The temperature in the refrigerated display case housing the Bronze Age hunter was gradually lowered for 12 hours. Then, at 8 a.m., the Iceman was wheeled into a sterile laboratory at the South Tyrol Museum of Archaeology in Bolzano.
For four hours, scientists garbed in operating scrubs scraped off bone enamel, chipped away bone and snaked an endoscope into his intestines, harvesting samples for study at half a dozen research institutions and universities.
A forensic expert from the University of Glasgow will try to determine how the ancient hunter died by looking at bone and blood samples that could reveal whether he died a natural death or by accident.
In Zurich, scientists will analyze lead and strontium deposits on his teeth "chemical footprints'' that can reveal more about his environment.
"We have no solutions, but plenty of questions," Peter Vanezis, a forensic medicine specialist, said at a news conference after the Iceman was returned to his chilled case.
DNA tests will feature large in the new round of research into the ancient man.
Scientists in Italy and Britain will examine both the Iceman's DNA and that of the microbes in his intestinal tract. The microbes could be a clue to what sort of food he ate, Italian anthropologist Franco Rollo said.
He said the DNA tests will also look at the mitochondria genome (mtDNA), which could reveal a common ancestry or genealogical continuity between inhabitants of the Alpine regions of 10,000 years ago and those of today.
Previous tests on minute amounts of DNA from the Iceman's lungs suggested he suffered from a lung fungus that could have hastened his death.
Scientists will also try to learn if the crudely carved tattoos found on the Iceman's ankles, knees and calves, were an ancient form of acupuncture, or were added after his death for some unknown reason.
Results of some of the tests carried out on the samples taken Monday should be ready in about six months, said research coordinator Eduard Egarter Vigl.
The Iceman was found frozen in a glacier in the Tyrollean Alps on the Italian-Austrian border in 1991 by two German mountaineers and promptly became the center of an international tug-of-war.
He was first claimed by Austria and taken to Innsbruck. After a survey showed the discovery site was actually on the Italian side of the unmarked border, he was handed over to Italy.
The transfer date was kept secret following threats from Austrian nationalists who have never recognized Italy's annexation of the South Tyrol after World War I.
Since then, the superbly preserved corpse has been kept in a refrigerated viewing chamber at a museum built to house him and the array of weapons and tools found alongsie him, including a copper ax, bow and flint-stone tipped arrows.
His chamber is kept at 21 degrees with a humidity level of 96-98 percent. Museum officials say he will go back on display Tuesday.
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