The team also sequenced the human mitochondrial DNA (DNA passed from mother to child) found in dust from the shroud.
The genetic lineage, or haplotype, of the DNA snippets suggested that people ranging from North African Berbers to East Africans to inhabitants of China touched the garment.
"Basically the Shroud of Turin has some strange properties and characteristics that they say cannot be reproduced by human hands," he told CNN by phone from Italy, where he is a professor of organic chemistry at the University of Pavia.
"For example, the image is superficial and has no pigment, it looks so lifelike and so on, and therefore they say it cannot have been done by an artist." His research shows the pigment may simply have worn off the cloth over the centuries since it was first "discovered" in 1355, but impurities in the pigment etched an image into the fibers of the cloth, leaving behind the ghostly picture that remains today. The artist took this sheet and put it over one of his assistants," he said.
For instance, geologists can now determine the origin of rock with incredible precision, by analyzing its ratio of isotopes of certain elements.
The new study suffers from the same issues that made past studies of pollen on the shroud unreliable, said Renée Enevold, a geoscientist at the Moesgaard Museum in Denmark who has analyzed ancient pollen in the past.
"The plant DNA could be from many sources, and there is no way of finding the right source," Enevold told Live Science in an email.
Given that the cloth was publicly displayed for centuries, it's not surprising that so many people touched it, Farey added.
"Apart from ruling out the United States of America as the source for the shroud, it leaves just about everything else open," Farey said.