The exact history of Turin shroud, which has gone on display for the first time in 10 years, is hotly disputed. So what do we know about its authenticity?
It's perhaps the most controversial religious artefact in the world. The Shroud of Turin cloth that supposedly wrapped Jesus's body after the crucifixion and became imprinted with his image, has intrigued millions of believers and sceptics alike. Having gone on public display for the first time in a decade, the debate over its authenticity is set to resume.
Numerous historical references to Christ's shroud exist but the only reliable records for the one today housed in Turin Cathedral begin in the 16th Century. The herringbone woven cloth measuring 1.21m by 4.42m (4ftx14ft), is stained with human blood and appears to show the imprint of a crucified man. The most iconic aspect - the apparent image of Jesus's bearded face - is not easily distinguishable to the naked eye, and was only noticed at the end of the 19th Century in an amateur photograph.
But in 1988 the subject seemed to be closed. Carbon dating experts from universities in Oxford, Zurich and Arizona "proved" that the shroud originated in the 14th Century and thus could not be an imprint of Jesus.
And yet many now argue that process was flawed.
Ian Wilson, a historian who has written a number of books on the subject, believes the shroud could indeed be genuine.
"Through no fault of the labs the 1988 sample was taken from the most inadvisable place - the top left hand corner," he says. "Before 1840 the normal process of display was to have the cloth loose and held up by at least three bishops so the corners would have been contaminated."
Another doubt raised was that the sample may have been repaired with cotton strands. "A further problem was that the shroud was in a serious fire in 1532 and smoke introduces a lot of contaminants. All of these factors are ways that the carbon dating could have been skewed as it's not infallible," he argues.
Holes in wrists
Mr Wilson believes the type of weave used is more consistent with ancient than medieval times and that the medical evidence is compelling.
"It's true that thousands of people were crucified at the time of Jesus. But one singular thing about the crucifixion of Christ is the crown of thorns and on the shroud there are a whole series of puncture wounds where the scalp has bled."
Big draw: Queuing to visit Turin shroud exhibition
And whereas every artist imagined Jesus crucified through the palms, the shroud indicates it was through the wrist, which is the only plausible way the body would have remained on the cross, he says.
But how to explain the photographic negative like print of Jesus's face?
"It is something very peculiar. The shroud is some kind of negative of the body it's wrapped up. So you can ask 'Was that the moment of resurrection?' That has to be speculation."
The Catholic church has always refused to take a position on the shroud's authenticity but it expects between 1.5 and two million people to visit and the Pope is due to attend on 2 May. Before it went on display, the Archbishop of Turin, Cardinal Severino Poletto, who is responsible for the shroud, signalled the symbolic importance it attaches to the object: "The Holy Shroud Exhibition is a spiritual and religious event, it is neither touristic nor commercial."
For his part Bruno Barberis, director of the International Centre of Sindonology in Turin, which is dedicated to the study of the Shroud, suspects the cloth is genuine.
"A lot of studies have proved that it's human blood for example - so it's not just done by a painter," he says. "It really is an image left by a real corpse. I think the probability is very high that it's genuine."
Map of cloth
The centre plans to produce "an accurate map of the cloth" to discern whether it was made from the same cloth or contains repairs. Once that has been completed the carbon dating will be repeated, he says.
HOW CARBON DATING WORKS
Small samples taken from object and cleaned of contaminants
Material is then burnt to produce carbon dioxide
CO2 is converted into pure carbon, which is put through machine that measures trace amounts of carbon-14, an unstable isotope
All living organisms contain carbon-14 and when they die the isotope begins to deteriorate at given rate
This gives raw radiocarbon age which can be translated into a calendar age
Entire process takes at least two weeks
Image shows phials and silver foil packet containing sample of the Turin Shroud for radiocarbon dating
Scientists take a different view though. Prof Gordon Cook, at the Scottish Universities Environmental Research Centre, rejects the idea that the sample may have been irrevocably damaged by human hands.
"Pre-treatment methods should get rid of the contamination," says Dr Cook, a professor of environmental geochemistry and a carbon dating expert. "The measurements were done by three really good radiocarbon labs so I've no doubt what they measured is the correct age."
The only question relates to whether the sample contained repairs rather than original material, he says.
Most of the scientists at the 1988 test have either died or retired. But one key witness remains - Dr Hans Arno Synal, who remembers the excitement well. At the time, a 30 year-old PhD student at the Swiss Federal Institute of Technology in Zurich, he now heads up the university's ion beam physics laboratory, and believes that the mystery was solved back then.
"We applied very rigid procedures. If you'd had human contamination then you would have seen a difference between the different degrees of cleaning we did."
But there was no difference, he says. On the question of cotton repairs, he is sure that the textile experts would have picked up any discrepancy in material.
"I don't doubt that the sample has the same structure as the rest of the shroud. So much effort was put into the sample taking procedure."
In short, he is convinced that the object dates from the 14th Century. And yet that doesn't take away from the shroud's power to move people, he adds.
"This is something very special, a historical object whether it originated 2000 or 700 years ago. So I have no bad feelings about people going to see it. Maybe I'll go too. Why not? It's a very historical thing."
He has his own view about why some people are unwilling to accept the science. "It's clear the fibre can't be from Jesus's time. But the debate has not been stopped and maybe it never will. It goes beyond the science. There'll always be some who believe it's true."
Interestingly, it is not the Catholic church that insists the shroud is genuine but people outside it, he says. "Maybe some people want to have proof for the existence of God. But I don't think that's what this is about."
Add your comments on this story, using the form below.
To those who choose to believe, no proof is needed. To those who demand proof, none can be 100%.
Noreen Lundeen, Manchester New Jersey USA
Next is the Santa costume found hanging in a house in Norway - the real clothing worn by Father Christmas? The Turin shroud provides an interesting, Dan Brown style, diversion. But come on, it isn't going to prove anything to unbelievers like me, even if it passes a DNA fingerprint test.
Julian Hitchcock, Cambridge, UK
Your article omits several important facts. The type of fabric and the weave is consistent with 1st Century techniques. No scientific explanation exists for the "image" imprinted in the material, at least no one was able to duplicate it despite the multiple theories that try (unsuccessfully I might add) to explain it. So I think you should present ALL the relevant facts.
Voicu, Los Angeles
I think that the test must be done again, using samples from reasonably central areas of the cloth; then later tests can look further into what makes the imprint. Church objections to damaging a thread or two from the main areas can be answered by the major significance of the answer. If it is really an early photographic image by, and of, Leonardo da Vinci, that would be quite important; but if it could be an image of Jesus, either after crucifixion or at resurrection (perhaps much later), that could help Christians and others to feel His full humanity.
Howard Phillips, London, UK
It is amazing indeed. Other than carbon dating, all other findings such as anatomical mapping in the shroud, its radiation impression, blood strain and location are exact as described in Gospel. Science is truth, but method of finding the truth is in probability and may not be 100 percent accurate. A simple error of .01% could make the carbon dating test result significantly different. In other word God is also truth and Spirit, something He left this mystery to believe by faith only. Motive for making a fake image in linen cloths which is not visible with necked eyes in fourteenth century is also not believable.
Julian Malakar, Jersey City, New Jersey, USA
It matters not in the least if this object is genuine or not, definite proof one way or the other will not change peoples minds. The so called 'faithful' will swear it's genuine even if absolute proof to the contrary were presented to them. People want to believe in this item, and that's enough for them. Sense, science, logic or rational argument is pointless to the superstitious. And in any case even if it were a relic of the correct time period and a genuine impression of a man, that does not prove the identity of that person. As far as I know it's not signed 'J Christ'.
If it is proven to be from the fourteenth century I want to know how the effect was produced. how could someone 700 years ago stump modern scientists?
I totally agree with Dr. Hans Arno Synal. But it'll be a miracle if I even get to see it.
Bert Vaughan, Veliko Tarnovo, Bulgaria
Has any thought been given to getting DNA samples of the blood to do genetic tests the bloodline for authenticity to a particular nationality? If one can trace all humans back in the Out of Africa series surely this can be done here.
Mary , Melbourne, Victoria, Australia