Two 16-year-olds charged in the Nov. 17 killing of an Olney man at the Woodley Park Metro station pleaded guilty Tuesday in the juvenile branch of D.C. Superior Court to lesser charges of armed robbery and other offenses.

The plea deals came two days before the teens were scheduled to be tried in the case. The teens, whose names were not released because they were charged as juveniles, pleaded guilty to various counts — including armed robbery, felony assault and assault with a deadly weapon — in connection with the robbery and fatal stabbing of Olijawon E. Griffin, 18.

To date, six youths ages 16 to 17 have been charged as adults in Griffin’s killing.

Authorities allege that the teenagers robbed Griffin at gunpoint of his designer Helly Hansen jacket, hat and iPhone in an alley near the 1800 block of Columbia Road NW. Minutes later, Griffin and some of his friends walked to the Woodley Park Metro, where they saw the teens who had robbed them. At the Metro, authorities say, the teens attacked Griffin and a friend, and during the fight one of the teens fatally stabbed Griffin.

The juveniles’ plea deals are the first convictions in the case. A trial for the six other teens is scheduled for September. It was unclear whether the juveniles’ deal required them to testify for the prosecution at the trial of their friends.

The juveniles, who were 15 at the time of the killing, are scheduled to be sentenced April 11 and are being held at the Youth Services Center, which is operated by the District’s Department of Youth Rehabilitation Services.

A ninth person was also charged this week in connection with the attack. Greg Whittaker, 18, of Hyattsville was charged with armed robbery of Griffin’s friend. At Whittaker’s preliminary hearing Tuesday, Assistant U.S. Attorney Justin Dillon told the judge that his office also planned to charge Whittaker with felony murder in Griffin’s death.

During Whittaker’s hearing, Carter Adams, a D.C. homicide detective, testified that Whittaker was arrested March 5 because he, unlike many of the other teens who were arrested shortly after Griffin’s death, gave police a fake name when he was questioned. Whittaker also told police at the time that he was only a witness to the attack and was not involved.

During the hearing, prosecutors played a Metro security tape for D.C. Magistrate Judge Frederick J. Sullivan. Adams said the tape showed Whittaker as part of the group in the fight with Griffin and his friend.

Whittaker, according to charging documents, had a folding knife at the time of the attack. At one point, prosecutors said, Whittaker pointed it at Griffin when Griffin, who was unarmed, tried to help one of his friends who was being attacked by Whittaker’s friends.

During the fight, one of Whittaker’s friends, Chavez Myers, 17, of District Heights, allegedly plunged a knife into Griffin’s chest. Myers has been charged with the most serious offense — first-degree, premeditated murder.