Look in filing cabinet or wherever you keep car titles, marriage certificate, and legal papers. I feel that he removed it from typical location to carry on business, and chucked it in a place that the other paperwork pertaining to that mission, were flopped. Not male bashing, but Men don't think to "file" anything back in it's original location. It's why they get wives.
What were the last three reasons for him do dig out the document, and where did the papers pertaining to those reasons, end up getting chucked?
Car titles? Anything pertaining to secretry of state? Court objectives? (like custody hearing or divorce paperwork, etc.) Passport? Registering for classes? financial aid? Work insurance or retirement information?
Look in any folders that have information for whatever he needed that paper for.
Also, is there a possibility that paper would be in his parents home?
Blessings,
Rebecca