A steady stream of visitors paid tribute to MIT police officer Sean A. Collier in front of Building 32 on Friday, Apr. 19. Collier was slain near this location on Apr. 18 in his police cruiser. Ho Yin Au—The Tech May. 9, 2016 Facebook Twitter Reddit Print A steady stream of visitors paid tribute to MIT police officer Sean A. Collier in front of Building 32 on Friday, Apr. 19. Collier was slain near this location on Apr. 18 in his police cruiser. Ho Yin Au—The Tech