Article Photos: Slain MIT officer memorialized at campus service 2/12

Police officers arrive to a memorial service for fallen Massachusetts Institute of Technology campus officer Sean Collier at MIT in Cambridge, Mass. Wednesday, April 24, 2013.  Authorities say Collier was killed by the Boston Marathon bombing suspects last Thursday, April 18. He had worked for the department a little more than a year.  (AP Photo/Elise Amendola)