It is regarded as one of the coldest cases on record - dating back 33,000 years ago - and has finally been solved.
Forensic analysis by scientists has finally concluded a man who lived in the Upper Palaeolithic period was clubbed to death after he suffered two consecutive blows to his head from a left-handed Stone Age killer.
The fossilised skull of the adult victim, known as the Cioclovina calvaria, is thought to be 33,000 years old and was discovered in a cave in south Transylvania, Romania, in 1941.
The exact cause of a large fracture on the right side of the cranium had long been a source of mystery but researchers based at the Eberhard Karls Universitat in Tubingen, Germany, re-examined the fracture using new technology and found an answer.
The report, published in the respected journal PLOS ONE, stated the injuries could not have occurred through a fall or accidental injury, ''rather they were sustained from multiple blows to the head with a club-like instrument, or from a combination of a fall and a blow to the head.
''The lack of any signs of healing associated with these fractures indicates that the Cioclovina individual did not survive these lesions. A depressed fracture of the extent and magnitude of the Cioclovina DF would have caused fatal brain injuries resulting in a quick demise.
''The location of this lesion suggests that it was inflicted by a blow from a likely left-handed perpetrator facing the victim. Forensic evidence suggests that this early modern European suffered a violent death caused intentionally by another human.''
The Upper Paleolithic era is commonly regarded by academics as one of the great transition periods in the world and this study, say the researchers, also shows the human race at the time was capable of extreme violence and murder.
In order to arrive at their conclusions, the scientists created a set of 12 synthetic bone spheres.
These were tested in a series of different scenarios such as falls from various heights or strikes from rocks or bats.
New technology was then used to create 3D scans similar to the CAT scanners used in hospitals to create detailed images of the insides of bodies.
It was discovered that the man had suffered two injuries at or near the time of death — a straight line fracture at the base of the skull followed by a fracture on the right side of the cranium.
The study stated the results showed that the fracture patterns observed on this skull could not have come after death nor were they accidental - Cioclovina calvaria died as a result of blunt force trauma.