Witness in NatWest 3 case is found dead

The fight by the so-called NatWest Three - accused of a multimillion-pound fraud involving the collapsed US energy giant Enron - against extradition to America was mired in personal tragedy last night after the body of a senior bank executive questioned by US prosecutors about the case was found in a London park. He is thought to have killed himself.

Neil Coulbeck, 53, who told friends he felt he was being "hounded" by the American authorities during their pursuit of his three former colleagues disappeared from his £700,000 home in east London eight days ago. His body was found on Tuesday morning in a secluded wood 15-minutes' walk from his home in Woodford Green.

The banker, who was head of financial markets in North America for NatWest and its eventual owner, the Royal Bank of Scotland (RBS), between 1992 and 2000, worked alongside the three men accused of fraud. David Bermingham, Giles Darby and Gary Mulgrew, who have fought a long campaign against their extradition to America under new "fast track" procedures, will fly to Houston early today from Gatwick Airport under escort by US federal marshals to face charges of fraud.

The Prime Minister yesterday ruled out any renegotiation of the new treaty, which has yet to be ratified by the Americans. But Mr Blair said that he expected the three Britons to be granted conditional bail in America after being told that US prosecutors would not oppose such a move.

RBS last night denied that Mr Coulbeck, a high-flyer who left the bank in 2004, had personally approved the deal at the heart of the charges against the NatWest Three. But sources familiar with the case said it was certain that Mr Coulbeck had detailed knowledge of the transaction, which took place shortly before the collapse of Enron in 2001 and is alleged to have netted the three men a joint profit of £4.2m.

As one of NatWest's senior business managers in the United States, Mr Coulbeck would have been privy to financial information on deals and is likely to have sat on asset evaluation committees with Mr Bermingham. A statement outlining Mr Coulbeck's role in the transaction forms part of the extradition dossier accompanying the NatWest Three to Texas.

Mr Coulbeck, described by friends as "unassuming and shy", was questioned by FBI investigators about the deal involving the three men and Enron's head of finance, Andrew Fastow, who is serving a 10-year prison term for corporate fraud.

Liberty, the civil liberties group, said last night that it had been approached by friends of Mr Coulbeck who had been told by him that he felt he was being "hounded" by the American investigators. It is understood that the banker, who was likely to be one of the witnesses to be called for the eventual trial of the NatWest Three, was one of several high-ranking British executives at the bank who were closely questioned by the American authorities. Mr Bermingham, who said he was "stunned and extremely saddened" by his former colleague's death, said he was aware of one manager who was "very aggressively interviewed by the FBI and was quite traumatised by the entire experience". It was unclear whether he was referring directly to Mr Coulbeck.

In a statement, RBS, which employed Mr Coulbeck as head of group treasury after he returned from America, said: "There is no evidence that Neil was involved in the approval of the transaction under investigation."

Mr Bermingham, who paid tribute his former colleague as a "superstar, a thoroughly decent, honest, professional guy", said it was too early to know whether his death was directly linked to the extradition case.

The NatWest Three, who were based in London as part of a key team involved with corporate debt deals, worked for the same branch of the bank's investment arm - Greenwich NatWest - as Mr Coulbeck. Greenwich NatWest, which was bought by RBS in 2000 along with the rest of the NatWest group, was involved in regular deals with Enron throughout the 1990s and 2000-2001. In one 1995 document, NatWest described its relationship with Enron as "excellent". It was last night unclear whether Mr Coulbeck had been questioned by American prosecutors in relation to separate inquiries about NatWest's entanglement with Enron.

RBS is currently fighting a massive class fraud action arising from the collapse of Enron and last year paid £11m to settle a case brought by the company's bankruptcy administrators. The US indictment against the NatWest Three alleges that they plotted with former Enron executives to syphon off some $20m from an Enron debt vehicle held in the Cayman Islands tax haven in 2000. It says the trio persuaded NatWest to sell its stake in the Enron company for $1m - far less than it was worth - and pocketed the difference, a total of $7.35m. The deal happened at a time when the UK bank was fighting against a hostile takeover bid from Royal Bank of Scotland which was ultimately successful.

Although Mr Coulbeck, the author of two academic works on banking, was no longer employed by RBS at the time of his death, it is unlikely he could have ignored the furore over the NatWest Three ahead of their extradition. Two days before he vanished from his large mock-Tudor detached house, extensive details of NatWest's dealings with Enron and the American criminal investigation were published in British newspapers.

Mr Coulbeck and his wife, Susan, had lived in Woodford Green for six years. Neighbours described him as a quiet, distinguished-looking man whose only eccentricity was to wear a beret. The couple have two adult sons.

As the NatWest Three prepared for their extradition journey yesterday, they said events had put their own problems in perspective. Mr Bermingham said: "One day, when this is all over, I'm going to be coming home to my wife and children and some poor guy is not and my heart goes out to his wife and family."