I spent a pleasant evening ridiculing CSI: Miami last night. It was a re-run, but the gist was that one CSI was at a bank for a Scenario 217A (masked crooks with Tec-9's come in and begin shooting people and things). The CSI draws his weapon and kills one crook, and the rest retreat.
In the ensuing investigation, the CSI -- a police officer who shot a criminal during a shootout -- is not only standing around jawing with his buds, but is participating in the investigation of the crime scene.
Now, I don't know much about police procedure, but it occurs to me that in an officer-involved shooting, he would likely be back at HQ being interviewed by IA and counselors and what have you, and for damn sure not be participating in the investigation of a crime scene in which he was one of the individuals involved.