SAN RAFAEL, Calif. (AP) _ Former fugitive lawyer Stephen Bingham pleaded innocent today to murder and conspiracy charges stemming from a 13-year-old San Quentin prison escape attempt in which inmate George Jackson and five others died.

While his parents watched, Bingham, 42, entered the pleas before Marin Superior Court Judge Beverly Savitt, set a September trial date. The prosecution predicted the trial would take three to six months.

Bingham, who is free on $300,000 bail, was ordered Feb. 20 to stand trial after a three-month preliminary hearing in Municipal Court that included 56 witnesses and 242 exhibits.

He was accused in an October 1971 indictment of smuggling a 9mm automatic pistol into San Quentin to George Jackson, a black revolutionary. Jackson, two other inmates and three guards died on Aug. 21, 1971, in a melee at San Quentin's adjustment center, where the state housed inmates considered the most dangerous.

Bingham, who was working on a class action lawsuit against conditions at the adjustment center, disappeared after the aborted escape attempt. He surrendered to Marin County authorities last July 9.

Bingham's attorneys have argued that Jackson, then one of the nation's best-known prison radicals, was the victim of a plot by state prison officials and others to lure him to his death through a no-win escape attempt.

After today's court appearance, defense attorney Leonard Weinglass told reporters the defense planned to attack on the state's theory that Bingham was the only person who could have slipped Jackson the gun.