Handicapped parking fraud?

At the establishment I work at all sorts of customers love to park in the handicapped space. If they appear fully able-bodied I let them know that they are parked in a handicapped spot, to which they always reply "Oh I have a handicapped sticker." I don't want to be impolite in case they actually are handicapped. Occasionally someone will say it belongs to their mom or something, in which case I will ask them to move their vehicle to a different space. This kind of inconsideration and unneedful selfishnish is appalling. I myself am disabled, but my legs work just fine and I would never dream of parking in a handicapped space. I have friends who are missing a limb and walk on a prosthetic, and even they park in a regular parking space and walk the short distance to the door! I know there is a website where I can log their plate and handicapped placard #s, and hope someone checks up on it. My question is, is there anyway that I could determine on the spot whether or not this person is allowed to park there? A website, I could enter the placard # etc. Or the police department, if I called them with the individual's and vehicle's info, would they take care of it? Please, someone tell me that such a thing exists.