Just curious...?

If the person making the call didn't see it happen ... How do they know for sure it did happen? Hearsay? Rumor? Gossip?

Those aren't real evidence the Police can investigate.

What was the crime... was it something private? Rape? Child molest? Child abuse? Perhaps the Police already know and are investigating and don't want 10,000 gossiping to corrupt any viable evidence. Also making up stuff that might affect the victim later. Hummm.... yeah.... so maybe only people who have first hand experience need to speak with the Police.

Does that sound possible....

But it really is hard to tell since you didn't give many details.

That doesn't happen. If the police are 1/2 as corrupt as you describe, they don't wait to be called to make bad arrests.

If that's the case, you need a lawyer to help you out since it sounds like truth of report. Don't say or write anything without a lawyer present.

Filing a false police report is something they don't take too lightly.

This happened to me when i was young, they don't arrest the caller if they don't see a crime. Usually they would investigate, but they would never press charges, unless done multiple times it could get suspicious, and if its a prank call, thats abusing the system. Don't worry about things like that.

they sue the police for millions of dollars.

curiosity killed the cat