If you are involved in an incident, call 911 immediately after the incident and report that there has been an incident. Tell the dispatch where this took place and whether there is need for an ambulance.
Then...say nothing else. When the officers arrive, invoke your 5th amendment right and request a lawyer be present before questioning.
Otherwise, you'll regret running your mouth.
“A police officers job is first and foremost to investigate and collect evidence for possible prosecution.”
Unfortunately, that’s not really his first priority, however, I get what you are saying because that’s what they do anymore.