You have it backwards—serial killers aren’t deterred by good policing because they are motivated by a psychological need to kill. The random kid who gets pissed off is exactly who is more likely to be deterred by the knowledge they will likely just get arrested.

There are confounding variables in terms of how likely they are to be charged and how severe the sentencing is, but you really quickly hit diminishing returns there. Otherwise, the deterrence effect of the certainty of getting caught is one of the most consistent findings in research on crime reduction.

And good policing does result in more evidence. One of the factors that makes it hard to catch killers is distrust between the police and the community, which means people are less likely to come forward to help the investigation. Again, there is some really solid data demonstrating this over time. Heck, there is even some research showing that better policing directly reduces murders—one reason that beefs get so bad is distrust in the formal system to deliver justice, so people take matters into their own hands.

The whole point is that it isn’t simply “more” cops, but better cops. Adding more cops when the cops are shit doesn’t help and can hurt.

And, sure, I agree that reducing the number of guns would be great too, but sadly I suspect we have far more policy control over the cops. And how do you expect to remove illegal guns from hands without more and better policing?