Even if they do announce themselves it does not matter since home invaders can yell “police” to gain an advantage.
Imagine armed men break down your door in the dark and you know police have no reason to be there.
Would you put your gun down just because they say they are police?
Once again too much logic and critical thinking on your part.
Clearly the boyfriend heard it was the police and acknowledged he heard them and opened fire when they came in. Sure that’s why they dropped the charges!
Or just maybe it was even clear to the police and the DA this guy had no idea who was breaking in and was just defending himself and his girlfriend.