A Superior Court jury this afternoon rejected a Roxbury man’s self-defense claim and found him guilty of murder for the fatal shooting of a 28-year-old Senai Williams on Homestead Street, Suffolk County District Attorney Daniel F. Conley said.

Jurors convicted JAMES ALLEN (D.O.B. 8/30/88) of second-degree murder, unlawful possession of a firearm, unlawful possession of a large capacity feeding device, and unlawful possession of ammunition for the Nov. 18, 2010 shooting of Senai Williams. Superior Court Judge Patrick Brady scheduled sentencing for tomorrow morning.

“When a man brings a loaded handgun to a fight he instigates, then points it at another man and shoots him in the back when he seems to be winning, that’s not self-defense,” Conley said. “That’s murder, and the jury rightly called it that.”

Allen’s co-defendant, SHAWN BUCHANAN (D.O.B 10/23/79) was acquitted of those same gun charges and an additional charge of accessory after the fact to assault and battery with a dangerous weapon; he was not charged with Williams’ murder.

Hickman proved that on the afternoon of Nov. 18, 2010, Buchanan’s brother was smoking marijuana with friends in the hallway at 20 Homestead St. Williams, who lived on the third floor of that building, went downstairs and asked Stephens to leave, but he refused. This led to a confrontation between the two men, where there was some pushing and shoving.

The evidence showed that Buchanan’s brother left the hallway and went across the street and cursed at a woman he saw looking out the window, prompting her to come outside. During the altercation that followed, she smacked him in the face. Williams separated the two.

After a call from his brother, Buchanan went to Homestead Street with Allen. Allen had armed himself with a Turkish semi-automatic firearm loaded with hollow point bullets. Buchanan called up Williams and others, who went downstairs to talk to him.

Allen suggested that Williams and Buchanan’s brother settle the issue with a fistfight. At some point, however, a knife was introduced. No one was injured, but within seconds Allen pulled out his firearm, aimed it at Williams, and fired one shot.

That bullet entered through Williams’ back, striking him in the abdomen, tearing through his internal organs and causing life-threatening injuries. Allen fled the scene, but only after saying, “Don’t bring a knife to a gunfight.”

Boston Police officers and paramedics responded to the scene. Williams was rushed to Boston Medical Center where he was pronounced dead. Witnesses provided homicide detectives with descriptions of the suspects and additional information that led them to identify Allen and Buchanan as being involved in the incident. During the execution of a search warrant on 23 Homestead St., officers recovered the firearm that was used to shoot Williams secreted in a closet in the basement. Prosecutors had argued that Buchanan placed it there after the shooting but before he knew Williams had died.

Katherine Moran is the DA’s assigned victim-witness advocate. Allen was represented by attorney James Budreau, and Buchanan was represented by attorney Edward Wayland. Proceedings were before Judge Patrick Brady in courtroom 815 of the Suffolk Superior Court.