Saying that Terrence G. Johnson deserves to go free, a group has begun a campaign for the release of the black prisoner who was convicted as a teenager in the 1978 slayings of two white police officers, a crime that inflamed racial tension in Prince George's County for months.

Johnson, now halfway through a 25-year sentence, was 15 when he grabbed a pistol from an officer's holster in the fingerprinting room of a Prince George's police station in the early hours of June 26, 1978. He shot and killed the officer, Albert M. Claggett IV. Seconds later, outside the room, he shot and killed another officer, James B. Swart.

He had been arrested for a petty crime he did not commit and said later that he had shot Claggett because the officer was beating him and he feared for his life. In the moments after shooting Claggett, Johnson said, he became temporarily insane and had no control of himself when he shot Swart.

Hundreds of people from the black community in Prince George's took to the streets in his defense, saying the Johnson case was an example of routinely brutal treatment of blacks by police. In the most racially divisive criminal case in the county's memory, a jury convicted Johnson in 1979 of manslaughter in Claggett's death, and found him not guilty by reason of temporary insanity in the slaying of Swart.

Now, in a campaign that organizers said they hope will not reopen old wounds, a committee, Justice Denied, has called on Maryland's Parole Board to grant Johnson his freedom at a Feb. 5 hearing.

Maryland prison officials "have a gem in Terrence Johnson," said Taalib-Din Ugdah, one of the group's organizers, at a news conference yesterday. Ugdah said Johnson has earned a high school equivalency diploma and a college degree in business administration in prison and has taught science, English and math to other inmates. "He's a model," Ugdah said, "someone they can parade before the public as an example of the rehabilitative process."

Ugdah said the committee, with about 30 active members, has gathered about 700 signatures on petitions calling for Johnson's release and about 150 letters of support. He accused parole officials of unfairly denying Johnson parole three times in the last four years.

In 1979, Circuit Court Judge Jacob S. Levin sentenced Johnson, who had been tried as an adult, to a maximum 15 years in prison for manslaughter and a maximum 10 years for illegal use of a handgun, to be served consecutively.

If not for the notoriety of the case, Ugdah said, Johnson would have been paroled already. "The system took aim at a 15-year-old boy," Ugdah said, "and misfired once when they tried him as an adult. They misfired again when they took away five years of his teenage life and half his adult life."

In interviews, senior police officials and rank-and-file officers said a decision to parole Johnson likely would prompt a range of reactions among members of the force, from disappointment to outrage. But none predicted a reaction as strong as the sickout that followed the verdicts in 1979, when, on April 2, only eight of 150 police officers came to work for the 8 a.m. shift.

Janet Bacon, the Parole Board's administrator, said she could not discuss Johnson's case yesterday because his file was unavailable to her.

Johnson is imprisoned in the Baltimore City Correctional Center. Ugdah said he and others in his group have advised Johnson not to grant media interviews in the weeks before his parole hearing.

At yesterday's news conference, Ugdah quoted the Rev. Martin Luther King Jr.: "Freedom is never voluntarily given . . . . It must be demanded. Justice too long delayed is justice denied."

"And so it is with Terrence Johnson," Ugdah said. "He too is waiting . . . . He has met every criteria for release, and more. To continue his incarceration is criminal."