VACAVILLE, Oct. 18 — The California parole board has advanced the parole date of Steve “Clem” Grogan, a convicted murderer and follower of Charles Manson.

A panel of the state Board of Prison Terms decided Tuesday that Grogan, 33, may be released in April of 1986 instead of the original parole of date of 1988. The board cited good behavior.

Grogan was convicted in 1971 of the death of Shorty Shea, a worker at the Spahn Movie Ranch in the San Fernando Valley where Manson and his followers lived. Shea was stabbed and beheaded. His remains were found in 1977, when Grogan told authorities where he had buried the body.

Manson and other members of his clan were convicted for the 1969 slayings of actress Sharon Tate and six others.

While Incarcerated, Grogan has been active in the Irene Larson Center for the Handicapped, has participated in the Vacaville March of Dimes and Multiple Sclerosis “Love Run,” and in child care at the prison.

The board said Grogan has also been involved in the visual and performing arts at the prison.