A Suffolk County homicide prosecutor recounted an alleged murderer’s post-shooting bravado today as a Roxbury man went to trial for the homicide of 28-year-old Senai Jamaal Williams.

“What does a man say after he kills another man?” Assistant District Attorney Jennifer Hickman asked jurors rhetorically this morning. “If you’re JAMES ALLEN, you’ll say words to the effect of, ‘don’t bring a knife to a gunfight.’ Those are the words you will hear Mr. Allen said after shooting and killing Senai Williams.”

Allen (D.O.B. 8/30/88) is charged with first-degree murder, unlawful possession of a firearm, unlawful possession of a large capacity feeding device, and unlawful possession of ammunition. His co-defendant, SHAWN BUCHANAN (D.O.B 10/23/79) is facing the same gun charges and an additional charge of accessory after the fact to assault and battery with a dangerous weapon; he is not charged with Williams’ slaying.

Hickman told the court that on 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.

“He started this whole incident,” Hickman said of Stephens. “He sets it in motion. You will hear that there was a confrontation between Senai Williams and [Buchanan’s brother]. There’s some pushing, there’s some shoving.”

Eventually, the brother left the hallway and went across the street. When he got outside, he saw a female resident of the same building looking out the window. He cursed at her, Hickman said, sparking an altercation in which she punched him in the face. Williams became involved and separated the two.

Hickman said that as a result of the altercation, the brother called Buchanan, who went with Allen to Homestead Street. Allen armed himself with a “Turkish semi-automatic firearm that cannot be legally carried in the state of Massachusetts. It was a firearm that was loaded with hollow point bullets,” Hickman said.

After they arrived on Homestead Street, Buchanan called up to the residents of the third floor apartment to come outside. Williams and the female occupant went out to talk to him. The woman knew Buchanan and they “used to party together,” Hickman said. Meanwhile, Allen stood off to the side near 23 Homestead St., observing the scene.

What began as a relatively calm conversation turned less so when “Mr. Buchanan became agitated,” Hickman said. Allen suggested that the two men “shoot the fair one,” Hickman said, which is slang for “fight without weapons,” she told jurors.

Buchanan and Williams agreed to a fight – one where “most of the blows aren’t being landed,” Hickman said. “They’re backing up. They’re going forward. There’s no contact.”

Buchanan and Williams were the only ones involved in the altercation, she said. At some point, a knife was introduced, but witnesses gave differing accounts about who introduced the knife to the altercation, Hickman told the court. No one was injured, but within seconds, Hickman said, Allen pulled out his firearm, aimed it at Williams and fired one shot. The bullet struck Williams in the abdomen, tearing through his internal organs and causing life-threatening injuries.

In the aftermath of the shooting, Hickman said, Allen fled the scene and Buchanan was seen running into 23 Homestead St.

Boston Police officers and paramedics responded moments later. 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. Detectives tracked down both men at the Bromley Heath housing development and, after speaking with both men, placed Allen under arrest.

He was arraigned in Roxbury District Court on Nov. 19, 2010. On Feb. 1, 2011, a Suffolk County Special Grand Jury indicted both Allen and Buchanan for their alleged roles in the homicide.

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