A case that comes to mind on testing of DNA on bones that have been exposed to the elements is the finding of the bones of Tsar Nicholas II and his family in shallow graves in Ekaterine, Russia some 60-odd years after their murders.
They were able to determine who was who of the remains after so much time - don’t know exactly the process but do know it was from DNA matching...
You are right! I had forgotten all about that fascinating case. Thanks.