I haven't thought about it and this is just an off-the-cuff idea - if there is no payout for an APD member killing a suspect, take out the pardon from it as well.
In role play aspects, this would not make sense, but would at least prevent "free pardons" by barricading yourself inside a locked home or putting yourself in an unreachable location and forcing the officers to kill you.
Just read the edit. Cool.
Edit: So I think there could be a misconception that officers use lethal ammunition for the quick payouts. The payouts for using lethal ammunition are abysmal as they are currently, which is good because you should not be rewarded, as an APD officer, for killing suspects. Your job is to bring them in and question/process them (where possible).
It wouldn't be a huge change on the cop side of things, only the civilians.
Out of curiosity though, why not just remove the payouts and pardons? Why is it between those two options, being able to only allow a revive from an APD officer or reducing the force respawn timer?