A bullet that struck Boston police Officer Stephen Romano during a gunfight in May with a suspected gang member came from the gun of a state trooper, Suffolk District Attorney Daniel F. Conley said yesterday.
The trooper, whom Conley declined to identify, shot the suspect, Antonio Franklin, twice.
One of those bullets apparently glanced off Franklin and struck Romano, Conley said.
Franklin, 21, is scheduled to be arraigned today on six charges in the May 23 encounter, which left Romano with a bullet lodged in his chest. Romano is recuperating at home.
"That we know Antonio Franklin's shots missed Officer Romano doesn't change his culpability in the eyes of the law," Conley said in a telephone interview yesterday.
"The overwhelming evidence suggests that he chose to point a loaded handgun at a police officer and pull the trigger," he said. "And it is he and he alone who was responsible for Officer Romano's injuries."
Members of the youth violence task force, also referred to as the gang unit, were patrolling Geneva Avenue and Bowdoin Street in Dorchester on the night of May 23 when they noticed Franklin venturing into rival gang territory, Conley said. While they were talking to Franklin, the defendant fled on his bicycle.
Romano and the trooper pursued Franklin in their car and caught up to him. Romano got out of the car and chased Franklin on foot.
Authorities allege that Franklin turned toward Romano and shot at him twice with a .357-caliber pistol.
The officer and Franklin began to struggle when the state trooper fired at Franklin, Conley said. Authorities initially believed that Franklin had shot Romano.
In the three-month grand jury investigation that followed, prosecutors found that the ballistics evidence did not add up.
After having Romano submit to additional medical testing, including a CAT scan, they discovered that the bullet lodged in his chest had come from a .40-caliber pistol, not the .357 they allege Franklin was wielding.
Boston Police Commissioner Edward F. Davis said the bullet pierced Franklin in the right arm and the side and then apparently ricocheted off a bone in Franklin's chest and bounced into Romano.
Davis said it is common for bullets to ricochet off bones and other hard surfaces during situations as tense as standoffs between police and suspects or as mundane as practice at the shooting range.
"It was a close-combat situation," Davis said. "You don't know what a bullet is going to do when it hits the body, the bone, and other structures. We frequently see unusual trajectories in bullet situations. If you fire guns a lot, you realize that these bullets can do anything after they've hit something."
After the trooper fired his gun, Franklin dropped his weapon, Davis said.
Davis praised the trooper for his actions.
"His actions possibly saved Officer Romano's life," he said. "He took appropriate action, and the close proximity of the two individuals caused this to happen."
In a statement, Colonel Mark F. Delaney, superintendent of the State Police, said the incident "demonstrates the dangers and risks that our police officers face every day and the split-second decisions they must make. We are fortunate that Officer Romano has recovered from his wounds, and I commend the investigative efforts of the district attorney, Boston police, and State Police to accurately sort out the facts of this case for presentation to the grand jury."
Conley also said the actions of both Romano and the state trooper were "an excellent piece of police work."
"My read of the evidence here is this trooper acted to defend his fellow officer who was being fired at," Conley said. "He struck Franklin first and did his job in light of the imminent threat that Franklin was posing to Officer Romano that night."
Franklin is expected to face charges of aggravated assault and battery by means of a dangerous weapon, assault by means of a dangerous weapon, and four related gun charges in an arraignment today at Suffolk Superior Court, Conley said. Franklin, who was arraigned by the Dorchester District Court in his hospital bed the day after the shooting, is being held on $250,000 cash bail.
Efforts to reach Franklin's lawyer, Holly Clarke of the public defender's office, were unsuccessful.
Maria Cramer of the Globe staff contributed to this report. John C. Drake can be reached at email@example.com.