Along a stretch of Port Phillip Bay, one of Melbourne's great archaeological stories is slowly being buried beneath tonnes of sand.

It's a tale that has everything: ghastly crimes, executions, exhumations, grave robbery, publicly-funded Great Depression-era mass-employment construction schemes and, of course, Ned Kelly.

But it's a story that's probably not as well known as it should be. It's not untold, but it's definitely under-told.

John Conder's role in the story is small but fascinating and as good a place as any to start.

Conder — a Yorkshireman who emigrated to Australia in 1859 — was a prolific felon whose crimes graduated in seriousness on each of the half a dozen times he was jailed in Victoria.

John Conder was hanged in 1893 for the murder of of an Indian hawker. ( Supplied: Public Records Office of Victoria )

Larceny. Cattle stealing. Bank robbery. Murder.

In one of the earlier mugshots in his prison file, he is wild-eyed with a thick, bushy beard, but in the final photo taken just weeks before his death, he's old beyond his 54 years. His eyes are desperate and confused.

He's a condemned man.

Conder was convicted of killing Indian hawker Kaiser Singh near Buchan in Gippsland in 1893.

Police found some of the missing salesman's goods in Conder's possession and a jury was not persuaded that scorched bones found after a fire at his property were sheep bones.

Conder was hanged on August 28, 1893 at Old Melbourne Gaol, offering a simple "Lord Jesus have mercy on my soul" before the black cap was drawn over his head and trapdoor was opened.

Enter Ned Kelly

Like dozens of other prisoners executed at the gaol, Conder was buried, unceremoniously, in the prison grounds.

The only record of his, and other prisoners' resting places, was a bluestone wall near the prison graveyard which was engraved with their initials and dates of execution.

If it wasn't for Ned Kelly, they may not even have had that.

The graves at the Old Melbourne Gaol being unearthed in 1929 when the prison was dismantled. ( Supplied: RMIT )

Other gaols in Victoria also buried executed prisoners within the prison grounds, but Old Melbourne Gaol is the only one where an attempt appears to have been made to mark at least some of the graves, and there's strong evidence that the practice started because of Kelly.

No evidence has been found of any grave markers that pre-date Kelly's which, given he was the most famous man in the colony at the time of his death, seems unlikely to be a coincidence.

It was a strangely informal method of recording the final resting places of some of Victoria's most infamous villains.

It was also inconsistent: only around 30 prisoners appear to have had their graves marked in this way.

When the prison was closed in the 1920s, the graves were unearthed and the bodies reburied at Pentridge Prison.

Ned Kelly's fame likely prompted the gaol's practice of using cobblestones to mark condemned prisoners' graves. ( National Archives of Australia )

It was then that the unofficial grave markers proved their worth, allowing authorities to identify who most likely occupied the coffins they were digging up.

Newspaper reports from 1929 recount the moment Ned Kelly's grave was unearthed, prompting "a morbid desecration" by a group of boys who'd gathered to watch.

One of the young "souvenir hunters" was seen leaving the excavation site with a "portion of a skull in his pocket".

It would be decades until Kelly's remains were once again identified.

Tombstones find a new home with a view

Conder's grave was identified by his marker and his name was written on the top of his coffin in builder's lead pencil by some unknown person before his remains were transferred to Pentridge Prison in 1929.

His name was still visible when the coffin was dug up again in 2009 by archaeologists.

His body was buried again — for the third time — two years later.

Only about 30 prisoners at the Old Melbourne Gaol had their graves marked. ( Supplied: State Library of Victoria )

Meanwhile, at Brighton in Melbourne's south-east, a project was getting underway to build a seawall.

It was a massive scheme, designed partly to save the local beach from erosion, and partly to provide employment for the many young men left jobless by the Great Depression.

One thing the project desperately needed was bluestone — and lots of it.

Luckily, there was a healthy supply readily available at the now-unused Old Melbourne Gaol.

The bluestone walls that had stood for nearly a century came down, and the blocks were carted down to Brighton to be used in the seawall, including those carefully chiselled grave markers.

To this day, that's where many of the grave markers remain — slotted neatly into a wall stretching several kilometres along prime beachfront, either facing a daily battering by waves and weather or buried under encroaching sand.

The grave markers were virtually undamaged as they were placed in the seawall by work crews — something principal archaeologist at Heritage Victoria, Jeremy Smith, believes is evidence of at least some kind of attempt at preservation.

The initials 'JVP' are engraved into a stone for Joseph Victor Pfeffer, who was hanged for murdering his sister-in-law. ( Supplied: Heritage Victoria )

"They weren't defaced and they weren't presented upside down or anything," he said.

"I do think at the work crew level someone is trying to preserve some level of identity and it does suggest to me it was known what they were."

At least six of the markers are visible — at least they were — embedded in one 25-metre stretch of the wall on the beach foreshore at Brighton.

The sand moves in

It's a literal rogues' gallery of some of Victoria's worst offenders.

Among them are the grave markers of William Colston, executed for the double-murder of a couple at Narbethong in 1891, Joseph Pfeffer, hanged in 1912 for the murder of his sister-in-law at Albert Park and Fatta Chand who, on the eve of his execution for murder, asked that his parents be told he died of cholera and not at the end of a rope.

John Conder is in this section too. His marker is partly obscured by another section of the wall, but identifiable by the date of his execution inscribed on the block.

The small, square-shaped cobblestone (right) is believed to be the grave marker of John Conder. ( Supplied: Heritage Victoria )

Heritage Victoria documented the grave markers in this section of the wall in 2009 when it was fully exposed. But it's now almost entirely covered by sand.

The bluestone wall is gradually sinking beneath the sand and seawater. ( Supplied: Heritage Victoria )

To the north, just metres from Brighton's iconic bathing boxes and buried beneath half a metre of sand, lies the grave marker of the notorious Martha Needle — one of only two women executed at the Old Melbourne Gaol.

Needle was convicted of murdering her husband by poisoning him with arsenic.

The bodies of her three children were later exhumed and all found to contain arsenic.

She was hanged in 1894.

It's fair to assume that, without Ned Kelly, these markers wouldn't exist.

It's further evidence of the bushranger's extraordinary impact on Victoria's criminal and cultural history.

Seawall may still be hiding a 'wonderful relic' of Victorian history

The challenge facing anyone who wants to see the markers — grim as they might be — is that most of them are now buried under metres of sand.

For archaeologists like Jeremy Smith, this is not a significant problem. In fact, he says it probably affords the markers some extra protection from the elements.

This Brighton seawall contains markers from the graves of prisoners executed at the gaol in the 1800s. ( ABC News: Tim Callanan )

"It's not a concern at all for the time being that they're buried," he said.

"Our preference is for things to be left alone."

But he concedes he would like to see greater recognition of the gravestones for their historical significance and potential cultural value.

"I always try to avoid making moral judgements but these people are significant to the state's criminal history," he said.

"In this Underbelly generation, people just love those criminal stories."

The wall may also be hiding one of Victoria's lost historical treasures: Ned Kelly's original grave marker.

Photos were taken of the marker — bearing the initials E.K. and an arrow — when his grave was unearthed in 1929, but nobody knows what became of it after the prison wall was demolished.

"It could be the threshold for a cottage," posits Jeremy Smith, "or it could be in a shed or it may have ended up in the [sea] wall, concealed in some way."

"It would be a wonderful relic of Victorian history if it were to be found."

For now, that's one part of the story yet to be uncovered.