Advertisement Team 5: Gun used to kill MIT Officer Sean Collier traced Gun once in possession of Cambridge man, sources say Share Shares Copy Link Copy

Authorities may now know how accused terrorists Tamerlan and Dzhokhar Tsarnaev obtained the gun they allegedly used to kill MIT police Officer Sean Collier, Team 5 Investigates reported Tuesday.Watch the reportStephen Silva, 21, of Cambridge, who has not been charged with any crime connected to the Boston Marathon bombing, is believed to have once been in possession of the Ruger 9mm pistol the Tsarnaevs are alleged to have used to kill Collier as he sat in his police cruiser on April 19, 2013, Team 5 reported.Silva is charged in a federal indictment with heroin distribution and possession of a firearm with an obliterated serial number, a Ruger model 95 9mm pistol.Even though the serial number on the gun was obliterated, sources told Team 5 that investigators were able to raise the number from the gun and trace it. The gun was found in Watertown after the firefight with the Marathon bombing suspects. The gun ran out of ammunition or became jammed, sources said, and Tamerlan Tsarnaev threw it away before he was killed.Silva who lives in Cambridge with his mother and sister is a student at UMass Boston. Neighbors said they saw dozens of FBI agents in his apartment Monday night.Silva is a friend of Dzhokhar Tsarnaev who graduated from Cambridge Rindge and Latin School with him in 2011.An attorney for Silva, Jonathan Shapiro, said in a statement that said, "According to news reports, law enforcement officials say it is the same weapon that was used, some months later, in the MIT Officer Sean Collier shooting. However, this has not been charged in the indictment.Shapiro said in the statement that he was in the process with meeting with Silva and reviewing evidence, and would not comment further.