BOB ABERNETHY: The Shroud of Turin goes on public display in Italy this weekend -- the first time in 20 years. The shroud is an ancient linen cloth with the faint image of a crucified man. Many Christians believe it's the burial cloth of Jesus. In 1988, carbon dating tests put the shroud's origins in the Middle Ages, but scientists have yet to explain how the image appeared on the cloth. And as Mary Alice Williams reports, modern science and faith continue to collide in the search for the truth.
MARY ALICE WILLIAMS: The ancient image is ghostly -- a man crucified, his back scourged. Its enigma is as much as how it got there as what it might be. The Shroud of Turin has survived ancient Turkey, Byzantium, the Knights Templar, flood, and three major fires and has been subjected to every major test known to 20th-century science. One of the scientists was premier microscoper Walter McCrone.
WALTER MCCRONE (Microscoper): Everything that I saw was paint. I can understand why they would like to have it be real, but I'm faced by the fact that my microscope tells me that it is not the real shroud of Christ.
WILLIAMS: But if it's a painting, there are no brush strokes, no artistic method of textile technology or laws of physiology known in medieval times. Most mysterious, the shroud's photographic properties. What is faint to the naked eye leaps out in a developed photo. The shroud itself is in fact a photographic negative. And no technology has yet been able to replicate that.
IAN WILSON (Author and Historian): How do you understand this extraordinary image that you see on the shroud as the work of somebody from that time? To put that scenario forward presupposes that someone back in the Middle Ages understood photography.
WILLIAMS: Historian and author Ian Wilson has just written THE BLOOD AND THE SHROUD, and even radiocarbon dating, which placed its origins squarely in the 13th century, has not shaken his conviction.
Mr. WILSON: What the carbon dating scientists were doing, quite unwittingly, was dating both the original linen from the shroud and also a microbiological accumulation that had grown up through the centuries.
Mr. MCCRONE: It's ridiculous. The amount of material that would have to be on the shroud to change the carbon date from 1st century to 14th century is double the weight of the shroud itself.