Charles Manson is seeking parole from a California prison.

Charles "Tex" Watson, who is 65, has been denied parole 13 times for orchestrating the Tate-LaBianca slayings in Los Angeles 42 years ago. He will try again during a hearing Wednesday at Mule Creek State Prison.

Four relatives of Watson's victims plan to ask that his parole be denied for killing actress Sharon Tate, who was eight months pregnant, and four others at her Beverly Hills home in 1969. The next night, he helped kill Leno and Rosemary LaBianca.

Los Angeles County Deputy District Attorney Patrick Sequeira calls them "some of the most horrific crimes in California history." Watson's attorney, Cheryl Montgomery, and his family did not respond to requests for comment.