SACRAMENTO, Apr. 13 — Sandra Good, a follower of convicted mass murderer Charles Manson and former roommate of Lynette (Squeaky) Fromme, was sentenced today to 15 years in prison for conspiring to threaten the lives of business and government leaders.

Miss Good’s codefendant, Susan Murphy, was sentenced to five years in prison.

The judge in the case was the same one who sentenced Miss Fromme to life in prison last December for trying to kill President Ford.

U.S. Dist. Judge Thomas J. MacBride said the two had committed “acts of terrorism” comparable to hi-jackings.

They were convicted March 12 by a jury on charges of conspiring to mail threatening letters to those they accused of polluting the earth.

Miss Good also was convicted of making threats in telephone interviews with radio stations and a newspaper.

“I’m satisfied that if either or both of you were put back on the streets today, that you would immediately assume your evil conduct,” MacBride said.

Miss Good, 32, was given five years for each of three counts, the sentences to run consecutively.

Miss Murphy, 33, was given the maximum five-year sentence for the one count of conspiracy against her.

Miss Good will be eligible for parole in five years, Miss Murphy in 20 months.

The judge said he could not take into consideration copies of death threat letters Miss Murphy allegedly mailed while the trial was under way.

Asst. U.S. Atty. Bruce Babcock said of Manson’s so-called family: “They’re all in jail. I don’t know what they can do now.”

At the sentence hearing, both women asked to be sent to prison and engaged in a long debate with MacBride.

“You’re killing or allowing to be killed the air, the water, the land, the trees, the wildlife,” Miss Good lectured the judge before he pronounced sentence.

Miss Fromme, an early member of Manson’s so-called family, and Miss Good were sharing a Sacramento apartment when Miss Fromme was arrested Sept. 5 near the Capitol on a charge of trying to kill President Ford.

Miss Fromme was also named as an unindicted coconspirator in the letter-mailing plot, which prosecutors said involved a conspiracy to mail threatening letters to a long list of businessmen, government leaders, companies and organizations.

The letters and Miss Good’s interview statements accused certain persons of polluting the environment and warned that they would be killed by an “International People’s Court of Retribution” unless the polluting stopped.

Miss Good said the letters and statements were helpful warnings and denied that she was personally making the threats. But prosecutors contended there was no such thing as a court of retribution.

The women’s trial ended abruptly with the defendants protesting their innocence, putting on no defense and saying they wanted to go to prison.

Miss Fromme was the only defense witness called, and she was carried from the courtroom by U.S. marshals. She said she would not testify unless Manson and his followers now in prison for the 1969 murder of Sharon Tate and others were given a new trial.