Setting up an index that has one or many values

 We are wanting to use the Universal Content Management system to archive company photographs.  We want to have some index fields, such as date and location, that are pretty simple.  The problem we have is that we want to index them by the subject of the photograph and that is where we aren't sure what to do.  For example, we want to be able to search for all photgraphs with John Doe in the picture.  There may be a photograph with just John Doe in it, but there may be also photos with 50 people in them (including John Doe).