Riggi passed away in 2008, but he had been involved in the intensive scientific examination of the Shroud of Turin by the STURP group in 1978, and on April 21, 1988 was the man who cut from the Shroud the thin 7 x 1 cm sliver of linen that was used for carbon dating.
Even allowing for errors in the measurements and assumptions about storage conditions, the cloth is unlikely to be as young as 840 years." "A gum/dye/mordant [(for affixing dye)] coating is easy to observe on... No other part of the shroud shows such a coating." "The radiocarbon sample had been dyed. Effects of fires and biofractionation of carbon isotopes on results of radiocarbon dating of old textiles: the Shroud of Turin. Actes du III Symposium Scientifique International du CIELT, Nice, France.
Ray Rogers, retired Fellow with the Los Alamos Scientific Laboratory and lead chemist with the original science team STURP (the 1978 Shroud of Turin Research Project, involving approximately 35 scientists directly examining the Shroud for five days), has shown conclusively that the sample cut from The Shroud of Turin in 1988 was taken from an area of the cloth that was re-woven during the middle ages.
Here are some excerpts: "Pyrolysis-mass-spectrometry results from the sample area coupled with microscopic and microchemical observations prove that the radiocarbon sample was not part of the original cloth of the Shroud of Turin.
In 1532, there was a fire in the church in Chambery, France, where the Shroud was being kept.
Part of the metal storage case melted and fell on the cloth, leaving burns, and efforts to extinguish the fire left water stains. In 1534, nuns sewed patches over the fire-damaged areas and attached a full-size support cloth to the back of the Shroud. The Shroud was moved to Turin in 1578, where it remains to this day.