The person who gunned down 15-year-old Soheil Turner on a busy weekday morning did so “without warning, without hesitation and without provocation,” a Suffolk County homicide prosecutor said during opening statements this morning.

“As Soheil Turner stood outside the Nunez Market armed with nothing but his backpack and the honey bun he was eating at the time,” Assistant District Attorney John Pappas said, “this other person approached him from the bus stop diagonally across the street. After approaching Soheil Turner, this person engaged him in conversation right outside the Nunez Market.”

That person was later identified as XZENIYEJU CHUKWUEZI (D.O.B. 4/4/91), the man charged with first-degree murder and unlawful possession of a firearm for his role in the fatal shooting at Adams and Dudley Streets at approximately 7:00 a.m. on May 7, 2009.

Pappas told the court that after approaching Turner, the defendant “produced his .380 semi-automatic handgun out of his right hand pocket and shot the defenseless and unsuspecting Soheil Turner in the back of the head.”

The bullet tore through Turner’s skull and brain, killing him.

“The trauma was both massive and fatal,” Pappas told the court.

Following the shooting, Pappas said, a witness saw Chukwuezi run up Adams Street to the backyard of his Forest Street home as “Soheil Turner lay on the ground, his life literally ebbing out of his body from the fatal gunshot wound to his head, his half-eaten honey bun on the ground in a pool of his own blood.”

It was during the course of “a very intense and very direct investigation” starting the morning of the shooting, that Boston Police homicide detectives together with Suffolk prosecutors were able to identify the shooter, and arrested Chukwuezi a week later, Pappas told the court.

Pappas also told the court that in addition to witness testimony, jurors would have the opportunity to view security camera surveillance videos that, unbeknownst to the defendant, “were capturing his every move including up to, during, and just after the shooting.”

Pappas told jurors that there was no one else in that video who could have done the shooting.

“One person, one gun on May 7, 2009,” he said.

Catherine Rodriguez is the DA’s assigned victim-witness advocate. Chukwuezi is represented by attorney John Moss. Proceedings are ongoing before Judge Linda Giles in courtroom 806 of Suffolk Superior Court.