A new report recounts in chilling detail how the Boston bombing suspects were hoping to add to their arsenal when they allegedly murdered young police officer Sean A. Collier with five gunshots.

Collier, 27, was about to start a new job with the Somerville Police Department when he was killed.

Surveillance camera video shows the two suspects creeping up on Collier’s squad car from behind.

He was shot five time, police said. Two of those rounds were to the head.

‘He didn’t stand a chance,’ DiFava said.

The suspects allegedly tried to take Collier’s gun but were unable to unlock it.