BOSTON (WBZ-AM) -- An 18-year-old man was arraigned Tuesday in East Boston District Court in the shooting death of a Boston man.
Thorus O'Brien of Brockton was ordered held without bail. He is charged with the murder of Duncan Ketter, 21, of Boston.
Related: Police Investigate Fatal East Boston Shooting
Prosecutors say O'Brien shot and killed Ketter in the back of an SUV around 4:45 p.m. Sunday near Orleans and Marginal Streets in East Boston.
Friends and family of Ketter listened in the courtroom as prosecutors described the shooting.
Prosecutors said it was a marijuana deal that turned into a robbery--and then into murder.
After the shooting, prosecutors said O'Brien pushed Ketter out into the street. Ketter later died at an area hospital.
One friend of Ketter's told WBZ NewsRadio 1030's Carl Stevens that the suspect and victim knew one another.
"They were cool at one point, but I guess stuff happened, and it's sad to see that," she said.
Ketter was in the news in 2014 when he helped rescue a man who had fallen into the pit of the subway tracks at North Station.
"Yeah, he rescued someone on the train," his friend said. "He went to the Maury show, got two tickets to the Super Bowl to see the Patriots."
She said this shooting happened "out of nowhere."
O’Brien, who has a juvenile record that includes assault and battery with a deadly weapon (a rock), was arrested on Monday.
Police are still investigating and have asked for the public’s help with any information related to this incident by calling (617) 343-4470 or the CrimeStoppers Tip Line at 1(800)494-TIPS or by texting the word ‘TIP’ to CRIME (27463).
WBZ NewsRadio 1030's Carl Stevens reports