As a prospective buyer, the DOH might be able to give you more details about the charge. Or, you could just ask the seller.
Googling the address might be able to help if there was a crime on site, but is less helpful re: suicides, natural deaths, mercury spills, and meth labs.
I think the main issue is who is going to pay the outstanding fine: The buyer or the seller?
...at this point, I'd like to believe that whatever needed to be cleaned up, was.
Lots of houses have histories.
The DOB publishes a list of work that does, and does not, require a permit:
...if prior work was completed without permits, some consequences can be levied on subsequent owners.
(but you should rely on a knowledgeable lawyer for the details)