What happens when u have the police serve HP with a subpoena?

My HP laptop was stolen last week. I called the cops right away and gave them the serial number. Then I called HP to see if there was anything they could do,they said to have the PD serve HP with a subpoena. What does this do? I have a feeling the people downstairs had something to do with it cause my door, which is right ny theirs, was unlocked and the laptop went missing the same night.can the police search their apartment with the subpoena?