Article Photos: Slain MIT officer memorialized at campus service 10/12

Massachusetts Institute of Technology visiting scientist Tom O'Dwyer, of Arlington, Mass., places flowers at a makeshift memorial to fallen MIT police officer Sean Collier on the school's campus, in Cambridge, Mass., Wednesday, April 24, 2013. Collier was fatally shot on the MIT campus Thursday, April 18, 2013. Authorities allege that the Boston Marathon bombing suspects were responsible. (AP Photo/Steven Senne)