Over the next two months, a long series of witnesses will be called to a bland-looking room, attached to the Royal Courts of Justice in central London, to give evidence that could destroy Blair's reputation.
Among those due to be called before senior judge Brian Hutton are a string of government officials, ministers and - eventually - Blair himself.
Kelly was found with a slit wrist near his home in Oxfordshire, southern England, just over three weeks ago. But an unofficial political truce in place since then appeared already to be unravelling on Sunday.
The run-up to the government weapons expert's suicide highlighted a “culture of duplicity and deceit” in Blair's government, charged a senior member of the opposition Conservative party.
The country had “a prime minister who's a stranger to the truth and a government that's rotten to the core,” finance spokesman Michael Howard said.
PM damaged by WMD controversy
Kelly's death came after he was identified as the main source for a controversial BBC report in May. The BBC claimed Blair's staff exaggerated intelligence data on Iraq's weapons of mass destruction before the US-led war.
The weapons expert was revealed as having briefed Andrew Gilligan, a BBC radio reporter, who alleged that the government deliberately "sexed-up" a dossier last September on Iraq's weapons.
Blair was the United States' closest ally in the war to unseat Saddam Hussein, launched in March. Repeated claims that Blair duped a sceptical country over the case for the conflict have caused him severe political damage.
The truth or otherwise of the intelligence about Saddam's alleged illegal weaponry will not come under the remit of Lord Hutton's inquiry. The probe was officially opened on 1 August, but proceedings effectively begin today.
Nonetheless, the possibility that ministers or officials deliberately tried to deflect attention from the weapons row by starting a war of words with the BBC - culminating in Kelly's death- would be almost as damaging.
Defence minister expected to fall
Blair was on Sunday coming under fire from all sides.
"The latest crisis for the government stems entirely from its obsession with presentation over substance," said Peter Kilfoyle, a member of parliament from Blair's ruling Labour party.
Blair - currently on holiday in Barbados - is considered very unlikely to lose his job immediately. But one of his most trusted ministers might not be so lucky, according to reports on Sunday.
Defence Secretary Geoff Hoon was being lined up as the government's "fall guy" for allegedly authorising the identification of Kelly as the source for the BBC story, the Sunday Express said.
"He (Hoon) is going to be hung out to dry in the hope that his resignation will get Tony Blair off the hook," an unnamed government source was quoted as saying.