The graves of an English couple murdered in Guatemala in 1978 have been rediscovered after 40 years.
The families of Peta Frampton and Chris Farmer from Manchester had been told their remains had been lost forever.
A letter and two pictures taken in 1984 were the only clues to their location in a cemetery in Puerto Barrios.
But new evidence has led Chris's sister, Penny Farmer, along with 5 Live journalist Dan Maudsley, to discover the couple's final resting place.
In July 1978 the bodies of 25-year-old Chris and Peta, a 24-year-old lawyer, were discovered tied up and attached to engine parts, 200m off the coast of Guatemala.
The couple, from Chorlton in Manchester, had last told their families they were travelling on a boat owned by an American, Silas Duane Boston.
As part of the investigation, the FBI had tried and failed to find the couple's graves in the Puerto Barrios cemetery where they were known to have been buried.
The only person known to have visited the graves was an American pastor, Garry McClure, who took photographs of the cement crosses in 1984. He sent the pictures, and a description of his visit, in a letter to a family friend of the Farmers.
The pastor was retraced for the BBC podcast Paradise and passed on vital new information that gave hope the graves could be found.
Armed with the new clues, Penny and BBC reporter Dan went to Puerto Barrios in December to make one last attempt to find the graves.
The sprawling cemetery was as chaotic as the FBI had described.
"It was far more shambolic than I ever appreciated," said Penny.
"Tomb after tomb. There was no pattern to them."
Remarkably, after an hour of searching, the details the pastor gave them led to Chris's graveside. Moments later, Dan found Peta's cross under a pile of leaves.
"I didn't realise how important it was until I was there standing by his graveside, that was actually quite emotional," said Penny.
As the podcast reveals, finding the graves has now raised even more questions.
"We thought the FBI were working really hard. They told us that there was a concerted effort, but by following the pastor's details to the letter we were able to find them in just an hour."
The prolonged efforts by investigators to find the graves is believed to have delayed the arrest, potentially denying the families the opportunity to see Silas Boston face trial.
The FBI officer who led the investigation, SSA David Sesma, said it was "unfortunate for the Farmer and Frampton families that we were unable to find them".
He defended the agents sent to find the graves, saying they had managed to locate several trial witnesses and "did good work".