Good info from other posters.  Depending on how old the mortgages are, they might have MERS Mortgage Identification Numbers (MINs).  It is an 18 or 19 digit number, usually on page one.   You can go to https://www.mers-servicerid.org/sis/, or call (800) 646-6377 and follow the menu options.  We put this info on our commitments now because it is the best way I know of to make sure the payoffs are done correctly, and/or to get releases years after the fact.