It is very possible for a bullet not to travel through your head or body depending on the caliber of the gun and the shot being used. For example, police carry hollow point bullets for this reason. Hollow points mushroom out upon impact so it won't travel through and hit an innocent person.
Its very well possible the gun was not found on him during a search because some officers get into a routine with their job from doing it everyday that unfortunely makes them sloppy. I've seen knives missed, razor blades in the waist area of pants, and other small things missed before. A person that is detained and awaiting interrogation usually would not be in handcuffs because they have been through processing and should of been searched all the down to the soles of their shoes. Even the shoe laces are taken out to prevent a person from hanging theirselves or choking someone else. All jewelry should be taken also, the only thing a person should have is their clothing and shoes with no laces. On the street when arrested, the officers should of searched his person, removed any weapons, jewelry, and anything else in his pockets or where ever else. Then in booking he should of been searched again. Technically, everytime the prisoner changes hands from the arresting officer to transporting offier to booking, etc., the prisoner should be searched in case something was missed. If believed to have something somewhere else, a cavity search would be performed by a doctor. And now your probably wondering why I know this stuff in detail...I USED to be 5.0 and these procedures are used where I live. They may vary a little from state to state, but this situation is very well possible. I'm not saying its real or not, I haven't heard of this story, so I don't know any details on it.
Another thing, why would the officer react differently in this situation? He doesn't know the guy, the guy killed an officer, and the guy would just await trial and go through appeals for the next 20 years before any serious punishment would be handed down. The man just did to himself what the other officers would of liked to have done to him for what he did. I might sound harsh, but he took the easy way out and he deserved a bullet to the head.
So with my :2cents: put in, I'm prepared for the :smash: to begin on my views.