Pretty unbelievable. One of those things you would guess as false and yet wonder if it’s just odd enough to be true.
Imagine you found (by some long chain of events) a message in a bottle from a long forgotten relative. Just as in this case, written as he or she was dying then left to be found. You could create a whole story about how the message was left but lost and wandered around for centuries only found by some odd mixture of events. It wouldn’t need to be a message in a bottle. It could be found in a time capsule. It could have been under the floor boards of an old house being demolished. So many options to choose from or invent.
Write the story, from start to finish, all the places and people who became involved in that old message along the way.