Suspect Jasper Spires, top left, is accused of fatally stabbing Kevin Sutherland on a Red Line train as it approached the NoMa/Gallaudet Metro station on the afternoon of July 4. (CLOCKWISE FROM TOP LEFT: Reuters; Evy Mages for The Washington Post; photo courtesy of Matt Grossman)

The 18-year-old District man charged in the fatal stabbing of a Metro passenger on July 4 appeared in court Friday on a previous assault charge and immediately began to interrupt a D.C. Superior Court judge at the hearing, prompting her to question whether he should be evaluated for mental competency.

When U.S. marshals escorted Jasper Spires into the courtroom, he smiled and at times broke into laughter as he stood next to his attorney. Friday’s hearing was in connection to a July 2 misdemeanor assault case in which Spires is accused of threatening and trying to rob a man on Wisconsin Avenue NW in Friendship Heights.

Court documents state that Spires waved an empty wine bottle at the man, who tried to walk away. Police allege that Spires then put his hands around the man’s neck and searched through his pockets. Nothing was taken, and Spires was arrested a few minutes later.

At a July 3 hearing in that case, Spires, who had no prior criminal record, was ordered released from jail pending his next hearing.

A day later, a man whom police have identified as Spires repeatedly stabbed Kevin Sutherland, 24, of Northeast Washington during a robbery on the Red Line. Sutherland was headed downtown on Metro for an Independence Day outing with friends. Spires has been held in the D.C. jail since his arrest two days later. That hearing is scheduled for July 24.

But at Friday’s hearing, as a prosecutor tried to outline the details of the July 2 assault, Spires interrupted her.

“I want to talk. What is this hearing for?” Spires asked.

Senior Judge Patricia A. Wynn told Spires that the hearing was about his assault case on Wisconsin Avenue. “You remember that case?” Wynn asked.

“Yeah,” Spires said while smiling broadly.

Then Spires interrupted the hearing again. “I don’t believe there is probable cause to hold me for the crimes I am accused of committing,” he said.

His attorney, Reginald Towe, whispered to Spires to stop speaking.

Wynn agreed to reschedule the hearing for next week, on the same day as Spires’s hearing in the murder case.

As Spires was led out of the courtroom to return to jail, Wynn asked Spires’s attorney whether a mental competency evaluation had been ordered.

“My observation is that maybe there is a potential for a screening,” she said.

Towe deferred such a decision to Antoini Jones, the lawyer Spires’s family hired to represent him in the murder case.

Court documents reveal that Sutherland, a 2013 American University graduate, was stabbed 30 to 40 times after the attacker tried to grab a cellphone tucked into Sutherland’s waistband. Police said that after stabbing Sutherland, the assailant threw the cellphone to the floor and returned to stomping the victim’s body.