Scientists previously thought that Oetzi, as the mummy was affectionately nicknamed, died of exposure. Now, they've concluded that he died shortly after being shot with a flint-tipped arrow.

"He only lived for a short time after the arrow impact," said Andreas Nerlich, who headed a joint study by the Ludwig Maximilians University of Munich and experts from Bolzano, Italy.

Shortly before he was shot in the back, the Iceman suffered a non-lethal blow with a blunt object, possibly a stone from a slingshot, Nerlich's team said in a letter to the online journal Intensive Care Medicine.

Explaining the death 5,000 years ago of the hunter has challenged some of the world's best scientists.

Precise timeline established

The team around Nerlich studied chemical changes in living tissue to establish how long each of Oetzi's injuries happened before his death in the snow of the Oetztal glacier in Italy's South Tyrol region.

They said their findings, using new immunohistochemical techniques, of a fatal shot in the back supported the hypothesis that Oetzi was being chased at the time he was killed. The lesion from the blow was just below the arrow strike.

"We're now able to provide information about the age and sequence of wounds," said Nerlich in Munich.

A deep cut in the Iceman's hand, which has already been studied in the past, happened several days earlier, possibly in an accident with his flint knife.

"In the space of a few days he had two injury sequences, which could possibly indicate two separate attacks on him," Nerlich said.

Other scientists estimate Oetzi, who is now on display in the South Tyrol Archaeology Museum in Bolzano, died at age 46. His clothing and weapons offer a window into Stone Age lifestyles.