When bomb truck is parked behind the tree you actually see the side of the truck say State Police referring to the Secretary of State Police. On the containment vessel says Chicago Police Bomb Squad.
When Dawson comes into the squad meeting room and announces that Colin's death was not a suicide (no traces of gun powder on his hands) but a murder instead, the evidence board behind him already has the word "suicide" crossed out and the word "murder" is written beside it.