A fourth co-defendant pleaded guilty Monday in the O.J. Simpson armed robbery and kidnapping case, agreeing to testify against the Hall of Fame football player and one remaining co-defendant.

Charles Ehrlich entered his plea to reduced charges of attempted accessory to robbery and attempted burglary.

Ehrlich is one of five men who accompanied Simpson during a confrontation in September with two sports memorabilia dealers at a casino hotel room.

He's now the fourth to take a plea deal, leaving one co-defendant, Clarence "C.J." Stewart, facing trial with Simpson beginning Sept. 8.

Simpson and Stewart have pleaded not guilty to charges of kidnapping, armed robbery and assault with a deadly weapon that could put them in prison for life if convicted.

Simpson has maintained that he was trying to retrieve personal belongings and family heirlooms, and that no guns were involved.

Simpson's lawyer, Yale Galanter, said he couldn't immediately assess the effect of Monday's plea.