A Dorchester man gunned down a fellow gang member because the victim was “a snitch” who led an angry drug dealer’s associates to the defendant’s home after a drug rip-off, a Suffolk County homicide prosecutor said in closing arguments this morning.

Assistant District Attorney Edward Krippendorf said JAMES “GUNNA” WALKER (D.O.B. 9/9/86) shot 20-year-old Antoine “Pun” Perkins dead – and nearly killed Perkins’ friend – on July 22, 2006, because Perkins had arranged for some of his Lucerne Street Doggz associates to purchase two pounds of marijuana from a drug dealer they robbed instead. When the dealer told her boyfriend, prosecutors say, the boyfriend confronted Perkins and Perkins led him and others to Walker’s home.

Walker called Perkins “a snitch, and not just that day,” Krippendorf said. “He didn’t let it go. You heard that in the days and weeks afterwards he continued, he pursued that.”

Krippendorf said a “gun battle” broke out between Walker’s associates and the men who had accompanied Perkins to the house. Nobody was hurt and the two parties scattered.

“The motive that this defendant had was not tepid in any way, shape or form,” Krippendorf said. “That motive that you heard about in this courtroom was real, and it was violent.”

On the night of Perkins’ murder, prosecutors allege, Walker and a few of his associates were in the area of Morton Street, where Perkins lived and was sitting on the porch with a friend. Walker allegedly went by himself to the side of Perkins’ house and fired at the two victims. Perkins was mortally wounded by a gunshot to the head and his friend was struck in the neck.

Boston Police officers and emergency medical personnel arrived on the scene and transported the victims to Boston Medical Center. Although Perkins’s friend survived, Perkins succumbed to his injuries shortly thereafter.

After hearing gunshots, Krippendorf said, one of Walker’s associates saw the defendant as he jumped over a nearby fence.

“It’s a face to face confrontation,” the prosecutor said.

That witness was subsequently interviewed by Boston Police homicide detectives and was able to pick the defendant’s photograph out of an array, Krippendorf said.

“He knew what he saw that day,” Krippendorf said.

In addition to the identification, Walker confessed his “dirty deeds” to a friend who had just gotten out of jail, Krippendorf said. That friend also testified in court “to great personal cost to him – he had to relocate, get out of the area, abandon his friends…and is now labeled a snitch like Antoine Perkins.”

Krippendorf reminded jurors to think about the defendant’s actions and his statements to police in the days and weeks following the shooting.

In an interview with police detectives, “he denied that he was in the area of Blue Hill Avenue and Morton Street on the night of the killing,” Krippendorf said. “He’s evasive and lies to police throughout the conversation.”

In July of 2009, after an extensive investigation by Boston Police homicide detectives on the street and Suffolk prosecutors in the grand jury, Walker was arrested and charged with first-degree murder and armed assault with intent to murder.

“Hold James Walker accountable,” Krippendorf told jurors. “Find him guilty.”

Katherine Moran is the DA’s assigned victim-witness advocate. Walker is represented by attorney James Budreau. Judge Raymond Brassard is presiding in courtroom 815 of the Suffolk Superior Court.