EERIE light flickers across a solitary face, its fixed gaze concealing a centuries old secret that has confounded experts such as Anwen Caffell for half a decade.

The lips are sealed and it offers clues, nothing more. This is a skull, part of a collection of skeletons unearthed six years ago in Driffield Terrace, York, and no one really knows who they are.

The pressing question on academics’ lips remains: were they, or were they not, gladiators?

“I wish I could say for sure,” says Dr Caffell, “But it’s only when we have finished the recording and looked at the patterns that we will know. And it could be a year away still.”

In the meantime, the skeletons will be on view in York city centre. But not at a museum. York Archaeological Trust has transformed a shop in Coppergate into an exhibition centre which aims to further the gladiator discussion.

And on display will be findings that might one day answer the conundrum, once and for all.

Kurt Hunter-Mann from the trust worked on the Driffield Terrace excavation and says the evidence so far suggests they were gladiators. But archaeology, he says, is a discipline and searching for the answer you want rather than the real one is a recipe for disaster.

“The burial site is unique in Roman Britain, but being unique, we have nothing to compare it with,” he says. “So it’s the usual thing with archaeology; this is the best interpretation that fits the evidence at the moment and with research ongoing, we may still find something conclusive.”

Reticent though Mr Hunter-Mann appears, he admits to a Eureka moment when the most significant piece of evidence was discovered last year.

It is a large bite to the pelvis, probably inflicted by a lion or tiger, according to experts at the National History Museum, and given that you don’t find many prowling along Micklegate, almost certainly sustained during a gladiatorial contest in York.

Nothing like it has ever been identified before on a Roman skeleton.

“Until the discovery we had six theories but this was unusual; it defined an event that took place and took us down the gladiator direction. While nothing is certain, I guess it would stand up in court.”

There are other telltale signs. Hammer and weapon injuries suggest some died in a similarly violent way and most of the skeletons have bigger muscles on their sword arm than on their shield arm, suggesting a lifetime of weapon training.

Then there is circumstantial evidence, such as the mineral testing of tooth enamel which links the men to Roman provinces, including North Africa – a regular source of gladiator recruitment.

And some of the men had been decapitated by sword blows to the neck, a traditional fate for the loser in gladiatorial contests.

With all this data, surely we can say for certain they were buried in the world’s best-preserved gladiator cemetery?

“It would be ideal to have some conclusive pieces,” says Mr Hunter-Mann. “But nothing we have found so far is stopping us going in that direction.”

One of the first theories suggested the bodies were buried after the suppression of aristocratic rebels by Caracalla, another emperor who visited York. This was because of the riches left in the graves for the afterlife.

But that can be explained. Gladiators were held in pop-star-like esteem and, as an excavation in Epheseus, Turkey revealed, similar pomp accompanied the funeral rites for the longest serving among them.

Perhaps the most persuasive argument is again circumstantial. York was a Roman provincial capital and a major military base for troops in the campaign against marauding Scots. Semptimus Severus ruled the empire from York and Constantine appointed himself emperor here in 306AD.

It is inconceivable the dignitaries living in the city would have foregone the gladiatorial spectacles they enjoyed in Rome.

And the combatants had to be buried somewhere.

“Every large settlement had an amphitheatre,” says Mr Hunter-Mann. “And although we have never discovered one in York, it would be an exception if that means there wasn’t one.”

Equally compelling evidence is that York continued to hold major events until the fourth century AD, at a time when many other provinces had gone into decline.

That’s precisely when the last of the men were buried.

The Coppergate exhibition will feature some of the latest findings to support the argument that the men were gladiators. Take skeleton 6DT3, who researchers have named Murmillo, which has a butterfly fracture of the lower arm caused by a blunt instrument. So confident are the researchers they named him after the Murmillo-class gladiator of the early Imperial period.

But still there is a long way to go before any of them will formally declare these skeletonwere from a gladiator cemetery.

“It’s like a jigsaw puzzle, if all the pieces are blue sky, where do you start?” says Mr Hunter-Mann. “But we are building a picture and we know there are more pieces to come. It’s just a question of how many there are and how conclusive they will be.”

Will he ever be able to say with a degree of certainty they were gladiators? “I honestly don’t know, it’s the best theory to go on, and if we get a couple more Eureka moments, it’s possible.”

For now it seems, we’ll have to wait.

There was usually a grisly end

Roman gladiator fights lasted all day, with warriors on horseback opening the show. Then came the Provocatores, or challengers, with only visored helmets and a breastplate for protection. Finally there was the Retiarius armed with just a trident and net to trap his opponents.

No matter how proficient they were, though, most came to a grisly end.

And if a gladiator didn’t get you, there were always the lions.

• Were they Gladiators runs until October 30 at Number 10 Coppergate, York and entry is free to visitors at JORVIK, DIG, Barley Hall, and Micklegate Bar.