If they werre Catholic, check out http://www.mtelliott.com/
and click on "genealogy." There, you can do a search and also contact someone from the company. It is a site for several different cemeteries in and around Detroit. They have always gotten back to me within a week or so.
This list of cemeteries in Detroit may also help: http://www.dsgr.org/cemeteryRecords.php