I don't think reporting this to the police will do anything.
Last year my son's band had their van stolen in Portland and the police did nothing. I mean literally NOTHING.
The van had an Airtag, so he could follow where it was going. They called the police numerous times and reported it stolen, with its current location, but never got a call back from an officer. After a few hours of calling, someone from the police let them know that they couldn't do anything, that it wasn't an emergency, and that he should consider the van gone and report it to his insurance.
I suspect that's the answer the Portland police will give you, if they ever actually respond to the complaint.
In the end, my son's band and another group on tour with them grabbed baseball bats, tracked the van down and stole it back from some meth heads.
If Mike had any of my books and refused to return them I'd hire a "Private Investigator" to go retrieve them.