John DiFava, MIT's police chief, demonstrated Sean Collier's firearm-retention holster and recalled their final conversation before Collier's death. He later testified about Collier's character and the continuing grief among his colleagues and himself.
Law enforcementMassachusetts Institute of Technology
John DiFava
Chief of the Massachusetts Institute of Technology Police Department and a former Massachusetts State Police superintendent.
Appeared2015 Federal Trial
82 lines·8 proceedings·6 mentions
About
John DiFava testified for the prosecution on Day 31 about Officer Sean Collier's equipment and their final conversation. The MIT police chief described Collier's training and hiring, his issued .45-caliber pistol, and its retention holster. Using a holster and nonoperable training pistol marked for identification as Exhibit 691, he demonstrated three retention protections and said removing the pistol while an officer was seated would be very difficult. Exhibits 676 and 678, photographs of Collier, were admitted without objection; Exhibit 691 was used for demonstration, with no admission recorded.
DiFava recalled speaking with Collier around 9:35 p.m. on April 18, 2013, near the Stata garage exit leading to Vassar Street. Collier was in uniform in a marked police vehicle. DiFava said he never saw him alive again. The defense declined cross-examination.
Returning during the penalty phase on Day 50, DiFava described Collier's community engagement, ethics, and independence from peer pressure. He testified that grief persisted within the department despite community support. He also described questioning whether to remain a police administrator and uncertainty about wanting his children to wear the uniform. The court admitted Exhibit 1602-29, a photograph he believed showed Collier's Transit Police Academy graduation. The defense again asked no questions.
Trial Record (8)
No proceedings match this filter.