In the analysis, the two researchers conducted seven different bloodstain tests on different body parts depicted on the fabric: the hand, forearm, chest, and lower back, along with a belt of blood (whether it is actually blood or paint pigments is another disputed forensic question) at the waist. By pumping blood onto a model at wound points depicted on the shroud, they could compare the angle that gravity pulled the liquid against the direction seen on the linen.

They discovered the angle at which gravity would pull blood dripping from a body in the way seen on the shroud varied with the body part: The forearm rivulets corresponded to an arm held straight out around 90 degrees to the side, for example, while the hand marks matched an arm held out at about 45 degrees. Some hand bloodstains traced angles at odds with each other as well, off by as much as 10 degrees. A simulated spear wound in the chest ran in completely different patterns than the one on the shroud, whether standing or prone. “This is just not what happens to a person on a cross,” Borrini said.