So when did Anne Darwin know her husband was alive?

John Darwin's family reunion splintered into an acrimonious dispute yesterday as his wife admitted a photograph of the couple 17 months before he "came back from the dead" was genuine.

As detectives began to interview Mr Darwin, 57, questions were raised as to how long Anne Darwin had been aware that her husband was alive and whether any other family members were kept in the loop. Last night there were reports that she was flying back to Britain.

The couple's sons appeared to disown them, issuing a statement which talked of their "anger and confusion" at the news. Mr Darwin's father, Ronald, 91, spoke of feeling "betrayed".

"In the short space of time following our dad's appearance in London on Saturday, we have gone through a rollercoaster of emotion," said Mark, 31, and Anthony, 29. "From the height of elation at finding him to be alive to the depths of despair at the recent stories of fraud and these latest pictures. And the shock of being thrust into the media spotlight. If the papers' allegations of a confession from our mam are true then we very much feel that we have been the victims in a large scam.

"How could our mam continue to let us believe our dad had died when he was very much alive? We have not spoken to either of our parents since our dad's arrest and at this present time we want no further contact with them."

Matters were confused further last night after reports that Mark had disappeared from his home. His flatmate in West Finchley, north London, was quoted as saying he had left in the middle of the night with his laptop, leaving a notebook with instructions to his girlfriend Felicity Witts on how to get to London City Airport. The notebook, he added, contained "strange notes" and references to Panama.

Mark Darwin, it emerged, left his position at E C Harris, an international property consultants, the day before his father reappeared, having worked his notice. Anthony resigned from his insurance job with Towergate Risk Solutions in Reading in August. The two brothers insisted yesterday that they were as keen as Cleveland Police to find out where their father had been for the past five years.

The family had claimed they were amazed and thrilled when Mr Darwin walked into a central London police station on Saturday, looking tanned and well, and announced: "I think I am a missing person."

They insisted at the time that he had no memory of anything since 2000, two years before he was last seen, preparing his kayak to go out to sea near his home in Seaton Carew, Hartlepool. After an oar, and then the shattered craft washed up, a massive search was launched in vain. An inquest was held 13 months later and the coroner, Malcolm Donnelly, declared Mr Darwin dead and recorded an open verdict.

After his reappearance, detectives had said they simply wanted to allow Mr Darwin and his family time to overcome the shock. But a woman who put the names John, Anne and Panama into the Google search engine, was said to have found an incriminating photograph from a Panamanian website which appeared to show a beaming Mr Darwin looking fit and well next to his "widow", Anne, in July last year. She explained: "I rang police in Cleveland and the man on the other end said, 'You're joking'."

In the early hours of Wednesday morning, officers were banging on the door of Anthony Darwin's Hampshire home. His father was arrested and led away.

Yesterday the sons' claim that they were innocent victims of a scam appeared to be backed up by their mother, who conceded that the photograph dated July 2006, found on the Move to Panama website, was indeed her and her husband and that she was now living a "nightmare".

She said: "My sons will never forgive me. They knew nothing. They thought John was dead. Now they are going to hate me."

Last night Cleveland Police said they would like to speak to the sons because they were both witnesses in the case. Meanwhile, detectives began questioning Mr Darwin on suspicion of fraud.

But with her apparent admission, Mrs Darwin who emigrated to Panama six weeks ago but has spent the past three summers there remains a focal point of the case. She insisted in an interview with newspapers that she had initially believed her husband was dead but he had got in touch "years later".

The 55-year-old could have faced extradition but said she wanted to return to Britain voluntarily rather than be a "fugitive". Mrs Darwin had only 24 hours earlier claimed the whole thing was a "complete mystery to me". "I am amazed as anyone," she said, before adding: "There I was speaking to my husband. It was the day I had always dreamed about but never really believed would happen."

But with the emergence of the photograph, she said: "It looks as if I am going to be left without a husband, a home or a family now." She continued: "Do, I still love John? Yes, I do and it's probably that that's got me into this situation."

Questions will be raised as to whether she genuinely claimed the life insurance payments and any pension payouts from his job as a prison officer in good faith. There was also speculation as to whether the couple were using a false name in Panama. Mario Vilar, who was pictured with them in the photograph, said they had not used the name Darwin.

In yet another twist last night a woman in Panama City, Patricia Centella de Lopez, said she had seen Mr Darwin only months ago. "Last July I met a new neighbour in the building. When I speak with him, he told me he was new in the building. He told me his name was John," said Mrs de Lopez, adding that she had "no doubt" the man she saw was Mr Darwin.

Meanwhile there were suggestions that Mr Darwin could be charged with wasting police time considering the cost of the search by emergency services after his disappearance. The search, which included a Royal Navy training ship HMS Explorer and an RAF Sea King helicopter, at 15,250 per hour, police, the coastguard and the RNLI, cost at least 70,000. The RNLI charity spent 30,00 alone, with six lifeboats manned by volunteer crews.

Det Supt Tony Hutchinson conceded that there had always been doubts over the disappearance at the time. These were said to have been prompted in part by information from Holme House prison, where Mr Darwin was an officer, and concerns about his alleged relationship with inmates serving terms for fraud. The file on Mr Darwin was reopened three months ago, police said. They were said to have been tipped off about cash transfers. There was also a reported sighting of Mr Darwin in Seaton Carew two years ago.

So many questions...

Who knew all along?

The entire family claimed to be amazed when John Darwin appeared at a London police station on Saturday but his wife, Anne, has since conceded that a photograph of the two of them taken 17 months ago was genuine. She insisted she had thought he was dead until he reappeared "years later". Other family members continue to insist they had no knowledge he was alive. His sons, Mark and Anthony, have distanced themselves from their parents, claiming they might be victims of a scam.

Why did John Darwin turn himself in to UK police?

One theory is that he and his wife rowed and separated after starting a new life in Panama and, with all the assets in her name, he decided to turn up as an act of revenge.

Was this a deliberate fraud from the start?

Whether Mr Darwin did suffer an accident but later regained his memory or whether this was a deliberate fraud from the start will remain at the heart of the case. He insisted he suffered from amnesia though police have admitted they had doubts after questions raised over alleged relationships Darwin had with inmates in jail for fraud at the prison where he was an officer.

Where has he been for five years?

Two years ago a former colleague claimed to have seen him near his home in Seaton Carew, near Hartlepool, while the photograph appears to confirm that he has spent time in Panama. There were questions about whether he had gone to America as he had been in contact with women in the US via the internet when he disappeared.

How much money has Anne Darwin received and spent?

Mrs Darwin has admitted that she received life insurance payments but insisted they were taken in good faith. There are also questions as to whether she received pension payments due to her husband's death in service. In total, these are said to be worth hundreds of thousands of pounds though she has refused to say how much she has received or whether she has spent it.