DA: It's 'Highly Likely' MBTA Officer Donohue Was Wounded By Gunfire From Fellow Officer

It is "highly likely" that MBTA Officer Richard "Dic" Donohue was struck by gunfire from another officer during a shootout with the Boston Marathon bombers in Watertown, Middlesex County District Attorney Marian Ryan said Tuesday.

Ryan made the announcement in a press conference where she discussed the findings of an investigation her office conducted into the confrontation between police and the Tsarnaev brothers on Laurel Street in Watertown just days after the 2013 bombings. Tamerlan Tsarnaev died as a result of injuries sustained during the confrontation. Ryan's office is required by law to investigate all deaths within the county.

Though Donohue was likely injured by a fellow officer, Ryan said they did not know which gun the bullet came from.

"It is impossible to know fully from which gun that bullet came, but it is highly likely that that bullet came from one of the individuals firing at Dzhokhar Tsarnaev," Ryan said.

The projectile which struck Donohue remains in his leg and cannot be removed because it could create medical complications, according to Ryan. Donohue suffered a gunshot wound to the right upper thigh near the groin area, which severed his femoral artery and caused considerable blood loss, according to the DA's office.

Following the announcement of the DA's investigation, Donohue released this statement:

While the District Attorney’s report finds it likely that I was injured by friendly fire, it does not take away from the heroic actions of those officers who ultimately prevented further acts of terror on the citizens of the United States.  Further, it remains clear that Tamerlan and Dzhokhar Tsarnaev are responsible for the firefight in Watertown.  I harbor no regrets and am forever grateful to the police officers, firefighters, and medical professionals who saved my life on April 19th, 2013.

Ryan also said the use of force that day in Watertown was justified by the many officers on the scene.

"The use of deadly force was warranted and justified based upon the deadly force with which the officers were confronted," Ryan said.

The Middlesex DA's report on the Watertown shootout was limited in scope and focused on the circumstances of Donohue's injury and whether the deadly fire by officers at the scene was justified or criminal.

Here are some additional details that were discussed at the press conference and in the report:

- It took 6 minutes and 43 seconds from the time Tamerlan Tsarnaev started firing on Watertown Officer Joe Reynolds until the time they called for an ambulance for Tamerlan.

- There were 56 shots fired from the gun the Tsarnaevs had, which was the same gun used to kill MIT officer Sean Collier.

- Officer Reynolds, the first officer on the scene, fired less than half as many times as the Tsarnaevs. He fired 27 shots.

- Two pipe bombs and a pressure cooker bomb were detonated on Laurel Street. Two unexploded pipe bombs were also found there.

- All officers who reported they had fired their weapons were interviewed. Investigators also interviewed Boston police officers who did not fire their weapons and reviewed photographs and video taken by civilians, autopsy records, police reports, witness statements and police dispatch communications.

-Of the 159 shots discharged by law enforcement 126 came from seven Watertown officers, 44 came from six Boston officers, 18 came from two State Police officers, five came from one Cambridge officer and two came from one Boston University officer.

-Donohue's weapon was fully loaded and did not appear to have been fired.

-The investigation could not identify conclusively which officers fired the shots that struck Tamerlan Tsarnaev. Ballistic evidence, however, narrowed it down to 14 officers from Watertown, Boston and Boston University.

-There were a total of 65 holes/damage to the hijacked Mercedes driven by the Tsarnaevs.

-The investigation could not determine conclusively that Dzhokhar Tsarnaev was shot on Laurel Street, due to the absence of ballistics evidence associated with his injuries. However, the report notes some of his injuries could have been sustained as he fled the scene in a carjacked Mercedes.