MP investigates Dr Kelly's death
Lib Dem Norman Baker said the 2003 Hutton inquiry had "blatantly failed to get to the bottom of matters".
And he vowed to quiz ministers and unearth new facts to establish the "truth" of the case.
Dr Kelly was found dead after being named as the possible source of a BBC story on the government's Iraq dossier.
Mr Baker, who is known for his forensic use of parliamentary questions, said he had quit his front bench role partly to concentrate on investigating the scientist's death.
"It struck me as extremely odd at the time that Dr Kelly was thought to have committed suicide in the way he did, at the time he did," Mr Baker told the BBC News website.
"The more I look into it the less convinced I am by the explanation and the more unanswered questions appear which ought to have been addressed properly by the Hutton inquiry or by the coroner."
Mr Baker said he thought Dr Kelly had been "badly treated by the government" and part of his motivation in investigating the scientist's death was to "clear his name".
An inquest into Dr Kelly's death was opened and adjourned in July 2003.
The task of investigating the "circumstances surrounding the death" of Dr Kelly was then handed to Lord Hutton, who, following a two month inquiry, concluded the scientist had taken his own life.
Oxford coroner Nicholas Gardiner looked into the possibility of reopening the inquest into Dr Kelly's death.
But after reviewing the evidence with the Lord Chancellor, including material that had not been presented to the Hutton inquiry, he concluded, in a March 2004 hearing at Oxford coroner's court, there was no case for reopening the inquest.
Mr Gardiner said he accepted this would "do little to put an end to the controversy relating to the death of Dr Kelly" but he was satisfied there was no need for further investigation.
Mr Baker said he believed Lord Hutton's inquiry had become preoccupied with a row between the government and the BBC, leaving important questions about Dr Kelly's death unanswered.
"The most important unanswered question is why he would have wanted to commit suicide, which still hasn't been addressed," said Mr Baker.
There was also a question mark over the method Dr Kelly apparently used to commit suicide.
Given his knowledge of the human body, said Mr Baker, it is unlikely the scientist would have decided to kill himself by "slitting a rather hidden artery in his hand".
He said he had established through a parliamentary question that only one person in 2003 had committed suicide this way, which "presumably" was Dr Kelly.
Other puzzles include the fact that although Dr Kelly had supposedly taken 29 co-proxamol painkillers only "a quarter of one tablet" was found in his stomach, said Mr Baker.
He said he also wanted to know why the police hunt for Dr Kelly had apparently been launched before the scientist had actually left his house on his final walk, let alone been reported missing.
There were also questions about the time of Dr Kelly's death and the procedures followed at his post mortem.
And Mr Baker said he was also interested in the wider political implications of the scientist's death.
"There were unanswered questions about the way the government conducted itself which got lost in the mire of how the BBC was behaving," he said.
Mr Baker, whose parliamentary question about the Hinduja brothers was the catalyst that led to Peter Mandelson's second resignation from the Cabinet, has been tabling questions to ministers in an effort to establish some basic facts about the Kelly case.
He has also been speaking to medical and legal experts about the case and now wants to speak to anyone who feels they have new evidence.
"I am asking for people to come forward who have knowledge of the facts - knowledge or information which they think should be properly considered and ultimately in the public domain and if they do so I will treat them in confidence."
He said people who thought they could help should write to him at his House of Commons office.
The Lewes MP, who was recently replaced as Liberal Democrat environment spokesman by Chris Huhne, stressed he did not want to speculate about alternative explanations for Dr Kelly's death at this stage.
"The facts do not support suicide, as set out, but nor do they necessarily support anything else and therefore those unanswered questions are what I'm looking in to."
He also said he was keen not to cause unnecessary distress to Dr Kelly's family.
"I have no wish to upset the family in any way and I hope that nothing I am doing is doing that. The fact of the matter is, in this most important of issues, there is a general feeling around that the facts have not been fully explored or revealed."
But he said the Kelly affair was "unfinished business" and there needed to be "political closure" on it.
"The public out there can smell a rat and they don't think it's finished business either," the MP added.