A Dorchester man admitted his role the deadly ambush that killed 36-year-old Tyrone Smith, permanently injured his female cousin, and could have killed her 8-year-old son in the foyer of a Stanwood Street building two years ago, Suffolk County District Attorney Daniel F. Conley said today.

TREVON MASON (D.O.B. 12/30/87) pleaded guilty to second-degree murder, assault and battery with a dangerous weapon, and firearms offenses for the Jan. 7, 2009, incident. He was sentenced to the mandatory term for that offense, life in prison with the possibility of parole after 15 years. Mason had initially been charged with first-degree murder.

“This is the toll of gun violence,” Conley said. “One man is dead and another begins a life sentence at 23. A woman lives with permanent nerve damage and her child bears the emotional scars of coming face to face with cold-blooded murder. It’s senseless and it has to stop.”

At the hearing in Suffolk Superior Court this afternoon, the surviving victim told Mason to “sit back and realize how many people are hurting from the gun violence in the streets and community.”

She also told Judge Thomas A. Connors that one of Mason’s rounds entered her shoulder and left fragments in her arm, which has resulted in permanent nerve damage and loss of arm function.

The surviving victim spoke through tears as she told the court in a victim impact statement that before the shooting she “always had a positive attitude about life,” but lost that attitude when her cousin’s life was taken and she and her son could have suffered the same fate but for his last heroic effort to shield them from the gunfire.

“For the first time, I have physical disorders,” she said. “I can’t do all the things I used to do. My family isn’t the same and that’s what bothers me the most … I pray that no other family goes through the tragedy my family went through.”

Another family member addressed the court and read a prose poem written by Smith’s sister and other family members as the statement from the entire family. In description of the family’s reactions on the day of the shooting, she read:

Wednesday, January 7, 2009 was typical, and merely average for most /

But as a family, a sudden black cloud covered our bodies /

and a series of mixed emotions ran through our hearts /

Who knew we would be brought together that night to hear /

“Tyrone Smith is deceased” /

Our entire world went cold and filled with many unanswered questions.

At the end of the poem, she read:

Being here today will never bring back a friend, a brother, a father

and most of all a son./

But the relief of justice being served today

will lighten the burdens that have been made.

Had the case proceeded to trial, Assistant District Attorney Ursula Knight of Conley’s Homicide Unit would have introduced evidence and testimony to show that Mason and his co-defendant, DARYL PULLEN (D.O.B. 6/20/88) fired on Smith, the surviving victim, and her young child as they entered the foyer at 96 Stanwood St. just after 9:00 p.m.

“As [the surviving victim] struggled to get her keys and open the door, Tyrone Smith – in what would be his last moments – acted as a human shield, covering his cousin and her son.”

In those same moments, Knight said, Mason ran up the steps, approached the foyer and continued to fire at the victims at close range, striking Smith multiple times and the surviving victim once in the shoulder. “The child, protected, remained unharmed,” Knight, said.

As Smith lay dying, Knight told the court, he said to his cousin, “I’m gone.”

Smith succumbed to his injuries shortly thereafter; the surviving victim was transported to Boston Medical Center, where she was treated for her injuries.

Both defendants fled the area, Knight said. Boston Police officers responded within minutes after receiving 911 calls and ShotSpotter system notifications.

Mason was found hiding in the back porch of a nearby home shortly after police arrived, Knight said, after officers observed footprints in the snow leading toward that spot from another nearby porch; under that porch, they recovered a handgun that was later found to be the same gun used in the shooting.

Pullen’s case is still pending. His trial is scheduled for July 25.

Michael Schultz was the DA’s assigned victim-witness advocate. Mason was represented by attorney Shannon McAuliffe.