The judge investigating the events surrounding the death of weapons expert Dr David Kelly has opened his inquiry and confirmed his intention to to call Tony Blair as a witness.
Lord Hutton stressed he would not be conducting a trial
Lord Hutton began by telling a packed court room the inquiry had been prompted by a "very tragic death" and it would be fitting to stand for a minute's silence.
The senior judge spent the first 35 minutes of the session at London's Royal Courts of Justice explaining how he would conduct the inquiry and who he would call to give evidence.
Witnesses are to include the prime minister, the Defence Secretary Geoff Hoon, BBC journalist Andrew Gilligan and Dr Kelly's widow.
No firm timetable has been set, but the inquiry is due to resume on 11 August, after Dr Kelly's funeral on Wednesday.
Lord Hutton gave a brief synopsis of events leading up to the apparent suicide of the government scientist who was found dead a few days after appearing before a committee of MPs.
He said his task was to investigate the circumstances surrounding his death, quickly and fairly.
He also revealed Dr Kelly's body had been found with four electrocardiogram pads on his chest - one of the issues he wished to resolve.
Dr Kelly had a coronary artery disease which may have speeded up his death though not caused it, the pathologist reported.
Lord Hutton said the post mortem investigation found Dr Kelly had removed his watch and glasses before he died, which suggested deliberate self-harm.
Dr Kelly was at the centre of a row between the government and the BBC over claims about Iraq's weapons capability.
He died days after giving evidence to the Foreign Affairs Select Committee which was investigating the government's justification for war with Iraq.
He told them he did not think he was the main source for a BBC report alleging the government had "sexed-up" a dossier on weapons of mass destruction.
But after his death the BBC confirmed he was the source - although his name had already been widely circulated in the media before he died.
A letter from Dr Kelly to his line manager confirming he had met Andrew Gilligan was revealed by the inquiry on Friday.
In it he said he believed his account to the journalist may have been "embellished".
The Hutton inquiry will aim to establish how Dr Kelly's name was made public and what precisely he told journalists.
At the first session Lord Hutton set out the powers of the inquiry and gave a brief run through of the facts of the case established so far.
BBC chairman Gavyn Davies
BBC defence correspondent Andrew Gilligan
BBC science correspondent Susan Watts
BBC news correspondent Gavin Hewitt
Donald Anderson MP
Ann Taylor MP
Dr Kelly's widow, Janice
Other relevant government officials
He also detailed some of the questions that the key players in the case would have to answer.
Lord Hutton said he was inclined to allow a certain amount of cross-examination of witnesses where he believed that it would be "helpful" to the inquiry.
But he stressed that he was not in the business of conducting a trial.
Tony Blair is set to become only the second serving prime minister to appear
in public before an official inquiry when he gives evidence to Lord Hutton.
TV cameras were allowed to film Lord Hutton's opening statement but the inquiry then went off air as Geoffrey Robertson QC, representing ITN and Sky, made an application for the evidence of key witnesses to be broadcast.
Jeremy Gompertz QC, for the Kelly family, said the presence of TV cameras at the inquiry would only "intensify their ordeal".
Lord Hutton will announce his decision when the inquiry reconvenes.
Full transcripts from each day's session will be published on the inquiry's website.
It is hoped Lord Hutton's findings will be reported before the end of the year.