Big ups for actually looking into this btw.
Honestly, as I cop I know I play a lot more recklessly and am not too pissed about dying, I don't lose anything. The thing is, it makes the game a lot more enjoyable when you're scared to die, you care about your character. The most logical solution I can see for this is just increasing the death timer of cops. Maybe make it 10 minutes from death to respawn, plus the 5 minutes of NLR. If I had to effectively wait 15 minutes between each death, it would not only decrease the "zerg" but it would make cops more scared to die. It's much less of a game play impact than decreasing gun prices and shit.
I think it would work quite well to give the cops a 10 minute death timer, instantly making it harder. Another area would be to not allow the paying of confiscation money whilst you're dead or have NLR, if you die in a raid, you can't get paid for it because you don't deserve it. Decreases the money cops get from raids if they cant survive and just overall making deaths meaning a lot more for the cops, hopefully adding a bit more balance for your calculations and all.