MIT has identified the police officer killed in the line of duty on Thursday evening as Patrol Officer Sean A. Collier, 26, of Somerville, Mass. Collier had served as a member of the MIT Police since Jan. 9, 2012, following service as a civilian employee with the Somerville Police Department. He was single and a native of Wilmington, Mass. “Sean was one of these guys who really looked at police work as a calling,” said MIT Police Chief John DiFava. “He was born to be a police officer.” Collier was shot Thursday evening following an altercation at the corner of...