Just tell the police that as you were waiting in line, the lady wouldn't stop complaining about how overweight and lazy the local cops are. Tell the police that you couldn't take her bad mouthing law enforcement any longer so you placed more than enough money on the counter and left.
Never talk to the police. If they come to your door politely say "I refuse to answer any questions on the grounds that it may incriminate me" and politely close the door. Don't answer it no matter what they say.
you'll probably start seeing helicopters following everywhere you go.