Attorney General Dominic Grieve has ruled out asking the High Court to order a new inquest into the death of weapons expert Dr David Kelly.
The scientist's body was found in woods close to his Oxfordshire home in 2003, shortly after he was named as the source of a BBC report casting doubt on the government's claim that Iraq had weapons of mass destruction capable of being fired within 45 minutes.
An inquiry by Lord Hutton in 2004 concluded he had committed suicide, but a campaigning group of doctors denounced it as a "whitewash", claiming the verdict was a cover-up.
In a statement to the Commons on 9 June 2011, Mr Grieve backed the original inquiry's findings telling MPs the evidence that Dr Kelly took his own life was "overwhelmingly strong".
He said: "There is nothing I have seen that supports any allegation that Dr Kelly was murdered or that his death was the subject of any kind of conspiracy or cover-up.
"In my view, no purpose would be served by my making an application to the High Court for an inquest, and indeed I have no reasonable basis for doing so."
There is no possibility that an inquest would return a verdict other than suicide, he concluded.
Labour accepted the attorney general's decision and agreed there was a "lack of new compelling evidence" that the government weapons inspector had not committed suicide.
Shadow solicitor general Catherine McKinnell called on Mr Grieve to make public a brief outline of the legal basis of his decision.
She also urged him not to rule out a future inquest should any "new and compelling evidence" about the circumstances surrounding Dr Kelly's death come to light.
Tory MP Richard Ottaway, current chair of the Foreign Affairs Committee, which took evidence from David Kelly in 2003 under the chairmanship of Labour's Donald Anderson, said he "never doubted" Dr Kelly had committed suicide. It was time to bring closure to the matter, he added.