Stephen Silva made an initial appearance in federal court on charges related to heroin trafficking and possession of a handgun with an obliterated serial number. According to news reports, law-enforcement officials say it is the same weapon that was used ... in the MIT officer Sean Collier shooting. The 9 mm Ruger pistol described in the indictment is the same handgun that was used to kill Massachusetts Institute of Technology police officer Sean Collier during the manhunt for the bombing suspects, according to the two people, who spoke on condition of anonymity because they were not authorized to discuss the investigation. The origin of the gun was among the remaining mysteries of the investigation into the April 2013 Boston Marathon attack, in which three people were killed and more than 260 were injured when twin bombs exploded near the finish line. According to the indictment, Silva knowingly had possession of the gun, "which had the importer's and manufacturer's serial number removed, obliterated, and altered and had previously been shipped and transported in interstate and foreign commerce."