New studies based on X-Ray photographs of the Turin Shroud (TS) from 1978 and new quantitative tests induced the author to reexamine the viability of a hypothesis he had discussed in a prior work  where he stated that “A possible explanation for the presence of blood and pigments in the samples studied is that the bloodstains were originally produced by human blood which faded with time … (and) have been reinforced by artists in the past centuries.” In fact, the new quantitative results exclude red ochre/iron oxide and vermillion/mercuric sulfide as being responsible for the redness of the stains of blood that are visible with the naked eye on the TS. Having ascertained this result, two problems now arise. First, the origin of the additional reddish material found in correspondence with the TS bloodstains needs an explanation. A hypothesis to be confirmed is that the over 50 documented painted copies of the Relic made in past centuries may have deposited some pigment when they were pressed onto the TS, to be sanctified into higher order relics. The second problem concerns the explanation of the continued redness of the TS bloodstains. In addition to the hypothesis regarding the effects of ultraviolet rays on the high bilirubin content in the bloodstains on the TS and of the presence of carboxyhemoglobin, the author considers the redness of blood coming from an alleged Eucharistic Miracle.
 Giulio Fanti, Giuseppe Zagotto, Blood reinforced by pigments in the reddish stains of the Turin Shroud, Journal of Cultural Heritage, Volume 25, 2017, Pages 113-120, https://doi.org/10.1016/j.culher.2016.12.012
 Heller John H., Alan D. Adler, Peter M. Rinaldi and William Meacham, On the Turin Shroud, Current Anthropology, 24: 4 (1983) 537-538
 Casabianca Tristan, The Shroud of Turin: A Historiographical Approach, The Heythrop Journal 54:3 (2013) 414-423
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