The 18-year-old alleged ringleader in the 1998 gang rape of a 15-year-old girl pleaded guilty yesterday in Montgomery County Circuit Court to first-degree rape and first-degree assault in the attack on the girl.

Harry Lee Williams of Hyattsville entered the pleas as jury selection was scheduled to begin for his trial. He is the fourth of the six teens charged in the case to plead guilty. The other three teens who pleaded guilty have been sentenced to life in prison. A fifth person, now 16, pleaded "involved" in juvenile court, and the sixth is scheduled to be tried in October.

The victim was waiting for a bus at the Silver Spring Metro station late on the night of March 21, 1998 when she was persuaded to accompany Williams and another man to an Aspen Hill apartment. Once there, she was raped repeatedly, sodomized and beaten by the six teens, according to a statement of facts presented in court yesterday in support of Williams's plea.

Williams, who was described by Montgomery County State's Attorney Douglas F. Gansler as "the leader of the pack" in the attack, also pleaded guilty to second-degree assault on a Montgomery County Detention Center guard whose nose he broke shortly after he was jailed in connection with the rape.

In a statement, Gansler said Williams "deserves a very severe sentence" for the "heinous" crimes and "should never see the outside of a jail." Williams faces life plus 35 years in prison when he is sentenced Dec. 3 by Circuit Court Judge Paul H. Weinstein.

The trial of the remaining co-defendant, Michael Andrease Lynch, now 20, is set to begin Oct. 4.

The girl told investigators she was approached by Williams and a second man, Muhain Ud-dien Adam, now 19, as she stood at the Metro station around 11:30 that March night. She said the men repeatedly urged her to accompany them to a nearby apartment to "chill," according to court documents.

She initially refused, but boarded a bus to the Wheaton Metro station with the two men.

They later persuaded her to ride a second bus to the Peppertree Farm apartment on Whispering Pines Drive, which Williams claimed he was renting. Assistant State's Attorney Debbie Dwyer said that the apartment actually was vacant but had been used by neighborhood youths.

"We would have shown he coaxed her into going there. He conspired to brutally beat and rape her . . . within minutes of her going to the apartment," Dwyer said of the evidence the state would have presented had the case gone to trial.

Dwyer said the evidence showed that shortly after arriving at the apartment, the girl learned that four other young men were present, and that as she sat on the living room floor, one of them suggested she go with him to a bedroom. A second man asked her to go to another room. Then both of them ordered her into a bathroom, where the assault began, court documents show.

When the victim screamed that she wanted to leave, according to prosecutors, one man struck her in the face, briefly knocking her unconscious and onto the floor.

The girl told investigators she was taken to a bedroom and raped, sodomized and assaulted for three hours. The men then left the apartment and told her to clean up the mess.

She was able to get out of the apartment and went to a nearby road where she was found by a motorist, who took her to Montgomery County General Hospital for treatment.