No book about Dr David Kelly could start anywhere other than at the end.

Kelly is found, dead, in a wood near his Oxfordshire home. A public inquiry, headed by Lord Hutton, concludes that Britain’s leading germ warfare expert has committed suicide. Those who question the procedure or the verdict are scorned as conspiracy theorists. Four years later, in response to a Freedom of Information Act request, the police reveal that there are ‘no fingerprints whatsoever’ on Kelly’s knife, on the tablet packets in his coat pocket or on the water bottle found nearby. This single stark fact — which was simply not mentioned at the public inquiry — seriously undermines the suicide verdict.

There are countless other odd and perplexing aspects to the story. The last person to talk to him commented that Kelly seemed relaxed and normal, had no coat — it was mid-afternoon on a mid-July day in 2003 — and was heading in a direction away from Harrowdown Hill, where he was found, wearing his Barbour jacket, the next morning.

The journalists who had doorstepped Kelly’s house had inexplicably vanished, despite the publicity surrounding his controversial TV grilling by parliament’s Foreign Affairs Select Committee two days earlier.The following day, when searchers found the body, Kelly appeared to be slumped against a tree. Half an hour later, he was flat on his back, several feet from the trunk. The incurious Hutton seemed unconcerned that the body had moved. Kelly supposedly cut his left wrist with a blunt gardening knife, but the ambulance crew — veterans of many suicide attempts — have always said there was too little blood around the body.

In any normal case of sudden and unexplained death, an inquest would be held. Because the 59-year-old Kelly was at the centre of a huge political row about the Labour government’s ‘sexed-up dossier’ and its reasons for going to war in Iraq, Tony Blair was quick to cut across this procedure. Instead, he created the Hutton Inquiry, an inept, inadequate substitute that could not put witnesses on oath, failed to test evidence and left a nasty taste in the mouth.

The novelist Robert Lewis has written the first full biography of Dr David Kelly, CMG, veteran of 37 UN weapons inspection trips to Iraq, chief scientific officer at the MoD and long-time head of biological warfare at the Porton Down laboratory on Salisbury Plain. Until now, we have had only one book on the man. The Strange Death of David Kelly by Norman Baker, Lib Dem MP, came out in 2007 and concentrated on the end of the story. It brought together many troubling details, but was too easily dismissed by those who found its tentative conclusion — that Kelly was probably murdered by an Iraqi hit squad — hard to swallow.

Lewis delivers no such bombshell. After 350 pages, he accepts that it was suicide, though he strongly suggests that Kelly’s relationship with his young American translator may be more relevant than generally recognised. In the MoD canteen, he tells us, there is practically a consensus on the matter. He quotes a top psychologist at Porton: ‘It’s cherchez la femme — they all think it’s to do with Mai Pederson.’

Pederson was bright, vivacious and 20 years younger than Kelly. She was a USAF sergeant, a talented linguist and, according to both her former husbands, a spook. Kelly and Pederson met repeatedly and worked together as Kelly scoured Iraq for traces of Saddam’s elusive WMDs. Pederson denies any sexual involvement, and, as Lewis says, ‘She may very well be telling the truth.’ Kelly’s wife, Janice, knew Mai, and she had even stayed at their house.

But the affection and influence is unmistakable. Pederson was a follower of the Baha’i faith, and Kelly, a lifelong agnostic, converted (neglecting to mention this to Janice for two years). They spent months in each other’s company when Kelly was in New York in 1999, with a three-week interlude together at Mai’s other home in Monterey, California. Lewis is right to say that it looked bad. Even if they never kissed, the appearance of marital disloyalty and security compromise would have made any threat to disclose the relationship a ticking timebomb for Kelly. On top of the other pressures from his employers and from the warring factions in Downing Street’s dogfight with the BBC, it is possible that Kelly was facing officially sanctioned blackmail.

The main body of Lewis’s book is concerned with tracking Kelly’s rise to eminence, first as an academic and then, in a Faustian bargain that brought him status, wealth and power, as a UN weapons inspector, a confrontational interrogator and a semi-detached helper for several countries’ intelligence services. Ultimately, Lewis makes clear, Kelly and the other UNSCOM weapons inspectors became willing political pawns in a deadly US-led game that involved keeping the inspections going to justify continuing UN sanctions against Iraq, in the hope of bringing down Saddam. These sanctions led to illness, starvation and, Lewis estimates, the deaths of well over 100,000 Iraqi children. On his later trips to Baghdad, Kelly would be confronted outside his hotel by Iraqi mothers thrusting dead babies in his face.

The UN’s Humanitarian Coordinator in Iraq, Denis Halliday, resigned in despair, after 30 years with the United Nations, calling the UN Security Council sanctions ‘genocidal’ and criminal. ‘International law has no provision for the disproportionate and murderous consequences of the ongoing UN embargo,’ he said.

Kelly was no fool, no bumbling boffin, though it sometimes suited him to appear like that. The solitary boy from the Pontypridd hillside, whose father left when he was young and whose mother took an overdose while he was at university, had become an internationally respected microbiologist. Lewis cannot forgive him for trading this scientific career for an increasingly duplicitous life dominated by the ruthless plots of spymasters and governments. The author’s anger makes for impassioned, persuasive writing, especially in the later chapters, but this is, inevitably, an incomplete tale.

For years now, there has been a steady, relentless, unhysterical campaign for a full coroner’s inquest to establish the facts of David Kelly’s death. Successive governments have stonewalled. Eventually, though, they will concede. This is the only sudden and suspicious death in modern times that has not been followed by a proper inquest. Our coroners have been serving the truth, and us, well since 1194. When they are allowed to bring their skills to bear on the death of Dr Kelly, there will be room for a much better book than we have seen so far.