Ok, I saw this on TV today.
There was a guy who was pretending to be a vet. Someone brought in their dog for some kind of surgery (missed the details, sorry. If anyone else knows this, please fill in) and after the surgery was done, the guy came out and said the dog wasn't doing so well and that he'd have to be put down.
The owner asked to see the dog and found him in TERRIBLE shape. No after-care at all, his muzzle was still bloody and he looked miserable.
Needless to say, the police was called. Since they had no evidence that the "doctor" was responsible, they needed proof.
Enter: the undercover cat!
A woman (the one who was on the show) volunteered her cat to go under cover. She was allowing the cat to be taken to the man for a fix, since that was needed to be done anyway.
The doctor took the money and agreed to the procedure. He took the cat and walked out of the place and was met in the hallway by the real back-up cops.
The cat now wears a small PD badge
Hooray for undercover animals!!