The Vatican was the world's largest land holder and probably still is. The World bank has immense financial influence and if there's anyone with an interest in artifacts, then it would be them.
So I wonder why the 'angel' mummie is part of the Onassis fortune and not with everything else they have.

They say a person could spend a life time in the Vatican catacombs. I think it would take a lot longer than just one life time.