[4] Assisted by accomplice Jimmy Lee Smith, Powell took the officers to an onion field near Bakersfield, California, where Campbell was fatally shot.

[1][2] His father was often absent due to his career as a musician and his mother had health problems, leaving Powell to take care of his three younger siblings.

[1][2] At age 15, Powell ran away from his home and hitchhiked to Florida, where he met a Catholic priest and they had a brief sexual relationship.

[11][12] At one point in his life, after he and his family moved to California, Powell underwent a craniectomy or craniotomy at Vacaville Medical Facility to remove a brain tumor.

[14][15] At about 10:00 p.m.[14] on March 9, 1963, Los Angeles Police Department (LAPD) officers Ian Campbell and Karl Hettinger pulled over a 1946 Ford coupe at the corner of Carlos Avenue and Gower Street for an illegal U-turn.

[19] With Smith's help, Powell abducted both of the officers and forced Campbell to drive them to an onion field in Bakersfield, California.

[14][17][20] When they arrived at the onion field, Campbell and Hettinger were forced out of the car and ordered to stand with their hands above their heads.

When I looked back, they fired at me...."[23] Hettinger successfully managed to escape from Powell and Smith, running four miles (6.4 km) to a farmhouse.

[15][26] Powell was arrested a few hours later by a California Highway Patrol officer after attempting to escape via a stolen car.

However, John Mancino, founder of Citizens for Truth, was able to submit a legal brief to the First District Court of Appeals in San Francisco ordering Powell to remain in prison.

[34] His lawyer, Dennis Riordan, blamed their court loss on a February 1982 television airing of The Onion Field, the film adaptation of Joseph Wambaugh's book on the case of the same name.

[50] Tyler Izen, president of the Los Angeles Police Protective League, issued a statement: "Gregory Powell was a cold-blooded murderer who avoided the death penalty, but he won't escape God's judgment.