I think the police are in shock that one of theirs committed this crime, and are therefore releasing all the information they have.
I also think they are very concerned about the security aspect. The accused was a fire arms officer in the Diplomatic squad, If he has done what he has been accused off, supposing he had instead chosen to whip out his gun at work and shoot or attack someone he was meant to be guarding
The head injury is self-inflicted, I think. In the past, he probably would have been 'done over' in the station, for the nastiness of the crime and him being one of them, but nowadays, they must very clearly be seen to be handling him with kid gloves, possibly that is why he inflicted his his injury.
It sounds to me, taking into account the separate charge against him, that he may have had some kind of breakdown or psychotic episode.