I remember a similar case (citation needed, don't have a link available) where a museum was destroyed by fire and the director hurried to announce that everything was destroyed.

Years later it turned out that some originals were put up for auction since they were alive and well in some private collections. Many times the original is not displayed for the public anyway and a very good copy is used instead. So someone in the museum got money for selling the originals while the copy was still on display, then got money from the insurance, with the fire covering up everything perfectly (either by accident, or for the insurance money, or to cover up the fact that the originals went missing).

Of course this would just confirm the corruption or poor maintenance arguments.