We ran into this same issue - in our case it was a video/controller board for some electron microscope - and the board itself was like 15k, and it just wasn't in the cards to upgrade it mid research project. So all dozen or so XP machines get to use the local network and that is it.
Every single other application I was able to hack/triage to get running on Windows 7 or 10 in some way or another.
I would suspect in the police dept - network security should be as concerning as physical security though - you never know when a cop turns his/her back and someone attaches a device to their XP PC or Laptop.
That said - my experience with IT law enforcement - is that its a scary world where people like to browse porn on downtime, people build all manner of in house solutions to every problem imaginable (cops are odd like that - many seem to be self proclaimed IT experts...).