Forensic pathologists at the University of Leicester in England think they now know how 15th century British monarch King Richard III died --- and it wasn't pleasant.

King Richard died on a battlefield, in August, 1485, – the last English monarch to die in battle -- but for years, no one knew precisely how the despised king met his end.

For years, the mystery remained unsolved because no one knew where his remains were buried. That changed when the king's coffin was discovered in 2012, buried under a parking lot in the English city of Leicester.

Last fall, experts examining his bones reported that they found multiple wound sites on the king, suggesting he had likely been attacked by numerous assailants.

Now, researchers think they know which of those wounds marks the fatal blow.

Pathologist Guy Rutty examined the king's skull and marks on his vertebra, and noted two sharp force trauma wounds at the base of the skull. 

Rutty and his team surmised that those wounds were probably inflicted either by a sword or a halberd, a medieval warfare weapon used to pull warriors off their horses and onto the ground. The halberd consisted of an axe blade and hook mounted onto a long shaft, topped with a spike.

Rutty noted during examination that opposite the site of a sharp force trauma at the base of the skull was a small traumatic lesion on the interior surface of the skull. Careful examination showed that the two injuries lined up together and also with an injury to Richard's first cervical vertebra.

Drawing on his 19 years of pathology experience, Rutty concluded that the sword or halberd spike was likely thrust up from the base of Richard's neck and went deep into his head, killing him.

"The combination of all three injuries provided evidence for the direction of the injury and also the depth to which the weapon had penetrated the skull," Rutty said in a statement.

The team examining King Richard's remains have already published results of their research in The Lancet, including their conclusion that Richard's skeleton sustained 11 wounds at or near the time of his death - nine of them to the skull. 

Researchers said the head injuries suggest the king had either removed or lost his helmet as he was pulled off his horse and was set upon by multiple assailants, leading to what they said was likely a painful death.