does a life estate exist if there is no document that describes it?

Deceased received oil company shares from parents in the 50s (not life estate) Deceased's acct was designated as a "life estate" years later for unknown reason by unknown entity. No life estate document can be found after thorough search and familly has no knowledge. Oil company suspended account and refuses to issue division orders or pay out accummulated $ until beneficiary information is provided (ie, copy of life estate if found). this has gone on over a year now.