Lord Hutton's interventions in the inquiry hearings have shown he is particularly interested in the intense pressure David Kelly was put under in the months leading to his apparent suicide.
The hearings have already been told that the scientist was responsible for an earlier damaging report by Andrew Gilligan.
But the new evidence discloses that a Metropolitan Police investigation into whether Kelly passed top-secret documents to Gilligan was dropped only a little more than a week before he died.
The seriousness of the situation Dr Kelly could have found himself in was underlined by an internal Ministry of Defence memo calling for a "damage/assessment impact statement if Kelly was to be arrested".
Officials were also discussing whether to agree to a "draconian" police request to interrogate the scientist. John Cochrane, of MoD security, wrote: "We are to resist any attempt by the police to interview Kelly or anyone who has interviewed him."
The suspicion is that the MoD feared a police cross-examination could have enabled Dr Kelly to air his wider reservations about the case for war.
Dr Kelly knew he was suspected of the leak. It is not clear, however, whether he was aware of the involvement of the police. If he was, then he could have feared prosecution under the Official Secrets Act.
The MoD insists that it wanted Kelly to appear privately before the intelligence and security committee (ISC) rather than a public session of the foreign affairs select committee (FAC).
But Tom Kelly, the Prime Minister's official spokesman, was keen for his namesake to face the traumatic experience of being thrust into the spotlight.
In an email to Jonathan Powell, Tony Blair's chief of staff, he said: "The MoD tell me there is a possibility that Dr Kelly may appear before the ISC rather than the FAC. But the latter would surely be better, because if Kelly appears next Tuesday, they could recall Gilligan next Wednesday."
A memo to Mr Powell from John Scarlett, the chairman of the joint intelligence committee says: "I am sure that he [Dr Kelly] does need careful briefing in advance, especially for the public sessions of the FAC. His views are supportive of our key assessments, but he will be sceptical about the trailers [which the Government said could be weapons laboratories]."Reuse content