A terminally ill prisoner whose 1963 murder of a policeman was chronicled in the book and film The Onion Field was denied compassionate release on Tuesday after he said he didn't want to be freed, officials said.

The California Board of Parole Hearings said inmate Gregory Powell, 78 and suffering from cancer, is not willing to be released and the board considered that in its ruling to keep him in custody.

The 12-member panel, after a hearing in Sacramento, California, said in a statement that Powell's release would pose a threat to public safety due in part to his lack of cooperation with prison rules.

Powell is serving a sentence of life with the possibility of parole for his conviction in the 1963 murder of Los Angeles Police officer Ian Campbell, said Terry Thornton, a spokeswoman for the California Department of Corrections and Rehabilitation.

He is being held at the California Medical Facility prison in Vacaville, California, and he was considered for compassionate release because he was ill with six months or less to live, Thornton said.

Powell and his accomplice, the late Jimmy Lee Smith, kidnapped Campbell and his partner Karl Hettinger, both plainclothes officers.

Powell and Smith disarmed and kidnapped the officers at gunpoint in the Hollywood section of Los Angeles.

Powell and Smith then took the two officers about 90 miles north to an onion field in rural Bakersfield, and once there Powell shot to death the 31-year-old Campbell. Hettinger managed to escape.

Thornton declined to discuss what type of illness Powell suffers from, but a Los Angeles Police Protective League official said it was cancer.

The kidnapping of the two police officers and the killing of Campbell were detailed in the book The Onion Field and a 1979 film of the same name. James Woods portrayed Powell in the movie, which starred Ted Danson as Campbell.

To have released the man who kidnapped and callously executed Officer Ian Campbell would have been a travesty of justice, Los Angeles District Attorney Steve Cooley said in a statement, after the decision was made to not release Powell.