Thanks for the suggestions. Maybe an answer is in one of the places you mention.
Missouri has that same inexplicable "privacy of the dead" policy to deny relatives of anyone who died under state juridiction of needed and wanted medical information which would be available had the death not occurred on state property. Odd that protection is exercized strongest when no value or good can conceivably come of it to anyone, isn't it?
I won't know until I can check further, but if this is a match for my great grandmother's missing sister, her case might have proven to be a lead to what might have happened to her grandmother who disappeared in the early 1840's, never appeared anywhere on 1850, 1860, or 1870 censuses and was believed to have died young until she inexplicably turned up in her son's home on the 1880 census. That grandmother gave birth to my great, great grandmother [mother of Mary Ellen (Tipton) Twitchett] in Maquon, Illinois in 1843; her daughters were taken to Iowa with a family not known to be related to them in 1844 and reared and married there; and her husband remarried in Ste. Genevieve, Missouri a couple of years later. Thorough searches of every imaginable spelling of her name in those three states and others have never produced any lead to where she was for the about 37 years she was missing.