A D.C. Superior Court judge ordered a mental health exam for the suspect in the July 4 stabbing on a Metro train.
Jasper Spires, 18, walked into the courtroom Friday with a big smile on his face and he continued to smile as prosecutors laid out evidence against him.
Some of the evidence placed Spires in the NoMa-Gallaudet Metro station the day of the murder.
Prosecutors said the suspect's DNA was found on a pair of camouflage pants that fell out of a backpack as the alleged killer ran from the station.
Detective Gabriel Truby also told the court that a knife found in a trash can inside the station had the blood of the victim on the blade.
Prosecutors played a series of videos for the court, including one they claim showed Spires briefly stopped near the trash can where the knife was found.
Police said they also found a health insurance card with Spires' name on it inside a backpack dropped by the suspect as he fled the station.
But Spires' attorney argued police and prosecutors have not yet proven the man in the videos is Spires.
"None of the witnesses have been able to identify him, none of the witnesses who were on the subway have identified my client as being the perpetrator," said attorney Antoini Jones.
Spires is accused of viciously beating, stabbing and stomping on Kevin Sutherland as the two rode a Red Line train from Rhode Island Avenue to NoMa-Gallaudet on July 4. Police said the attack began over a cell phone.
"I think we all lose a piece of ourselves when we see something so brutal like this," said the victim's cousin, Anita McBride.
Sutherland was a graduate of American University. The 24-year-old decided to stay in the city and began a career working as a political digital strategist.
Spires is due back in court August 28 after his mental health exam is completed.