An “ongoing, intense hatred between two gangs” led to angry words and then a gunshot that left 18-year-old Dwayne Graham dead on the floor of an MBTA bus, a senior Suffolk County homicide prosecutor said today.

That shot was fired by JONATHAN SANDERS (D.O.B. 7/8/89) as the Route 23 bus on which Graham was riding near the intersection of Washington Street and Columbia Road in Dorchester on the afternoon of March 30, 2007. Sanders is on trial for first-degree murder and unlawful possession of a firearm.

Assistant District Attorney Mark Lee, deputy chief of the DA’s Homicide Unit, told a Suffolk Superior Court jury that the bus was full of people – “some of them barely 13 and 14 years old” – that afternoon as it travelled along a route with no fewer than four high schools along the way.

“One minute they were laughing, joking, being loud, some being obnoxious,” Lee said. “The next instant all of them, to a person, were hitting the floor and diving for cover. They saw the body of an 18-year-old boy. But Dwayne Graham didn’t have a look of panic. He had a gaping hole in his head…. For those girls and boys, growing up took place in half a second.”

Sanders, a member of the Castlegate street gang, shot Graham dead as part of a “feud” with the rival Crown Path group, Lee said. The Route 23 bus travelled through both groups’ territories as it went from Ruggles station to Ashmont.

Graham and others boarded the bus at Ruggles. When the bus reached Washington Street, the defendant and members of his group saw Graham through the window.

“Yo, your boy’s on the bus,” one of them allegedly told Sanders, prompting Sanders and others to chase the bus on foot.

At one bus stop, Sanders boarded the bus and “in a profanity-laced challenge, demanded Dwayne Graham get off the bus. Seconds later, a shot rang out and Dwayne Graham was dead.”

Lee told jurors that they could expect to hear the contradictory testimony of confused, frightened witnesses – but also admissions that the defendant allegedly made.

“Movies and television can be Tivo’ed, paused, and rewound,” the prosecutor said. “Real life can’t be. Compare that testimony with what you’ll hear again and again and again and again: repeated admissions by the defendant that he was the one who killed Dwayne Graham.”

Testimony is ongoing before Judge Regina Quinlan in courtroom 808 of Suffolk Superior Court. Fabiola Pierre is the DA’s assigned victim-witness advocate. Sanders is represented by attorney Peter Marano.