LOS ANGELES, Jun. 10 – Mary Brunner, a prosecution witness in the murder trial of Robert K. Beausoleil signed an affidavit admitting perjury in testimony against him because “I couldn’t stand to be free and have the others in jail,” it was brought out in court Tuesday.

The disclosure came during an argument by Beausoleil, 22, for a new trial and reduction of the death sentence. Beausoleil, convicted of first degree murder in the torture slaying of musician Gary Hinman last July, is acting as his own attorney.

Miss Brunner’s mother, Mrs. Elsie Brunner, told Superior Court Judge William B. Keene that she discussed the affidavit with her daughter last Friday in Eau Claire, Wis.

Under questioning by Dep. Dist. Atty. Burton Katz, Mrs. Brunner said: “I asked her why she signed it and she said ‘I couldn’t stand to be free and have the others in jail.”

It is believed Miss Brunner, 26, a member of Charles Manson’s hippie clan and mother of a baby boy fathered by Manson was referring to murder indictments brought against Manson, Susan Denise Atkins and Bruce Davis in the Hinman slaying.

The indictments were returned after Miss Brunner testified before the County Grand Jury that she, Beausoleil and the three others all were present during the weekend Hinman was murdered in his Malibu home.

In her affidavit, signed May 21 in Madison, Wisc. Miss Brunner said she was “coerced” into testifying before the grand jury and at the Beausoleil trial by the district attorney’s office because she feared losing her baby.

She testified after being promised “complete immunity” if she cooperated with the district attorney’s office in all court actions arising from the Hinman murder.

Katz asked Mrs. Brunner, who now has custody of Manson’s son, Michael Manson, 2, what her daughter said after she testified at the Beausoleil trial.

Relating a conversation that took place at the family home in Eau Clair, Mrs. Brunner told the court, “I said, ‘Now Mary, did you go out to California and tell the truth?’

“She said, ‘I could have made it worse for Charles (Manson).”

Katz maintains that Miss Brunner told the truth to the grand jury and during the trial and that her affidavit is false.

By DOUG SHUIT