It may involve someone on the outside helping the perp so naturally they do not want to show their hand as it is an on going investigation. Pure speculation on my part.
They've admitted the suspect shot them both to death with ONE of the deputies guns. This wasn't planned. This was done on moments notice when the suspect saw a clear weak link and was able to disarm one of them. This was sudden and quick.
And by the way, the courthouses I’m familiar with are loaded with internal/external cameras. Especially in areas where prisoners are being dropped off/picked up on a regular basis.