David Kelly - named as the mole who said the case for war was "sexed up" - was found dead in a field yesterday morning.
Angry friends said the mild-mannered expert had been left devastated by his treatment at the hands of Labour's spin machine and the Ministry of Defence.
Mr Blair was so shaken by the tragedy he immediately ordered a judicial inquiry.
The roles of communications director Alastair Campbell and Defence Secretary Geoff Hoon are under scrutiny.
Father-of-three Dr Kelly, 59, denied being the source for a BBC story which said the Government's dossier had been "sexed up" to include the claim that Saddam Hussein could use WMD within 45 minutes.
MPs said he was a "fall guy" and had been "thrown to the wolves" when he appeared before a Commons select committee.
Dr Kelly disappeared after telling his wife he was going for a walk. When he did not return home, police were informed and a search began.
At 9.20 yesterday morning, officers found a body face down by a copse at Harrowdown Hill, five miles from Dr Kelly's home in Southmoor, Oxfordshire. It was described as a "grisly find", but police did not say how Dr Kelly died.