The Shroud is a linen cloth approximately 4.42 meters long and 1.13 meters wide, woven in a herringbone pattern. It bears various types of imprints:

• Water stains. They are rhombus-shaped stains symmetrically distributed across the entire cloth. These are halos left by water that soaked the linen during the fire of 1532 and on a previous occasion.
• Burns from the fire in Chambéry. The cloth features two dark parallel longitudinal lines intersected by 22 nearly triangular holes, which until 2002 were covered by patches made, with a clearly different fabric, by the Clarisse Nuns of Chambéry in 1534. The holes are likely due to the falling of a drop of molten metal from the casket in which the Shroud was stored, folded into 48 parts, during the fire that broke out in 1532 in the Sainte-Chapelle of Chambéry, where the Shroud was kept at that time. The heat also caused the fabric to burn, evidenced by the two dark lines. On that occasion, the Clarisse Nuns also sewed the Shroud onto a Dutch linen of the same dimensions to reinforce it. In 2002, as the conservation conditions changed radically, the Dutch linen was replaced, and the patches were removed.
• Ancient burn marks. Alongside both the frontal and dorsal imprints, four series of small L-shaped holes are visible, predating the fire in Chambéry.
• A longitudinal strip. Along the upper edge of the Shroud, a strip of the same fabric as the cloth was sewn in ancient times, missing two rectangular pieces at the extreme edges.
• The double imprint (frontal and dorsal) of a human body, between the two lines of burning. The body appears to have been laid supine on one half of the cloth, with the other half folded over it.
• Bloodstains in various areas (such as the forehead, nape, wrists, feet, and side). These stains, distinct from those elsewhere on the body, are crimson in color and result from a liquid coming into contact with the cloth, leaving a portion of itself on the fabric. They are bloodstains.

The photographic reproduction of the Shroud, carried out for the first time in 1898 by Secondo Pia, revealed that the Shroud image behaves like a natural photographic negative. In other words, the visible image on the Shroud (except for the bloodstains and wound imprints) exhibits a brightness distribution that is exactly opposite to what we perceive in reality. This means that the imprint on the cloth is specular, and therefore, the correct determination of the details appearing to the right or left of the image is read from the photographic negative.

The ability to study a photograph, particularly a negative, which is much clearer and richer in details, marked the beginning of modern scientific studies of the Shroud. Forensic pathologists were the first to highlight the numerous wounds present on the body of the man in the Shroud, a man who was initially savagely beaten, scourged, and then crucified.

It is worth noting that the angles formed by the directions of the blood flows from the same wound indicate that while the blood was flowing, the man assumed two different positions on the cross.

The skin of the trunk and back displays over a hundred excoriated contusions, consisting of rounded and paired figures, approximately two centimeters long, also visible on the lower limbs.

On the right side of the chest stands out a large bloodstain, emanating from an oval-shaped wound approximately 4.5 cm wide and 1.5 cm high, caused by a penetrating and cutting agent that struck at the level of the fifth intercostal space on the right side and penetrated deeply. The characteristics of this wound indicate that it was inflicted after the subject’s death. The blood that flows from it – which continues to drip onto the back at the level of the kidneys, evidently due to the emptying of the chest cavity when the body was laid horizontally – is surrounded by a serous halo dotted with reddish stains, as occurs with blood that has exited a corpse where the serous part has already separated from the corpuscular part.

On the back of the left hand at wrist level, there is a clearly visible bloodstain, formed by two diverging streaks. The blood emanates from an oval-shaped wound, indicative of an injury from a pointed instrument, such as a nail, which has been pulled and penetrated the hand from the inside, exiting from the back.

The feet are more clearly visible in the posterior imprint. The sole of the right foot is fully imprinted, while only the back part of the left foot is visible, near the heel. On the sole of the right foot, the exit hole of the nail is noticeable, from which blood streaks descend towards the toes, indicating bleeding during the crucifixion. Others descend towards the heel, indicating that they emerged at the time of deposition, when the body was in a supine position.

Enrico Simonato: Che cosa è la Sindone, in AA.VV.: Attraverso la Sindone, percorsi storici e scientifici, Claudio Ciabochi Editore, Fabriano (AN),2023.