I don't know if pools are scanning the details of the miner, including the serial number, but that's the only way to know if the miner is yours.

If the owner knows the serial number, maybe the pool can provide the home IP address of the robber when the unit becomes online again.
Since before they can change the pool and username, they need to run it first and access it via the miner's IP; it would connect first to the pool.

However, having the home IP of the robber won't still guarantee that you can find them, but you can check that IP to see what ISP it use so that you can request from that internet provider who owns that IP.
Once you know who he is with his home address, you can call the police for help.