I was impressed that the officer was backing away from the perp for forty seconds. Sounds like the cop did everything to avoid pressing the situation.
This cop deserves a medal for his outstanding performance. He quickly assessed that he was dealing with a mental and went above and beyond to avoid a self defense shooting until it could no longer be avoided. And, once shooting became necessary, he fired only a single shot.
The young mans family should thank this cop for the patience he displayed.