An expert who felt betrayed by his Whitehall masters

It is the most delicate and difficult question of all for Lord Hutton. What drove David Kelly to take his own life? Was it despair at his exposure as the BBC's source or, as some believe, shame at his own complicity in the controversy?

Some aspects of Dr Kelly's death are beyond argument. Lord Hutton's inquiry had a secondary role as an inquest and there was no evidence to contradict the view that the weapons scientist killed himself. He died on 17 July, from a single cut to his left wrist, in a field on Harrowdown Hill near his home in Oxfordshire after taking an overdose of Coproxamol painkillers.

Why he did so is less easy to decide. There is evidence that Dr Kelly misled senior officials at the MoD about his meetings with journalists and, in particular, what he said to them. Similar doubts emerge about his evidence to the Foreign Affairs select committee. Even close colleagues appear not to have been told the full story.

But then there is what the Government did to him. His wife, Janice, is convinced like Dr Kelly's friends that he was deeply affected by his treatment by the MoD and No 10. She told the inquiry he felt "totally let down and betrayed" when his name was leaked to the press. He told colleagues of "dark actors" working against him.

Dr Kelly already felt belittled and misused by the MoD. After 20 years as one of the world's top biological weapons experts, leading investigations into Iraqi and Russian weapons secrets for the government, the United Nations and MI6, he was reduced to giving speeches and writing policy.

To be called "middle-ranking" by spin-doctors was the last straw. He felt the MoD was unsupportive during his ordeal, threatening his pension and hinting at disciplinary action. He may also have feared losing his coveted role as leader of the British inspection team then being sent back to Iraq. Having been thrown out by Saddam Hussein in 1998 he had longed to return. That chance looked like vanishing, along with his reputation and career.

Yet Dr Kelly had kept a great deal from his wife, apparently unwilling or unable to unburden himself and seek her advice. She had seen hints of his distress before, but he did not admit his role in the controversy until 8 July - 41 days after Gilligan's broadcast, and nine days before he died.

A picture emerges of a very private, reserved and dignified man who, close to the end of his career, was trapped in an intense power battle between No 10, Whitehall and the BBC. But he was also a man who had faced down Soviet and Iraqi heavies, and interrogated countless hostile witnesses. Lord Hutton must decide whether it was intense professional pride or distress at his own fallibility, or a mixture of both, which led him to suicide.

The Oxfordshire coroner, Nicholas Gardiner, has said he may yet hold a full inquest. For the Kelly family, the ordeal may not be over.