A leader of the notorious Lucerne Street Doggz who allegedly shot and killed one man and seriously wounded another as the two sat on a Morton Street stoop was ordered held without bail at his Superior Court arraignment yesterday, Suffolk County District Attorney Daniel F. Conley announced.

JAMES A. WALKER, a.k.a. “GUNNA” (D.O.B. 9/9/86), of Dorchester was indicted Sept. 8 for the first-degree murder of 20-year-old Antoine Perkins, armed assault with intent to murder and assault and battery with a dangerous weapon for the non-fatal shooting of Perkins’ friend, then 19, and unlawful possession of a firearm for his role in the July 23, 2006, incident. Superior Court Judge John Cratsley ordered Walker held without bail.

Assistant District Attorney Cory Flashner told Cratsley that, on the evening of July 23, Walker was with several friends at the grave of a friend who had been killed a year earlier. After visiting the gravesite, the defendant and his friends made their way up Morton Street. Walker allegedly separated from the group and ran up to Perkins’s home. Perkins and his friend were sitting on the front steps.

“As the two were sitting on the steps, the defendant, James ‘Gunna’ Walker, approached the steps and fired shots at them,” Flashner said.

Perkins was struck in the head and his friend was struck in the neck, Flashner said. 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,” Flashner said.

A far-reaching investigation by Suffolk prosecutors in the grand jury and Boston Police homicide detectives on the street led to witnesses who placed Walker and two of his Lucerne Street Doggz gang associates in the area at the time of the shooting, Flashner said. The investigation likewise “uncovered extensive motive evidence as well as admissions of the defendant regarding his involvement in the incident,” Flashner told the court. “He believed [Perkins] was a snitch and was responsible for shots fired outside his home.”

Evidence uncovered during the course of the three-year investigation suggests that Perkins arranged a marijuana drug deal between Walker, his Lucerne Street associates, and a third party a month prior to Perkins’ death. During this alleged drug deal, Flashner said, Walker and his associates robbed the third party of two pounds of marijuana at gunpoint.

The third party did not know Walker and his associates, Flashner said, but knew Perkins and knew that he had facilitated the drug deal; he compelled Perkins to tell him the name and location of the persons who had stolen the drugs. Perkins allegedly brought the third party to Walker’s home, at which time the third party exchanged gunfire with Walker and one of his associates, Flashner said.

After this incident, “the defendant approached Perkins and asked him why he snitched,” Flashner said. “He went on to inform Perkins that as a result of those actions he was a snitch.”

Walker is represented by attorney James Budreau. Judge Cratsley told the parties to return to court on October 6 to set the tracking order for the court dates leading up to trial.