The interesting thing is that I have seen multiple reports of this ( think this is is the third), but in every case, they have destroyed it, lost it, or thrown it away before hand - not given it to the police. Apple can't tell who the devices is from signals in the wild, but they can figure out who it is if someone gives them the physical device. (Apple tracks the serial number of the device, and from what I understa…
I have a feeling the interaction with the police in a lot of jurisdictions would go something like: “This person at this address tried to track me without my consent! Here’s the documentation from Apple!” “Ma’am, has the person at this address murdered you?” “No.” “I’m afraid there’s nothing we can do right now. If this person does murder you, please call 911 immediately.”
You'll probably have to spend some time explaining how it works, why it is a serious issue, and then probably be dismissed.