What good is the POA?

Also, the police will not get involved in property disputes - they are civil matters. When I was an officer, we were often needed to be on scene for victims of domestic violence so that they could pick up personal belongings. we would only allow them to get a few clothes and medications and it had to be stuff that was obviously theirs (example:women picking up women's clothing, men picking up men's clothing)

We made it clear that if there was any dispute over property rights of an item, it would have to remain in the residence and the could file for a court order.

Even if your father showed up there in person, the officers would likely not allow him to take any items that were in contention.

The proper recourse is for your father to file for a writ of replevin. There is a good chance that your POA does not cover civil actions.

Having a POA does not override tenants' rights. A tenant does not have to admit a landlord, privacy is still theirs. If the place was rented furnished, they have an expectation for it to remain so furnished. Go see your lawyer and learn about tenants' rights and proper eviction procedures.