FRONTERA, Dec. 18 — Former Charles Manson follower Susan Atkins was called a risk to society, accused of showing poor judgment in marriage and denied parole a fifth time for the 1969 cult murders of actress Sharon Tate and seven others.

California Board of Prison Terms Chairman Robert Carter said Miss Atkins was denied freedom Thursday because she still poses “an unreasonable risk to the safety of the public” and because her ill-fated marriage to Donald Lee Laisure, a self-proclaimed Texas millionaire, showed “poor judgment.”

Carter said Miss Atkins, 34, would not be considered for parole again until 1985 because a new state law allows such hearings only once every three years for convicted mass murderers.

Miss Atkins missed the parole board’s ruling because she was watching a prison screening of the movie “E.T., the Extraterrestrial” after sitting through two hours of testimony earlier in the day at the California Institution for Women 40 miles east of Los Angeles.

Miss Atkins was convicted along with Manson, Patricia Krenwinkle and Leslie Van Houten, all of whom are serving life sentences for the murders of Miss Tate and four others at director Roman Polanski’s Laurel Canyon home — and the killings next day of grocery store owners Leno and Rosemary LaBianca.

In addition, Miss Atkins and Manson were convicted in the torture-murder of musician Gary Hinman.

At the outset of Thursday’s hearing, the board declined to receive a letter purportedly written by the 53-year-old Laisure, Miss Atkins’ estranged husband whom she married in a prison ceremony last year. He has since filed for divorce.

Deputy District Attorney Stephen Kay said the letter was addressed to an NBC reporter and claimed that Miss Atkins had stabbed Laisure twice while he was visiting her but that the incident had not been reported to prison authorities.

A copy of the letter, made available to The Associated Press, also stated that Miss Atkins had made death threats against her husband and Charles Manson. The letter was not signed, but had Laisure’s name in the letterhead and his name was typed at the bottom.

Kay said he received the letter only Tuesday, and board members agreed to an objection by Miss Atkins’ attorney, Robert Moss, that it had not been submitted to them in a timely manner. Moss also complained that the board “did not really meet the challenge of determining her role and participation in the (Tate-LaBianca-Hinman) slayings.”

However, he said he didn’t plan to appeal the decision, which does not take effect for 60 days, because it would be futile.

Although Moss told the board Miss Atkins has completely reformed since she committed the crimes, Kay described her as “one of the most cold-blooded murderers in American history” and said she should never be paroled.

Wearing a maroon dress with her long fingernails painted to match, Miss Atkins sat quietly during the hearing.

“She’s mentally, behaviorally and emotionally reformed,” Moss said.

“She’s a completely different person than she was.”

However, Kay asserted that “it would make a mockery of justice at any time of her life to parole her from this institution…. Her confession to the murder of Sharon Tate is one of the most chilling, hardened confessions that I have ever heard from a female.

“If any of these people (the Manson family) are paroled, it would be a mes-sage to our society that sooner or later, everybody’s going to get paroled, because these people participated in unimaginable horror.”

Board member Loretta Collier said during the hearing that a recent psychological evaluation found that Miss Atkins had become depressed and possibly suicidal following her father’s death the past year, but had improved somewhat since then.

Miss Atkins was originally sentenced to death for her role in the Manson slayings, but the sentence was commuted to a life prison term after the California Supreme Court ruled the state’s death penalty unconstitutional in 1972.