Death of a scientist

"Functus officio," he said, in a barely audible whisper, best translated as "my task is done, I have no further function".

However, it would have been difficult three-and-a-half years ago to find anybody at Oxford's Old Assize Court who really believed that Mr Gardiner's words would draw a line under the death of Dr Kelly, the weapons expert found dead near his home in Southmoor.

For the circumstances of Dr Kelly's death, his involvement in the world of weapons inspections and the political impact of the tragedy meant it was always going to be fertile ground for conspiracy theories.

But few could have guessed that the author viewed as the conspiracy theorist-in-chief should be the former Liberal Democrat environment spokesman, Norman Baker MP, who gave up his front-bench job to try to establish "what really happened" on Harrowdon Hill in July 2003.

When invited by Sir Menzies Campbell to shape the Lib Dems' green policies, Mr Baker instead chose to spend two years focusing his mind on how Dr Kelly's body came to be found in a remote Oxfordshire wood.

His book, The Strange Death of David Kelly, published yesterday, argues that Dr Kelly did not kill himself, rather that he was murdered.

Not only that, it concludes that an establishment cover-up set out to make the killing appear to be suicide in the belief that this would be in the national interest.

Make no mistake, the MP for Lewes, who now speaks on constitutional affairs as Shadow Minister for the Cabinet Office and Chancellor of the Duchy of Lancaster, is fully aware of the enormity of what he has done.

"I am not naive as a politician," he told me.

"I am aware it is high risk. It was high risk to give up an important role in the party and it is high risk for anyone to challenge the official verdict of events and be labelled a conspiracy theorist.

"I am sure political opponents will seek to maximise any discomfort.

"There had always been a chance that it led nowhere. But I don't believe identifying risk is a reason for not doing the right thing."

While his party colleagues were listening to The Queen's Speech, in his Westminster Office he offered me some insight into the prolonged debate in his own head.

"There were two immediate considerations: how it would affect my constituency work and the impact it might have on Mrs Kelly and her family. I weighed that very carefully. In fact, I did three months' work before I said anything. I then published an article in the Mail on Sunday to set out my concerns.

"The response was overwhelmingly in favour of me continuing.

"I received hundreds and hundred of letters and emails and phone calls. All of them, except three, were supportive of my decision to publish and willing me on. It was the largest response I had to anything I had done as an MP."

He wrestled with the dilemma over days before consulting parliamentary colleages.

"In the end I concluded that there was an overwhelming public interest to deal with what is unfinished business.

"Here was a good man, who did more to dispel the threat of weapons of mass destruction than anyone else on the planet.

"And here he was with a very ignominious end. At the very least it needed to be investigated properly. If my book causes distress to Mrs Kelly, I apologise for that."

With Mrs Kelly on record as saying very clearly that she believed her husband's death was suicide, he insists: "The last thing I wanted to do was cause the family further grief, which I recognised might come from further media coverage."

The 50-year-old MP made no attempt to contact Mrs Kelly, who still lives in Southmoor, or her daughters after learning from the family solicitor that they did not wish to co-operate.

But he now reveals that two unnamed members of the family agreed to speak to him.

The book seems to have been motivated by the MP's belief that the Hutton Inquiry was a travesty and by a letter sent to the Guardian from medical specialists, who questioned whether Dr Kelly's death could have been suicide.

"I began to take an interest in it myself," said Mr Baker, well known as a campaigner in the field of animal welfare.

"I simply could not believe that suicide is supported by the facts. For me the key question is 'why did he die the way he did?'."

Mr Baker believes that a scientist with Dr Kelly's understanding of the human anatomy would not have attempted suicide by cutting his wrist.

"The artery in question is hidden deep in the wrist and can only be accessed by cutting through nerves and tendons - an extremely painful process."

Choosing a blunt concave pruning knife would have only increased the pain.

The MP writes: "It might be argued that Dr Kelly did not leave his house in Southmoor with the intention of committing suicide - but that a black mood came upon him in the woods and that the decision was spontaneous.

"He then found that the only weapon to hand was this knife and used it as best he could.

"This theory, however simply does not hold water, if we are also to believe that Dr Kelly brought with him from his cottage 30 coproxamol tablets, which according to the official version of events, were used either to dull the pain of the incision or to provide a second parallel method of achieving suicide."

Two paramedics called to the scene spoke of the "remarkably little blood around the body" and the MP also questions why Lord Hutton made no reference to the lack of any fingerprints on the knife.

Then there is the issue of Dr Kelly's state of mind.

"On that last morning he was sending emails saying he was going to Iraq and the worst was over. He actually booked a flight back to Iraq."

But it is the MP's alternative version of events that will cause widespread anger, both from people disinclined to accept the official verdict and those who will view the book with contempt.

Having satisfied himself over two years that it was "nigh-on clinically impossible" for Dr Kelly to have died by his own hand in the manner described, Mr Baker says only one alternative remains - that the weapons inspector was murdered, possibly through an injection "by person, or persons, unknown".

"I think it was an Iraqi group," he told me. "Different sources have told me the Iraqis were involved. There is a high degree of correlation. Sources on the record and anonymous point in the same direction."

Revenge by Saddam Hussein loyalists is put forward as a possible motive.

But he argues the involvement of an Iraqi group with London links, fearful that revelations from Dr Kelly could affect their credibility with the US and the UK Governments, is much more likely.

He discounts one idea that Dr Kelly's talks with a Summertown company about publishing a book could be significant.

The theory becomes more convoluted because Mr Baker goes on to suggest that it was not the killers, but dark forces in the British establishment who made the murder look like suicide.

Mr Baker's scenario can only be summed up with difficulty.

The British Government suspects an Iraqi operation.

It was recognised that the murder of Britain's leading weapons inspector by terrorists at a time when the controversy over the legality of war raged, with public opinion dangerously unpredictable, could leave the Government irretrievably damaged.

Mr Baker said: "If this scenario is correct, it is necessary to conclude that a small number of senior people knew."

Perhaps recognising an ever-growing look of disbelief, he added almost apologetically: "It may seem an odd conclusion, but it is the only one I can find to fit the facts. It may not be 100 per cent right, but it is certainly more credible than Lord Hutton's conclusion."

Some of those who came forward to help the MP, including former members of the intelligence service, faced ominous warnings and threats, he discloses.

"It is unsatisfactory, not being able to give more details. But I have details of names and occupations. I was faced with the position of either not including information that is relevant or putting information in without being able to identify people by name."

His case is perhaps at its strongest when he deals with the unusual process under which Dr Kelly's death was examined, with the Hutton Inquiry effectively carrying out the function of the coroner's court.

"One QC I spoke to believes the entire process to be flawed because it was not a statutory inquest.

"Nobody was obliged to give evidence under oath. There was no proper examination of the police officers. It was less vigorous than if you found someone down there on the pavement."

From the television in his office, we could see that The Queen's Speech was over.

As I walked across Parliament Square, with large crowds still awaiting the departure of the monarch, the thought occurred how much unnecessary pain the MP for Lewes will cause if he is wrong.

Yet if he were even a tenth right, it would be a far more terrible book.