Evidence that dematerialization of the body occurred is the blood stains are intact and not torn, smeared, or broken.
A problem now
arises in connection with the tiny fibrils comprising the threads of the blood-
impregnated cloth, for these are not torn. It is reasonable to suppose that the blood
that was in contact with the cloth dried, thereby causing the body to stick to the
cloth. Three possibilities present themselves: (a) the body rotted, (b) the body was
moved, and (c) the body “disappeared,” perhaps in the manner conjectured by
Jackson and Trenn. The first two possibilities are improbable, however.
If the body rotted then each molecule composing it slowly underwent
chemical change, finally resulting in the body falling away in a manner that would
not tear the thread fibrils. However, the decomposing body would surely have left
some evidence of rot on the cloth lying under the body. Since no rot on the cloth
bearing the dorsal Image exists, the first possibility is rendered implausible. The
second possibility is that the body was removed from the Shroud and perhaps
placed in something else. However, the act of removing the body, some parts of
which would be stuck to the cloth by the dried blood, would tear the blood-
impregnated fibrils. The absence of torn fibrils suggests that the body was not
taken out of the Shroud. It might be objected here that the body might have been
taken out of the Shroud before the blood in contact with the cloth had a chance to
dry. But then it is difficult to understand how the detailed Image of the Man on the
Shroud could have been formed, for, according to this suggestion, the Man would
have been in the Shroud only for only long as it takes blood to dry, probably an
hour at most. This response is admittedly speculative, for no mechanism by which
the Image might have been formed is presently accepted by those most closely
associated with research into the Shroud, but it is difficult to conceive of an Image
forming so quickly that the blood did not have time to dry. The third possibility is
that the body somehow “disappeared,” perhaps by weak dematerialization.
https://www.shroud.com/pdfs/wiebe.pdf
Though not the same dematerialization process as the cloth collapse theory, an example of bodies dematerializing and leaving an image are shadows of Japanese people obliterated by the Hiroshima nuclear bomb.
When the world’s first atomic bomb used in warfare detonated over Hiroshima on the morning of August 6, 1945, a resident was seated on the stone steps outside of the Sumitomo Bank. In their right hand they clutched a walking stick, their left may have been across their chest.But seconds later, they were incinerated in the boiling light of an atomic bomb. In their place was a shadow that served as a horrifying relic of their final moments.
In fact, throughout the center of Hiroshima were a myriad of haunting outlines from window panes, valves, and even people in their last seconds. Etched on buildings and sidewalks now were the nuclear shadows of a city about to be obliterated.
When the atomic bomb “Little Boy” detonated 1,900 feet above the city, a flash of brilliant, boiling light scorched all that it touched. The surface of the bomb burned 10,000 degrees Fahrenheit and anything within 1,600 feet of its blast zone was incinerated in an instant. Anything within a mile radius of its impact site was reduced to rubble.
The heat from the explosion was so intense, in fact, that it also bleached everything in its blast zone, leaving eerie nuclear shadows of human detritus where citizens once were.
https://allthatsinteresting.com/hiroshima-shadows
https://debatingchristianity.com/forum/viewtopic.php?p=1124947#p1124947