Two brothers who escaped Alcatraz half a century ago survived the attempt and not only married and had children after embarking on new lives in Brazil - but may still be alive, their nephew claims.

Bank robbers Clarence and John Anglin made it off the prison island in 1962 after digging a tunnel out of their cells with teaspoons and throwing themselves into the treacherous waters of San Francisco Bay in a makeshift dinghy.

The FBI had maintained the brothers drowned while fleeing 'The Rock' in the middle of the night, along with career criminal Frank Morris.

But their nephew Ken Widner, 54, told Daily Mail Online that he is certain his uncles made it to South America - and established family lives there.

Survived? This photo purports to show Clarence (left) and John Anglin (right), two bank robbers who escaped from Alcatraz in 1962, standing on a farm in Brazil in 1975, their nephews claim

Pensioners: Clarence (left top in his Alcatraz mugshot and bottom left in a computer-generated image of him as an elderly man) and John (top right at Alcatraz and bottom right older) would be 84 and 85 years old today

Convinced: Ken Widner, the nephew of the Alacatraz escapees says he believes they were in Brazil

He spoke out after a History Channel documentary which made public a photo given to his family 20 years ago - and recently forensically analyzed.

The family always had a hunch that the daring escape was successful.

Speaking at his home in Gainesville, GA, he said: 'The family had always believed that the brothers had gone to South America. It's hard to say how we knew; but we did.

'It was thought some family members knew before Fred Brizzi [a friend of the brothers who claimed to have met them in Brazil in 1975].

'We always felt our Uncle Robert knew they survived. Then, on his deathbed, he admitted to being in touch with them for the first 25 years after they escaped.'

The secret was disclosed by Robert Anglin shortly before his death in Ruskin, Florida, in October 2010, aged 84.

Ken said he would now love to go to Brazil to track down his uncles Clarence and John, who would now be 84 and 85 respectively.

He thinks they could still be alive as other family members have survived into their nineties.

'I hope they are still alive as I would love to meet them and I would love for my mother to see them one last time,' he said.

Ken believes Brazil would not extradite the brothers to the U.S. because they married and had children in the country, so becoming residents.

He said: 'We believe that they had wives and children.'

So far, no potential relatives in Brazil have reached out to the family.

It is, however, the case that Brazilian law on extradition prevents non-nationals who have Brazilian wives or children from being sent abroad for trial without their consent.

Legend: The bank robbing brothers fled Alcatraz in the middle of the night on June 11, 1962, in a dinghy they made from raincoats

Mystery solved: New evidence suggests that the trio did not drown, but made it out of the sea and could have got to Brazil, which was then a haven for criminals on the run as it didn't have an extradition agreement

Middle man: They say Fred Brizzi, pictured, who grew up with the Anglin brothers, handed over pictures he took of the pair after bumping into them in Rio De Janeiro. He also offered an explanation as to how they escaped

Such a provision allowed a notorious British criminal, 'Great Train Robber' Ronnie Biggs to live openly in Rio de Janiero from 1970 to 2001. He returned to the UK at his own request.

Ken, and his brother David, 48, recently starred in a History Channel documentary about the Alcatraz escape.

The program, which aired last Sunday, has stirred up a lot of interest and they've received many calls, Ken said - but none leading them to their relatives.

The photograph which has brought renewed interest in the case was taken in 1975 by Fred Brizzi, a smuggler who shipped drugs between South America and Central Florida in the Seventies.

'He had quite the history of his own,' Ken said.

He grew up with the Anglin brothers and bumped into them in a bar during a trip to Rio de Janeiro, according to their nephew.

Inside: Alfred Anglin served his time at the Atlanta Federal Penitentiary in Georgia, before being transferred. He was eligible for parole, so had no reason to try to escape, his family says

Underworld: Brizzi smuggled drugs between South America and Central Florida in the 1970s. Investigators have considered the possibility he helped the brothers get across San Francisco Bay

'There's more that's going to come out that I can't comment on. But there's more to this story,' Ken said.

Brizzi gave the photo to the family in 1992, Ken said. It shows two men in sunglasses on farmland, standing next to a mound of earth, alongside a road.

The criminal said he was the only one who knew for certain that John and Clarence had survived and that they wanted their family to know they were alive and well. Brizzi died of lung cancer in 1993.

Ken said: 'It's my personal belief that Brizzi felt it was the right time to share the picture with the family.

'He had to wait until a certain time that would not get the brothers or family in trouble. When the photo was taken, the FBI were still focused on the case and had threatened family who had any knowledge of the escape.'

The family believe that another uncle, who was also in prison, suffered fatal consequences due to knowledge of his brothers' escape.

Alfred Anglin was an accomplice to John and Clarence's 1958 bank robbery in Alabama but unlike his siblings, he never tried to escape.

Alfred served his time in the Atlanta Federal Penitentiary before being transferred to Kilby prison, Alabama for the remainder of his sentence. When he arrived, he was already eligible for parole.

Ken said: 'In November, he was visited by one of my uncles. Alfred told him: 'I've had contact with them [John and Clarence] and I know where they're at.'

'I visited him with my mom and dad after Christmas. We sat at a picnic table and Alfred told them, 'I know where the boys are.'

'On January 11, the prison said Alfred tried to escape and was electrocuted. But ask any prisoner – why would he do that if he knew he was up for parole at the end of the month?'

The family have long questioned the official account of Alfred's death, Ken said. They believe he was beaten because he wouldn't help authorities locate Clarence and John.

The family finally came to an agreement to reveal their photographic evidence in return for the authorities help in having Alfred's body exhumed.

A coroner did not find any significant trauma to the corpse.

Ken said: 'Just because there was no evidence of broken bones, doesn't mean nothing happened.'

Proof: The declassified FBI document addressed to Edgar Hoover from January 20, 1965, which proves he was told Alcatraz escapee Clarence Anglin may be living in Rio - three years after his daring escape

Informed: J Edgar Hoover, the FBI director, received the file suggesting the escapees were in Brazil

In exchange for the exhumation, the Widners allowed DNA to be taken from Alfred's corpse to compare to bones found in San Francisco Bay six months after John and Clarence's escape – and long believed to belong to one of the brothers.

'The offer to exhume Alfred had increased our trust with the FBI,' Ken said. 'It was give and take.'

The bones were not found to be a DNA match – adding credit to the claim the Anglin brothers made it out of the water alive. A DNA sample from Morris' family in 2010 concluded the remains did not belong to him.

The family only recently entrusted Brizzi's photo with a retired Federal Marshal investigator, Art Roderick.

Ken said: 'The family has never really trusted the FBI and when it was finally turned over, 53 years had gone by.

'We feel like we've found the right person we can trust in Art and felt comfortable enough to share it.'

A forensic artist analysed the facial structures of the men in the photograph and compared it to family pictures and prison mugshots of the brothers.

'It showed up 99.9 per cent accurate,' Ken said.

Art Roderick told Daily Mail Online that the forensic artist, a former police officer with years of experience, had found eight different points on each face in the photograph which matched with the Anglins' mugshots, leading to a 'highly likely' conclusion that it was the Alcatraz escapees.

'Without that, I wouldn't be as keen on this as I am now,' Art said. 'It's a lead but I would like some more pieces of evidence.'

Art, who spent his 26-year career with the Marshals in fugitive apprehension, said: 'I'm still holding to my original opinion that, until we have 100 per cent confirmation they survived, that it's most likely the brothers drowned in San Francisco Bay.

'Forensic artists are not like DNA or fingerprints, it's not an exact science, more like handwriting analysis. But the photographic evidence is very compelling.

'It's one of the great mysteries of the 20th century. But it could still all be a nice story which isn't true.'

He said if the brothers had survived the escape, they would probably have died by now due to their hard living and the fact all their brothers of similar age had passed.

Art said that the photograph could be a misdirection to lead the investigation away from the Anglin brothers real whereabouts but that he would travel to Brazil with the Widners after alerting the Federal Marshal service and Interpol to the development.

Family ties: The Anglins' nephews Ken (center), 54, and David Widner (right), 48, say they own a photograph, seen by investigator Art Roderick (left) that proves their relatives were alive in the 1970s

The retired Fed, who is being paid by the History Channel and is also employed as a CNN law enforcement consultant, refused to reveal further details of the Brazil farm where the brothers were supposed to be living or if they had in fact had families because 'there will be a mad rush to that region'.

The former Fed also suggested that if someone went down privately and began asking questions about the case, they would likely be arrested by Brazilian authorities because the Alcatraz escape is now an open Interpol case.

He added: 'We've had to very careful on this.'

Federal Marshals, who have been handling the case since it was handed over from the FBI in 1979, are still to conduct their own testing on the photograph – using the same image and mugshots.

Before recent developments, Art described the Alcatraz escape as 'a case so cold it was frozen'. He said the Marshal service, who are faced with hunting up to 120,000 felons a year, just couldn't justify spending resources and assigning officers.

Ken Widner said he was not paid by The History Channel but took part in the show to bring attention to his uncles' story. He is also contemplating writing a book on his infamous relatives.

Loving son: The family of the escapees provided Christmas cards John would supposedly send his family every year. This one had his prison number and a stamp saying it was sent from Alcatraz

Further evidence: However the pair insist they were sent three more in the years after the escape. This one did not have the prison markings on it

The 54-year-old has reached out to the U.S. Attorney-General for a pardon for his uncles and to the state of Alabama – the latter of which refused.

He added: ‘But instead of asking for a pardon, we now think we should be asking for time served.

‘I think they’ve served the time. My uncles have spent 53 years away from their family. That’s long enough.’

Declassified FBI files uncovered by Daily Mail Online this week also revealed that the bureau was told the Anglin brothers could be hiding out in Brazil in 1965 – ten years before Brizzi took the photograph.

The redacted files revealed U.S. authorities were working on intelligence that at least one of the brothers, Clarence, was living in Rio.

The potential sighting 50 years ago - sent directly to the Bureau's then-director, Edgar J Hoover from the legal attaché - was considered so significant that agents were dispatched to South America to find them.

The U.S. Marshal, who took over the investigation after the FBI closed its case, also supposedly received a sighting of one of the Anglin brothers by a barman in Rio.

The Brazil tip off was just one of a flurry of possible sightings of the notorious pair across the States in the weeks, months and years after their escape that the FBI was forced to follow up, but the trail on every possible lead went cold.