crazy day
first of all...police officers don't shoot just your leg. If an officer has to discharge his weapon it is to stop the suspect. not injure, not kill, stop. The best way is to aim for center mass or chest. If the suspect dies or is hurt so be it, they have been stopped. A shot to the leg wont necessarily stop them, and you must lower your sight away from their hands and down to a smaller, moving target
You need three things to fire your weapon (suspect must have): 1.Opportunity to commit deadly offense,
2.Means to cause the deadly offense, and
3.Intent to commit deadly offense.
if you are holding someone that walks away...let them do so just remember what they looked like and keep your gun on them. At least your car/lawn mower/etc isn't stolen.