Experts have claimed the Shroud of Turin is stained with the blood of a torture victim, supporting claims it was used to bury Jesus.
They say the linen cloth, believed to have been used to wrap Christ's body after crucifixion, contains "nanoparticles" which are not typical of the blood of a healthy person.
The alleged findings contradict claims the face of Jesus was painted on by forgers in medieval times.
Elvio Carlino, a researcher at the Institute of Crystallography in Bari, Italy, says the tiny particles reveal "great suffering" of a victim "wrapped up in the funeral cloth".
These particles had a "peculiar structure, size and distribution", added University of Padua professor Giulio Fanti.
He says the blood contained high levels of substances called creatinine and ferritin, found in patients who suffer forceful traumas like torture.
Professor Fanti said: "Hence, the presence of these biological nanoparticles found during our experiments point to a violent death for the man wrapped in the Turin Shroud."
The Shroud of Turin measures around three metres by one metre and contains a faintly stained image of a man which Christians believe depicts Jesus.
It has been subject to intense scientific study to ascertain its authenticity.
The new findings were published in the US scientific journal, PlosOne, in an article titled Atomic resolution studies detect new biologic evidences on the Turin Shroud.
The findings contradict claims that the shroud was forged in the Medieval era.
Fanti said the characteristics of these particles "cannot be artifacts made over the centuries on the fabric of the Shroud".
Researchers drew on experimental evidence of atomic resolution studies and recent medical studies on patients who suffered multiple acts of trauma and torture.
Elvio added: "These findings could only be revealed by the methods recently developed in the field of electron microscopy."
He said the research marked the first study of "the nanoscale properties of a pristine fiber taken from the Turin Shroud".
The research was carried out by the Instituo Officia dei Materiali in Trieste and the Institute of Crystallography in Bari, both under Italy's National Research Council, as well as the University of Padua's Department of Industrial Engineering.
The shroud is currently displayed at St John the Baptist Cathedral in Turin. During a visit to the city in 2015, Pope Francis paused in silent prayer before the Shroud.