LOS ANGELES, Jan. 30 — Susan Murphy, a Charles Manson cultist, and her escape companion, Diane Ellis, have been sentenced to 10 extra years in prison for beating a guard unconscious while escaping in August from Terminal Island Federal Prison.

U.S. District Court Judge Malcolm Lucas called the attack on Melinda Eisenhart, 25, “severe and brutal” and ordered the women to serve the additional years after they complete current terms for other crimes.

Miss Murphy, 34, and Miss Ellis, 33, pleaded guilty in November to charges of assault on a federal officer. The officer recovered.

Miss Murphy, described as a fringe member of the Manson cult, was sentenced early in 1976 to a five-year term for conspiring with fellow cultist Sandra Good to write threatening letters to business leaders they accused of creating pollution.

Miss Ellis, described as the “mastermind” of the escape, had been convicted of a 1968 bank robbery.

During the escape, prosecutors say, Miss Eisenhart was struck 30 to 50 times with two pipes taped together. The two women then fled in the guard’s car, authorities said.