A team of police detectives and scientists have used the latest criminology techniques to solve what is believed to be the world's oldest cold case - the murder of Otzi the Iceman in the Italian Alps more than 5000 years ago.
Their findings, presented to the International Mummy Congress in Italy, have revealed that the Stone Age warrior was likely killed in a premeditated act of revenge.
A pair of hikers stumbled across Otzi's mummified remains in 1991 and scientists have been painstakingly piecing together the details of his life - and death - ever since.
They have known since 2001 that Otzi was brutally murdered - shot in the shoulder with an arrow from a great distance - but why and by whom was a mystery.
X-rays and a Cat scan revealed a tiny flint arrowhead tip embedded in the mummy's left shoulder. Scientists calculated the arrow would have been fired from about 30m away and probably took him by surprise.
In 2014, the South Tyrol Museum of Archaeology in Italy, where Otzi is kept, commissioned Chief Inspector Alexander Horn of the Munich Criminal Investigation Department to investigate.
Horn was pretty much written a blank cheque in terms of resources and equipment and encouraged to use the latest criminology techniques to crack the case.
Horn and his team interviewed archaeologists who had been working with the Iceman for years as well as experts in forensic medicine, radiology and anthropology. He also examined the site where Otzi was found.
"Otzi probably did not feel threatened shortly before his murder, because the situation at the Tisenjoch location where he was found indicates that he had been resting while enjoying a hearty meal," the museum said in its report to the International Mummy Congress earlier this month.
"In the days prior to the murder he had incurred an injury to his right hand, probably as a result of defensive action during the course of a physical altercation.
"No further injuries could be found, and this might indicate that he had not been defeated in this particular conflict.
"The arrow shot, which was probably fatal, seems to have been launched from a great distance and took the victim by surprise, from which we may infer that it was an act of treachery.
"Further medical findings suggest that the victim fell and that the perpetrator used no further violence.
"The perpetrator probably did not wish to risk a physical altercation, but instead chose a long distance attack to kill the man from the ice.
"As valuable objects such as the copper axe remained at the crime scene, theft can be excluded as the motive."
Horn believes Ötzi's killer acted out of revenge, displaying "a behavioural pattern which is prevalent even today in the bulk of murder crimes".
Scientists also made a startling discovery about the valuable copper axe found among Otzi's possessions.
Until now, it has been presumed that the copper used in the blade was indigenous to the Alpine region and likely sourced from East or North Tyrol.
But research conducted by archaeometallurgy specialist Professor Gilberto Artioli of the University of Padua has discovered that the metal was mined in central Italy.
To determine its origin, Italian scientists took a tiny sample from the blade and compared the proportion of lead isotope - a kind of "finger print" of the ore deposits, which remains unchanged in any objects subsequently made from the ore - with the corresponding data from numerous mineral deposits in Europe and the entire Mediterranean region.
The result pointed unequivocally to South Tuscany.