How do we know the Poker Holes existed before the 1532 fire?
We are certain that the poker holes existed before the Chambéry fire of 1532. A painting of the Shroud, the Lier Shroud painted in 1516, before the fire, shows the burn holes.
This painting is thought to have been made by Albrecht Durer or Bernard van Orley. We don’t know when the burn holes were caused, but we can be quite certain that it was more than 300 years earlier because they are evident on the Hungarian Pray Manuscript. Other famous copies.
See: Poker Holes and Hungarian Pray Manuscript