At the centre of the controversy is a linen sheet, 4.37 metre long and 1.11 metre wide. Some claim that Jesus was wrapped in this shroud after his crucifixion. The details of the contoured markings on the cloth are still remarkably clear and show the outline of the body of a man who was 1.81 metres tall with a beard and long hair; there are clear signs that he had worn a crown of thorns and that his hands and feet had been injured with nails. Although the Catholic Church has never recognised "Christ's shroud" as a religious relic, it is revered as such by many Christians all over the world.

The history of the Shroud is quickly told. First mention of it was made in a manuscript in 1532, when it was saved from a church fire and subsequently patched up by nuns. Only a pilgrim's commemorative medallion from 1357, picturing King John the Good and the Knight Geoffroy de Charny displaying the Shroud to the French congregation in the Collegiate Church in Lirey near Troyes, is older. Finally, on the 14th September 1578 the Shroud was brought to Turin, where it has remained ever since. Every year, on the 4th of May, a special mass is held in honour of the holy cloth in the Cathedral of Turin–in 1998, what's more, in the presence of the recently deceased Pope John Paul II.

But one question has never been answered conclusively: who was the man whose image the shoud portrays? Is it really the Son of God?

In 1973 Walter C. McCrone and his team of serologists cast doubt on the authenticity of the traces of blood whereas, five years later, forensic scientists declared that the blood stains on the Shroud were from the rare blood group AB and were authentic. It is widely acknowledged today that the sheet had indeed been used to shroud a body.

Still no certainty: Apart from the controversy on the age of cloth another fundamental question remains open: Whose image can be seen on the Shroud? Is it that of Jesus? large

The Shroud of Turin: ETH scientists also examined and carbondated it. Picture: ETH Zurich large

But was it Jesus? In 1989 three teams of researchers, in Arizona, Oxford and Zurich determined the age of the cloth by the means of radiocarbon dating. Results were published in the specialist magazine Nature (2). The team in Zurich around Georges Bonani from the ETH Institute for Particle Physics (3) were given a sample weighing 52.8 milligrams for their examinations. "First of all this sample was divided into two parts. From the first, three smaller samples were prepared that were subsequently cleaned in different ways in order to investigate possible impurities. The second half of the sample was analysed later on," report the scientists from Zurich. "All samples delivered consistent results.“ ETH dated the samples and concluded they were 676 years old; the scientists at the University of Oxford arrived at 750 years and the physicists from the University of Arizona at 646 years. In other words, if the Shroud is at most 750 years old it is impossible that it was used to for Jesus' burial.

First doubts about the dating were raised in 1998 by Avinoam Danin, Professor of Botany from the Hebrew University of Jerusalem. His conclusion: pollen and plant material, which he found in the cloth, pointed to the era of Jesus. His work, however, was never published in a scientific journal. For his pollen research Danin had continued to work along the lines of the criminologist, Max Frei-Sulzer from Zurich (Frei subsequently achieved notoriety for his erroneous assessment of the Hitler Diaries).

Criticism concerning the dating has now gained new support. The analytical chemist Raymond N. Rogers from the Los Alamos National Laboratory in California carried out further analysis on another sample of the cloth (4). However, he did not use the radiocarbon dating method. Roger's examined the vanillin content in the fabric. Aldehyde is produced when the lignin content in the linen decomposes. Vanillin, however, is not stable either: the older the fabric is (and the higher the temperature at which it has been stored), the fewer traces it contains. Using pyrolysis-mass spectrometry the chemist ascertained that there was no vanillin left in the sample and concludes that the fabric must be between 1300 and 3000 years old. This means that it is entirely possible that Jesus was wrapped in this shroud.

But this research is not acknowledged as proof, as the method in question is widely disputed by most textile historians. Shortly before he died on 8th March 2005, Raymond N. Rogers, proposed that the shroud be submitted to radiocarbon dating once again–the next scientific study seems a certainty and the mystery story surrounding the famous Shroud of Turin is ikely to go on.