If this is seriously only about free-killing, the solution is simple.
Provide more incentives to the police force, and lower support to criminality. There's many different ways you could do this...
-Raise the fixed price for weaponry
-Deny payment rights to criminals
-Provide the police force with more incentives
In other words, if the administration itself supports free-killing, then the only thing you can really do is propose changes to the functioning system itself.