Three Southeast Washington men pleaded guilty yesterday in D.C. Superior Court to the Nov. 2, 1980, robbery and murder of 22-year-old local housing activist Yulanda Ward.

James Lewis Pannell, 21, the alleged triggerman, pleaded guilty to second-degree murder and robbery in conection with Ward's slaying. He also pleaded guilty to a manslaughter charge in an unrelated case.

Two others -- Mark Stoney and his brother, Jacob Stoney, 20 -- pleaded guilty to manslaughter and robbery charges in connection with Ward's death. A fourth man charged in connection with the killing, Gary Wallace Threadgill, 18, has yet to be tried in the case.

The three men each told Judge Annice Wagner that they understood the nature of the charges against them and that their pleas to the crimes could result in terms of up to life in prison.

Ward, a cochairman of the District's City-Wide Housing Coalition and a board member of the D.C. Rape Crisis Center, was a Howard University student who had taken a year's leave of absence to do community work. Friends said that she and others active in the housing group had been harassed because of efforts to stop displacment of the poor in the inner city and that Ward had received phone calls threatening her with bodily harm.

Ward's friends conducted their own widely publicized investigation of the case, which resulted in their being called before a Superior Court grand jury and asked to testify about their allegations that she was assassinated as result of her work. Prosecutors, however, gave no indication in court yesterday that the murder was anything other than part of a street robbery.

Russell F. Canan, Pannell's attorney, said the defense lawyers had investigated the conspiracy allegations made by Ward's friends but found no evidence to support them.

U.S. attorney Brooks Harrington told Wagner that Jacob Stoney had been identified as one of a group of four men involved in a robbery at 2900 Gainesville St. SE about a half hour before the Ward killing, which occurred a block away. Ward and three male companions were robbed after leaving a Halloween party. The three men, all students visiting from New Jersey, were not harmed during the robbery.

Stoney told police that three other men were with him during the robbery, Harrington told Wagner. Those men were arrested, questioned and then released. Stoney then told police he, his brother Mark, Pannell and Threadgill were the ones actually involved in both incidents, Harrington told Wagner.

Harrington said the evidence and testimony in the case indicated that all four robbery victims were told to bend over automobiles during the robbery and not to look up. Pannell placed a .41-caliber magnum revolver against Ward's head, Harrington said, and when she jerked her head back to see what was happening, the gun went off.

Wagner ordered the Stoney brothers and Pannell held without bond until their sentencing on separate dates in December and January.

Despite the guilty pleas yesterday, some of Ward's friends said they were unconvinced that the case was resolved.

Tricia Kinch, a member of the Yulanda Ward Memorial Fund established shortly after her death, said, "We still have doubts." Kinch said that, since there will not be a trial, the facts "won't ever come out, and we'll never know why she was killed or who else was involved."