Sean Collier

Sean Collier's killing while serving as an MIT police officer was examined through police, surveillance and forensic testimony during the guilt phase. Sergeant Clarence Henniger described finding him shot in his cruiser on April 18, 2013, helping provide emergency treatment and securing his firearm, which remained holstered despite a lowered retention latch. Matthew Isgur authenticated MIT surveillance showing two figures approaching the cruiser and leaving along the same route. Forensic pathologist René Robinson identified gunshot wounds to the head as the cause of death and homicide as the manner; she could not determine the order of the head shots. Jurors saw autopsy photographs, but the court excluded them from public screens. DNA analyst Jennifer Montgomery reported profiles matching Collier from exterior samples of two white gloves and stains on a Honda Civic key card. On the handgun counts involving his death, the jury found that Tsarnaev caused the death through murder or aided and abetted another in doing so.

Collier also featured in penalty-phase victim-impact testimony. His brother Andrew described their closeness and the continuing loss at family gatherings. His stepfather Joseph Rogers discussed Collier's ambition to become a police officer, community service and the effects of his death on family members. MIT police chief John DiFava described hiring Collier, his engagement with the campus community and the department's continuing grief.