I'm not a sworn LE officer or work for any public safety/homeland security agencies at this time but I can honestly tell you; 911 calls or formal notifications have little or no bearing on a LE patrol deputy, state trooper or officer's behavior-mindset in a critical incident.
Working cops like to have a beginning a middle and a end.
Who calls 911 or what goes on at a scene are just pieces of the big puzzle.
I'd add that in a event, either as a witness or active part, stay calm, do not use slang, humor or profanity. Speak slowly and clearly. DHS calls this method; plain talk.
Ive seen many many patrol deputies, agents & police officers shut down immediately when dealing with victims or crime scenes where people wig out or are in a panic.
It can be tough but if you want the law on your side, be level headed & open to the real way the US criminal justice system works.
PS: I'd add here that in many locations, 911 calls are routed to a regular police dispatcher or emergency ops center. These specialists may also take radio calls, texts-soc media updates, faxes and non-emergency calls too.