The first thing that strikes you about one of Ireland's oldest murder victims is his beautifully manicured hands. This man, who once stood an impressive 6ft 6in tall, never did a day's manual labour in his life.
In fact, his fingerprint whorls were so perfectly preserved when his remains came out of the bog near Croghan Hill in Co Meath in May 2003 that gardai were called in to investigate a possible murder.
By the time radiocarbon dating revealed that he had lived well over 2,000 years ago (between 362BC and 175BC), archaeologists had already taken over -- but they still had a murder inquiry on their hands. And a brutal one at that.
Old Croghan Man (as he was christened) met a horrible end. He was stabbed in the chest, his nipples were slashed and a twisted branch of hazel was threaded though a hole cut in his upper arm. He was then beheaded and dumped in a boggy pool on an ancient territorial boundary.
This Iron Age discovery would have been remarkable on its own, but three months before -- and just 25 miles away -- another man's body had been taken from a peat bog on the boundaries of Meath and Westmeath.
Analysis of his remains revealed that he had lived around the same time as Old Croghan Man. "They may well have known each other," says Eamonn Kelly, keeper of antiquities at the Irish National Museum.
In stark contrast, Clonycavan Man, was slight -- possibly as small as 5ft 2in -- but his hair was gelled up in a style akin to a Mohican, adding inches to his height. "Naturally enough, he wanted to make himself look grander," Bog Bodies Project coordinator Isabella Mulhall has speculated. "It's a bit like someone wearing platform shoes."
His elaborate hairstyle showed not only that male grooming has an ancient history, but also that Irish men in the Iron Age sought out imported, luxury products: he used a type of hair gel made of resin from pine trees found only in Spain and France. This man was clearly an aristocrat who was privileged enough to be able to pay a lot of time and attention to his physical appearance.
Yet he too was cut down in the prime of life. He suffered three axe blows to the head -- one which displaced his nose -- a further blow to the chest and he was possibly disembowelled. Like his neighbour Old Croghan Man, he was dumped in a boggy grave on a territorial boundary.
But why did these two important men meet such grisly deaths in the early-centuries BC? A team of 40 international experts set about unravelling the secrets of these two men and, in so doing, have succeeded in opening an exceptional window on Ireland's Celtic past.
Thanks to digital technology, we know what Clonycavan Man might have looked like. Eamonn Kelly says: "When he saw the image, my brother rang and said, 'Ned, he is the image of my wife's cousin in the Midlands'. And it's true, he could be around today -- he looks like a junior Offaly hurler."
Scientists have also been able to piece together these men's final days. Analysis of Old Croghan Man's nails showed that he regularly ate meat, an expensive luxury, but his final meal was of buttermilk and cereal. Could this be a clue to his murder?
Eamonn Kelly thinks so. It is not unusual to find offerings of butter along with quernstones (used to grind cereals) in Irish bogs. He thinks that Old Croghan Man's final meal may provide proof that he was being sacrificed to the goddess of the land.
But this was no ordinary sacrifice. The slicing of both men's nipples may seem grotesque and bizarre in a modern context, but in ancient times the kissing of a king's nipples was seen as a mark of respect, or an act of submission.
"Cutting these men's nipples would have prevented them from ruling as kings in this life -- or the next," Mr Kelly explains. And, he believes, they were very possibly kings, or at least failed candidates for kingship.
But why kill them?
There are several references to the killing of kings in ancient Irish mythology. When a king was inaugurated, he literally married the land. He was expected to ensure a steady supply of crops, corn and milk and to bring prosperity and clement weather. Sometimes kings were killed if they failed to do their duty.
The fact that these Iron Age killings were so brutal also suggests these men were of royal stock. There are early Irish references to the 'triple killing' of kings -- by drowning, fire and stabbing.
"The king," explains Kelly, "was so important that he needed to be killed three times. These men weren't set on fire but their multiple injuries may suggest that these men were being sacrificed to the goddess in all her forms -- the goddess of fertility, the goddess of war and the goddess of sovereignty."
The fact they were found on boundaries is also full of significance. Boundaries have been important since earliest times and, according to Kelly, you often find offerings deposited in them, such as the priceless Bronze Age artefacts that made headlines last year when they were stolen from a pharmacy safe in Stokestown.
In 2009, robbers made off with a gold lunula neckpiece and two gold sun disks, but later threw them in a skip thinking them worthless. They are now in the National Museum and curators have identified the finder of the hoard as the late Hubert Lannon, who dug them up while cutting turf in the bog in 1945. He later gave them to his local pharmacist.
There is one further clue that casts light on the mindset of our Iron Age ancestors. Kelly believes that the hazel branch cut into Old Croghan Man's arm was intended as a sort of semi-magical charm. He thinks it is a spancel or a type of tether that was used to restrain animals.
There are extensive references to these tethers in mythology and how they were used magically on both humans and animals. For example, there are references to a special love charm -- the Burach Bas -- which was made from a strip of human flesh. You placed it on the sleeping person you wanted to bewitch and, according to legend, the person would wake and become your slave.
"In this case," says Kelly, "the spancel could have been used to invoke a protective taboo safeguarding boundaries, and to ward off interlopers."
The picture that has emerged to date is already unparalleled in Irish archaeology. Elsewhere in Europe, the Celts were earning themselves a name as fierce warriors. The Greek historian Stabro wrote that the whole race was "madly fond of war, high-spirited and quick to battle".
Here in Ireland, the country was probably divided into about 150 kingdoms, each one ruled over by a local king. Thanks to the discovery of Old Croghan Man, Clonycavan Man and about five other Iron Age bodies, these people's rites and rituals are also coming into focus.
Human sacrifice was clearly a feature. There have been similar finds in bogs across Europe. In England, the bog body known as Lindow Man was struck twice on the head, garroted and had his throat slit, while Grauballe Man, a body found in a bog in Denmark, was strangled and had his throat cut from ear to ear.
It's easy to think of life at that time as nasty, brutish and short, but, muses Kelly, "people would have had different expectations. We can't really get back into their mindset, but I think it would have been richer in many ways.
"There was very much a sense of community. There would not have been any social isolation and people would have had very defined roles, which would have provided people with a sense of security. Of course, it would have been awful if you got an abscess on your tooth, or an infection.
"As for Old Croghan Man, Clonycavan Man and the other bodies taken from the bog, we have a duty to tell their stories and give added meaning to their lives. These were real people," he says.
Next Wednesday, forensic anthropologist Dr Caroline Wilkinson will explain how scientists reconstructed the face of Clonycavan Man at a free lecture in the National Musuem, Dublin to coincide with Science Week. For other tours and lectures, see www.museum.ie