SACRAMENTO, Calif. (AP) â€” The self-described right-hand man of cult leader Charles Manson, who was convicted of orchestrating the Tate-LaBianca slayings 42 years ago, has his latest parole hearing scheduled Wednesday in a California prison. Charles "Tex" Watson, 65, has been denied parole 13 times but will try again during a hearing at Mule Creek State Prison in Ione, in the Sierra foothills 50 miles southeast of Sacramento. 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 on Aug. 9, 1969. The next night, he helped kill grocery owners Leno and Rosemary LaBianca. "There's no question these were some of the most horrific crimes in California history in terms of the brutality, the multiple stab wounds, the gunshots, the large number of victims over a two-day period," said Los Angeles County Deputy District Attorney Patrick Sequeira. "For a group of people to just slaughter strangers in hopes of igniting a race war is extremely horrifying." Watson's attorney, Cheryl Montgomery, did not return repeated telephone messages. Watson married and divorced in prison and has four children from conjugal visits, but his family did not respond to a request for comment that was left through the website that promotes Watson's prison ministry, http://www.aboundinglove.org. The website says he was raised in Copeville, Texas, north of Dallas, and headed to California in 1967 after dropping out of college. A brief biographical sketch on the site said Watson believed Manson "offered utopia, but in reality, he had a destructive world view, which Charles ended up believing in and acting upon. His participation in the 1969 Manson murders is a part of history that he deeply regrets." A book he wrote while in prison is titled, "Manson's Right-Hand Man Speaks Out!" In the past, Watson has argued that he is a changed man who has been a model prisoner and no longer is a danger to the public. He did not attend his last parole hearing in 2006 but was portrayed in a psychiatric evaluation at the time as "a very devout fundamentalist Christian ... a young, naive and gullible man (who) got into drugs and bizarre company without appreciating the deviance of the company he was keeping." Anthony DiMaria, a nephew of victim Jay Sebring, planned to contest that view of Watson and other Manson disciples. "They've often been portrayed as these victims of Manson, and they are killers. They're mass murderers," DiMaria said in a telephone interview before the hearing. He planned to attend the hearing with his mother and sister. Debra Tate also was expected to speak to the two-member panel of the California Board of Parole Hearings on behalf of her late sister, Sharon, who at the time was married to film director Roman Polanski. Watson was convicted in a separate trial after Manson and three female followers were found guilty of the seven murders. Their death sentences were commuted to life when the U.S. Supreme Court briefly outlawed the death penalty in 1972. DiMaria said his mother has considered it her mission to speak out on behalf of her brother. "I know that our family, myself included, feel no hatred, anger or vengeance toward them. We actually go out of love for the victims, and we also go out of justice. This is calculated, cold-blooded mass murder in which bodies were desecrated," DiMaria said. "We want to bring the memories of the victims into the room as the commissioners deliberate on whether to parole the inmate."