David Christopher Kelly was born in Llwynypia, Glamorgan, South Wales, on 14 May 1944. His parents were Thomas John Kelly and Margaret, née Williams; Thomas was a schoolteacher who was serving in the Royal Air Force Volunteer Reserve as a signals officer during the Second World War. Thomas and Margaret divorced in 1951 and she took her young son and moved in with her parents in Pontypridd. From the age of eleven he attended the local grammar school. He was a keen sportsman and musician at school, and represented Wales in the youth cross-country running team; he played double bass in the National Youth Orchestra of Wales and played the saxophone to a high standard.

In 1963 Kelly was admitted to the University of Leeds to study chemistry, botany and biophysics. His mother died two years later from an overdose of prescription barbiturates. Although the coroner’s inquest gave an open verdict, Kelly believed she had killed herself. As a result of the death, Kelly suffered from insomnia and was prescribed sleeping pills; he was also given an extra year to complete his degree. Kelly graduated in 1967 with a BSc in bacteriology; he then obtained an MSc in virology from the University of Birmingham. Between his first and second degrees, on 15 July 1967, he married Janice Vawdrey, who was studying at Bingley Teacher Training College.

Kelly joined the Insect Pathology Unit at the University of Oxford in 1968, while a student of Linacre College. In 1971 he received his doctorate in microbiology for his thesis “The Replication of Some Iridescent Viruses in Cell Cultures”. In the early 1970s he undertook postdoctoral research at the University of Warwick, before moving back to Oxford in the mid-1970s to work at the Institute of Virology, where he rose to the position of Chief Scientific Officer. Much of his work was in the field of insect viruses.

In 1984 Kelly joined the Ministry of Defence (MoD), as the head of the Defence Microbiology Division working at Porton Down, Wiltshire. The department had only a small number of microbiologists when he arrived, and most of their work involved the decontamination of Gruinard Island, which had been used for experiments during the Second World War with weaponised anthrax. He increased the scope of his department, obtaining additional funding to undertake research into biodefence. Because of the work undertaken by Kelly and his team, the UK were able to deploy a biodefence capability during the 1990–1991 Gulf War.

In 1989 Vladimir Pasechnik, the senior Soviet biologist and bioweapons developer, defected to the UK and provided intelligence about the clandestine biological warfare (BW) programme, Biopreparat. The programme was in contravention of the 1972 Biological Weapons Convention which banned the production of chemical and biological weapons. Pasechnik was debriefed by the Defence Intelligence Staff (DIS), who requested technical assistance to process the information on chemical and biological matters; Kelly was seconded to the DIS to assist with his colleagues Brian Jones and Christopher Davis. They debriefed Pasechnik over a period of three years.

Kelly undertook several visits to Russia between 1991 and 1994 as the co-lead of a team from the UK and US who inspected civilian biotechnology facilities in Russia. One of the restrictions placed on the inspectors was that visits could only be to non-military installations, so, for the first visit in January 1991, the team visited the Institute of Engineering Immunology, Lyubuchany; the State Research Centre for Applied Microbiology in Obolensk; the Vector State Research Center of Virology and Biotechnology in Koltsovo; and the Institute of Ultrapure Preparations, in what was then called Leningrad (now Saint Petersburg). The team faced obstruction by the Russians, who tried to stop inspection of key areas of the facilities, and who lied about the use to which parts of the installations were put. On one visit to the Vector facility, Kelly had a conversation with a laboratory assistant—one who was too low grade to have been fully briefed by the KGB. Kelly asked the assistant about the work he was doing, and was surprised when the man said he was involved in testing smallpox. Kelly questioned Lev Sandakchiev, the head of Vector, about the use of smallpox, but received no answers. Kelly described the questioning sessions as “a very tense moment”.

Following the end of the Gulf War (August 1990 – February 1991), United Nations Security Council Resolution 687 imposed the articles of Iraq’s surrender. The document stated “that Iraq shall unconditionally accept the destruction, removal, or rendering harmless, under international supervision, of … All chemical and biological weapons”. This was to be made possible by “The forming of a special commission which shall carry out immediate on-site inspection of Iraq’s biological, chemical and missile capabilities, based on Iraq’s declarations and the designation of any additional locations by the special commission itself”. The group set up was the United Nations Special Commission (UNSCOM), and Kelly was appointed to it in 1991 as one of its chief weapons inspectors in Iraq. The Iraqis had provided Rolf Ekéus, the director of UNSCOM, with a list of sites connected with the research and production of Weapons of Mass Destruction (WMD) in the country, about half of which had been bombed during Operation Desert Storm. These sites provided the starting point for the investigations. In August 1991 Kelly led the first group of UN BW investigators into the country. When asked where the inspection teams would visit, he told reporters “We will go to sites which we deem to have characteristics associated with biological activity, but at the moment … I have an open mind.” The first UNSCOM missions finished with no evidence found of an Iraqi biological or chemical programme, although they did establish that some sites suspected by US intelligence services of involvement in biological or chemical warfare research were legitimate. These included a bakery, a pharmaceutical research business in Samarra, a dairy and a slaughterhouse.

In the 1996 Birthday Honours Kelly was appointed as Companion of the Order of St Michael and St George (CMG); the citation reads:

UNSCOM undertook 261 inspection missions to Iraq between May 1991 and December 1998, 74 of which were for biological weapons. Kelly led ten of the missions involved in BW inspections. In 1998 and 1999 Iraq refused to deal with UNSCOM or the inspectors; the country’s President, Saddam Hussein, singled out Kelly by name for expulsion from the country. During an inspection mission to Iraq in 1998, Kelly worked alongside an American translator and US Air Force officer, Mai Pederson, who introduced him to the Baháʼí Faith. Kelly remained a member of the faith for the rest of his life, attending spiritual meetings near his home of Southmoor, Oxfordshire. He was, for a time, the treasurer of his local branch, based in Abingdon, Oxfordshire. His time in Iraq left him with a deep affection for the country, its people and culture, although he abhorred Saddam’s regime.

In 2000 UNSCOM was replaced by the United Nations Monitoring, Verification and Inspection Commission (UNMOVIC), whose mission was similar to that of UNSCOM, and was to:

In a 2002 review of the verification process, Kelly wrote:

In his 2002 State of the Union address, George W. Bush, the President of the United States, discussed the use of WMD by the Iraqi regime and claimed that, along with Iran and North Korea, Iraq was part of an “axis of evil, arming to threaten the peace of the world”. Later that year he declared that “the stated policy of the United States is regime change”. As part of the British government’s arguments for war on Saddam, Tony Blair, the British Prime Minister, published a dossier on Iraqi WMD on 24 September 2002. The dossier, which was “based, in large part, on the work of the Joint Intelligence Committee (JIC)”, included the statement that the Iraqi government had:

On 8 November 2002 the UN Security Council passed Resolution 1441, “a final opportunity to comply with its disarmament obligations under relevant resolutions of the Council; and accordingly decides to set up an enhanced inspection regime with the aim of bringing to full and verified completion the disarmament process”. The resolution stated that the Iraqi government needed to provide full details of its WMD programme within 30 days. As a result of the increasing pressure on the Iraqi government, UNSCOM inspectors were readmitted to the country and information was provided on the Iraqi WMD programme. According to Kelly, despite the steps taken, Saddam “refuse[d] to acknowledge the extent of his chemical and biological weapons and associated military and industrial support organisations”, and there was still a concern about “8,500 litres of anthrax VX, 2,160 kilograms of bacterial growth media, 360 tonnes of bulk chemical warfare agent, 6,500 chemical bombs and 30,000 munitions capable of delivering chemical and biological warfare agents [which] remained unaccounted for from activities up to 1991”.

Kelly was questioned by the Liberal Democrat MP David Chidgey about conversations with Susan Watts. It was the first time her name had been connected with Kelly in public, and it was later established that Gilligan had not only sent Chidgey excerpts from a recorded conversation, but also gave Chidgey questions to ask Kelly. The quote included Kelly’s opinion on the 45 minute claim. Chidgey asked Kelly if the quotes came from the meeting he had with Watts in November 2002—the only time the pair had met face-to-face; Kelly replied that “I cannot believe that on that occasion I made that statement”. According to Goslett, this was a truthful statement, as Kelly had not made the statement in November 2002, but on 30 May that year. Mangold notes that Kelly appeared to be under stress during the interview, and that some of the questioning was overtly hostile. One MP, Andrew MacKinlay, questioned Kelly towards the end of the session:

One of the witnesses who gave evidence to Hutton was David Broucher, the UK’s permanent representative to the Conference on Disarmament. In 2002 or 2003 he had asked Kelly what would happen if Iraq were invaded; Kelly had replied “I will probably be found dead in the woods”. Over the 24 days evidence was taken, the inquiry questioned 74 witnesses and received over 10,000 pages of evidence; most of the documents, along with transcripts of the questioning, were published online by the inquiry team. Hutton reported on 28 January 2004 and wrote:

In February 2003 Colin Powell, the US Secretary of State, addressed the United Nations Security Council to discuss Iraq’s WMD. He included information on mobile weapons laboratories, which he described as “trucks and train cars … easily moved and … designed to evade detection by inspectors. In a matter of months, they can produce a quantity of biological poison equal to the entire amount that Iraq claimed to have produced in the years prior to the Gulf War.” Following his examination of the vehicles in question, Kelly spoke, off the record, to journalists from The Observer. In their article in the newspaper on 15 June 2003 they described him as “a British scientist and biological weapons expert”, and quoted him as saying:

He continued that “The long-term threat, however, remains Iraq’s development to military maturity of weapons of mass destruction – something that only regime change will avert.” On 20 March 2003 British and American troops entered Iraq to bring about the regime change. Most of the country was occupied and the Saddam regime was overthrown within four weeks; Bush stated that war was over on 1 May 2003.

On 7 May 2003 Kelly was telephoned by Susan Watts, the science editor of the BBC’s Newsnight programme; the call lasted 15 to 20 minutes. They discussed various matters relating to Iraq including, towards the end of the conversation, the matter of the 45-minute claim. Watts’s handwritten shorthand notes showed Kelly stated the claim was “a mistake to put in. Alastair Campbell seeing something in there, single source but not corroborated, sounded good.” The pair also had a subsequent call on 12 May.

On 22 May 2003 Kelly met Andrew Gilligan, the Defence and Diplomatic Correspondent for BBC Radio 4’s Today programme, at the Charing Cross Hotel, London. It was the third time the pair had met. The meeting, initiated by Gilligan, was for the journalist to ask why Kelly thought WMDs had not been discovered in Iraq by the British and American troops. According to Gilligan, after 30 minutes the conversation focussed on the September Dossier and how key areas of the document were altered to give greater impact to the public. Gilligan took notes on an electric organiser; he said these read as

Soon after the meeting, Gilligan claimed, he wrote a full script of the interview, based on his memory and notes. Between the completion of the document and the start of the Hutton Inquiry in August, Gilligan says he lost that script. Kelly was in New York on 29 May 2003, attending the final commissioners meeting of UNMOVIC under the leadership of Hans Blix. At 6.07 that morning, on the Today programme, Gilligan explained to the programme’s host, John Humphrys, what he would be discussing later in the programme:

Hunt undertook the post-mortem examination on 19 July in the presence of eight police officers and two members of the coroner’s office. Hunt concluded that the cause of death was a haemorrhage caused by a self-inflicted injury from “incised wounds to the left wrist”, with the contributory factors of “co-proxamol ingestion and coronary artery atherosclerosis”. On 20 July 2003, the day after the post-mortem, the BBC confirmed that Kelly was their only source. Nicholas Gardner, the coroner, opened and adjourned his inquest on 21 July, noting that the pathologist was still awaiting the toxicology report. With the establishment of the inquiry under Hutton, the Lord Chancellor’s Department contacted Nicholas Gardner, the coroner, to advise him that under section 17A of the Coroners Act 1988, the coroner’s inquest should only be resumed if there were exceptional circumstances to do so.

On 6 August 2003, five days after the preliminary session of the Hutton Inquiry, Kelly was buried at St Mary’s Church, Longworth.

Lord Hutton, in the report to his inquiry, suggests that Kelly might well have been under consideration for a knighthood in May 2003. Kelly’s work in Iraq earned him a nomination for the Nobel Peace Prize; his biographer, the former MP Norman Baker, wrote of Kelly:

In March 2004 the Oxfordshire coroner, Nicholas Gardiner, convened a hearing to decide whether there were the “exceptional circumstances” needed to resume the inquest; he concluded that such circumstances did not exist and that an inquest was not required.

Despite the conclusion of the Hutton report that Kelly committed suicide, there was continued debate over the manner of his death. Several doctors questioned the conclusion on medical grounds, although their position has been doubted by pathologists. The former leader of the Conservative Party, Michael Howard, and the former Liberal Democrat MP, Norman Baker, both think Kelly was murdered. In 2007 Baker published The Strange Death of David Kelly in which he argued that Kelly did not commit suicide. Kelly’s family expressed their displeasure at the publication; his sister-in-law said: “It is just raking over old bones. I can’t speak for the whole family, but I’ve read it all [Baker’s theories], every word, and I don’t believe it.”

In 2007, information that no fingerprints were found on the knife that Dr Kelly supposedly used to kill himself was made public for the first time, thanks to a Freedom of Information request to Thames Valley Police (the same later turned out to be true about the blister packs of pills Dr Kelly supposedly ingested, and the water bottle he supposedly drank out of to help him swallow the pills).

In December 2009 six doctors applied to the Oxford coroner’s office to reopen the inquest, claiming that there was insufficient evidence for Hutton’s conclusion of suicide. Their request was turned down on legal advice, and they were informed that evidence relating to Kelly’s death was to be kept secret for 70 years. Hutton stated that he did so “solely in order to protect Dr Kelly’s widow and daughters for the remainder of their lives (the daughters being in their twenties at that time) from the distress which they would suffer from further discussion of the details of Dr Kelly’s death in the media”.

Kelly’s grave was a focal point for the campaign group “Justice for Kelly”, who left placards demanding an inquest and undertook vigils at the graveside. Following complaints by his widow and a request by her to the Diocese of Oxford, Kelly’s remains were exhumed in June 2017.