Gideon Nieuwoudt, a former South African police colonel who confessed to taking part in the death of anti-apartheid activist Steve Biko and was convicted of killing several other opponents of white rule, died in prison Aug. 19.

Mr. Nieuwoudt, who was in his mid-fifties, had cancer of the lungs that spread to the rest of his body, his attorney, Jan Wagener, told the South African Press Association.

He was convicted of killing three black policemen and their informant in 1989, three anti-apartheid activists in 1985 and numerous other opponents of white racist rule.

He admitted involvement in Biko's death, saying he hit the "arrogant" activist with a rubber hose during interrogation. Biko died of brain injuries in September 1977 after abuse in police custody.

Mr. Nieuwoudt repeatedly was refused amnesty by South Africa's Truth and Reconciliation Commission, which pardoned about 1,000 people who confessed to their crimes as part of efforts to heal the wounds of apartheid.

At the time of his death, he was awaiting the outcome of his latest application for amnesty -- for the 1989 car bomb killing of the three police officers and the informant. He admitted placing explosives in the vehicles of the men, regarded as liabilities by their superiors.

Mr. Nieuwoudt's face became familiar to TV viewers from footage broadcast in 1989, when he, accompanied by a camera crew, went to the family of slain student leader Siphiwo Mtimkhulu to ask forgiveness for his role in the killing. Mtimkhulu's teenage son hit Mr. Nieuwoudt on the head with a vase, fracturing his skull.

A psychiatrist testified at an amnesty hearing last year that Mr. Nieuwoudt suffered from post-traumatic stress disorder brought on by a 1987 attack in which he drove through a shack, killing an armed guerrilla and his girlfriend inside.

"I think Mr. Nieuwoudt just killed too many people, and it just became too much for him," the psychiatrist, Peter Crafford, said.

Survivors include his wife, Colleen, three sons and a daughter.