Passcode before turning off

Ok guys, I live in a 3rd world country and we a have a lot of problems with criminality. So in order to retrieve a stolen phone through "find my iphone", the phone needs to be on.

My idea is: Enforce a passcode before turning off the iphone

This would prevent the iphone from being turned off and we would be able to track it down with the help of law enforcers

Im pretty sure this is an easy fix and would be greatly appreciated