Scientists at Dundee University were called in to investigate a decapitation which happened 9,000 years ago.
Archaeologists turned to the Centre for Anatomy and Human Identification in Dundee after excavating the skull in eastern Brazil.
The decapitation is the oldest documented in South America by 6,000 years, and raised several questions.
Scientists in Dundee worked out how the decapitation was done with the limited tools available at the time.
Andre Strauss from the Max Planck Institute for Evolutionary Anthropology was excavating the Lapa do Santo site in eastern Brazil when he unearthed a head buried under a rock.
The full skeleton was nowhere to be found, save the disembodied skull and the hands, which were placed over the face in a deliberate pose.
The remains were dated to 9,000 years ago, around 6,000 years before the next oldest known decapitation on the continent, in Peru.
Archaeologists were puzzled to how hunter-gatherers living in a simple society with few tools managed to carry out the gruesome act.
Mr Strauss turned to Professor Sue Black at Dundee University for help.
The team at CAHID were able to compare the case to a modern-day decapitation, and worked out that the skull had essentially been pulled off, with only partial cutting involved.
Prof Black said: "Examining the skull, we saw fractures consistent with hyper extension of the head and rotation.
"There would also have been cutting but the fracturing of the neck bones indicated a violence to the region."
Archaeologists cannot explain why the Lapa de Santo man was decapitated, having ruled out the possibility of his head being a trophy of some kind.
Examination of his bones suggest he was a local rather than an outsider or rival, leading to speculation that his death was part of some form of symbolic ritual.