A Maryland man pleaded guilty for attacking two people after an argument on a Metro train.
William Nelson, 52, entered the plea in D.C. Superior Court on Thursday.
Video of the June 7 incident, which went viral online, shows Nelson punching 46-year-old Anthony Thomas on the Green Line train as it was traveling through the Anacostia and Congress Heights stations.
Thomas told FOX 5 he was attempting to stop an altercation between Nelson and two teenagers on the train.
Thomas said it began when Nelson started cursing at the teenagers after they put their feet up on the seat behind him. The dispute turned physical as Nelson hit one of the kids.
Nelson faces a maximum of three years in prison for felony assault and up to 180 days for misdemeanor assault.
Nelson will be sentenced in September.