One of the 10 defendants originally charged in the November robbery, beating and fatal stabbing of an Olney teenager over his designer coat at the Woodley Park Metro station pleaded guilty in D.C. Superior Court on Friday.

Muquan Cawthorne, 16, of Mt. Rainier, who was initially charged with first-degree murder of 18-year-old Olijawon E. Griffin, pleaded guilty to voluntary manslaughter while armed, armed robbery and carrying a pistol without a license. In exchange for the plea, prosecutors agreed to drop the first-degree murder charge.

According to prosecutors, Cawthorne and his friends had planned a robbery spree in the Gallery Place and Adams Morgan neighborhoods.

Griffin and his friends were in the 1800 block of Adams Mill Road when they encountered Cawthorne’s group. Griffin allegedly asked whether he could buy marijuana from them. When Griffin walked with Cawthorne’s group to a secluded area, Cawthorne gave a semiautomatic pistol to one of his friends, who then pointed it at Griffin as Cawthorne served as a lookout. One of Cawthorne’s friends then removed Griffin’s black Helly Hansen designer jacket.

After the robbery, Griffin returned to his friends as Cawthorne’s group ran from the area.

Minutes later, Griffin and his friends arrived at the Woodley Park Metro station. There, they saw Cawthorne and his friends also waiting for the train.

Griffin and his friends approached the other group and tried to get Griffin’s jacket back. Cawthorne’s friends converged on one of Griffin’s friends, beating and kicking him. As the fight continued, Cawthorne left and walked away from the fight to another platform area, according to Metro security camera footage.

Prosecutors say Griffin tried to intervene as his friend was being attacked. Then, they say, one of Cawthorne’s friends, Chavez Myers, 17, of District Heights, came from behind Griffin and stabbed him in the chest.

Cawthorne faces a maximum of 65 years in prison when he is sentenced Dec. 13.

Since the attack, four teens, including Cawthorne, who were charged as adults and two teens who were charged as juveniles have pleaded guilty in the case.

A trial for the remaining four defendants is scheduled to begin later this month.