You know for years there has been a device, the magna trigger, suitable for use on S&W revolvers that prevents starngers from using a police officer's weapon on him or her. Cost about $250-300. Were I a peace officer, I'd have it on my S&W revolver, presuming the bosses agreed. A nice 4 inch .357 is a proven stopper.
Possibly bad for the rest of the folks in line. Too much penetration.