Using forensic techniques, they have studied the various injuries found on the body that is imaged on the shroud. Using the Bible, they compared these images to the wounds described in the account of Jesus's suffering, and crucifixion, and found that they likely matched.
As for 'graven images', what is wrong with looking at a picture or a statue that reminds us of Jesus or his Mother or one of the Saints, if that leads us to a more fruitful life of prayer? Sometimes people need something visual or tactile to focus their prayer; to keep their minds from wandering, which we're all tempted to sometimes while in prayer. The 'graven image' in scriptures is condemned because it took the peoples' focus OFF of God, and His saving graces.
They cannot possibly prove it was Christ, even if it was legitimate which it is not.
"The 'graven image' in scriptures is condemned because it took the peoples' focus OFF of God, and His saving graces."
It's doing the same thing today and why it is still wrong.