Discrepancies in court testimony indicate that a conspiracy by law enforcement officials could have sparked the 1971 prison killings blamed on former fugitive lawyer Stephen M. Bingham, his attorney argued today.

Bingham, 44, a Yale graduate from a distinguished Connecticut family, is accused of smuggling an Astra 9 mm semi-automatic pistol, ammunition and an Afro wig to Black Panther leader George Jackson in San Quentin prison so that the celebrated prisoner-author could escape.

After 13 years underground, Bingham has been on trial on murder and conspiracy charges for 2 1/2 months. In closing arguments, defense attorney M. Gerald Schwartzbach said the unexplained failure by prison officials to prepare for Jackson's threatened breakout should lead jurors to wonder whether Bingham was the dupe of supervisors who wanted Jackson dead.

Minutes after seeing Bingham in a prison visiting room, Jackson allegedly pulled the pistol and ammunition out of the wig he had been wearing and began a rampage in which three guards and two white prisoners were killed. Prosecutors say a prison guard shot Jackson to death as he ran toward the compound's north wall. Bingham has been charged in two guard's slayings.

Sixty spectators -- some of them standing -- packed themselves into a courtroom designed for half that many as Schwartzbach recounted then-warden Louis Nelson's failure to tighten security after authorities intercepted a letter from Jackson referring to escape plans.

"Somebody wanted George Jackson to think he could escape. They wanted him to try," Schwartzbach told the jurors. "Do you reject it out of hand? If you reject it out of hand, you are closing your mind to it."

The Marin County Superior Court jury of 10 women and two men listened attentively as Schwartzbach lectured on their need to presume Bingham innocent and consider alternative explanations for the Aug. 21, 1971, prison killings.

Schwartzbach took the jurors through several inconsistent accounts of Jackson's death and suggested that he was killed by a handgun fired by an unknown assailant rather than by a rifle-bearing prison guard. Alluding to Bingham's disappearance afterwards, he said, "You have to appreciate what things were like in 1971."

Bingham has said he fled to Europe because he feared that he would be framed by officials who had conspired to assassinate Jackson. Schwartzbach told the jurors to consider an era in which "students were being murdered at Kent State and Jackson State. We're talking about a time when J. Edgar Hoover was running the FBI."

Assistant District Attorney Terry Boren spent much of his closing argument Monday taking jurors through a list of the 10 men -- Bingham and nine prison guards -- who saw Jackson during the minutes when he could have acquired the pistol, ammunition and wig. Only Bingham, Boren said, saw Jackson in the relative seclusion of the visiting room, and only Bingham fled without testifying.

Today, Boren noted that, in a 1974 newspaper interview that did not reveal where he was living, Bingham refused to comment on his guilt or innocence. He surrendered in 1984.

But Schwartzbach pointed out several times today that Bingham went to the prison only to take some manuscript pages to Jackson for Vanita Anderson, a Black Panther legal assistant barred from seeing Jackson because she had exhausted her monthly quota of visits.

Schwartzbach said Bingham took the pages into the visiting room and did not intend to take the tape recorder and briefcase in which the weapon and wig allegedly were hidden. Bingham has said he took the briefcase containing the tape recorder, both of which belonged to Anderson, only after a guard suggested that he might need a tape recorder. Anderson, he said, offered to lend him hers.

Monday, Boren asked why Bingham, if he knew he was innocent, would not have tried to call Anderson or other Jackson associates to find out what the briefcase had contained before he fled.

Today, Schwartzbach asked why investigators seemed to give up looking for Anderson.

At a 1972 hearing, Anderson declined to answer questions on the grounds she might incriminate herself.

Bingham's case could go to the jury by the end of the week.