The Hutton inquiry has heard about a series of e-mails sent by Dr David Kelly shortly before his death - including one warning of "dark actors playing games".
Dr Kelly is thought to have committed suicide
Assistant chief constable of Thames Valley Police Michael Page said they came across the e-mails as they searched the "vast amount" of computer equipment in Dr Kelly's home.
The inquiry is investigating the circumstances of Dr Kelly's death - he apparently committed suicide eight days after being named as the suspected source for a BBC report claiming Downing Street "sexed up" a dossier on the threat posed by Iraq.
ACC Page said the total memory in the computers was equivalent to a "pile of paper twice as high as Big Ben".
He said they seized one personal computer, a palm personal digital assistant, a Toshiba laptop, two Dell laptop computers, a cardstyle laptop which was faulty and one unused hard-drive. From the Ministry of Defence they seized another personal computer.
He said that police did a search of the computers using key words such as "suicide", "distress" and "Iraq".
A number of e-mails, written off-line, were all sent together at 1118 BST on 17 July, just over three hours before Dr Kelly set off for his final walk.
Among them was one to Gaeta Kingdom at Oxford University saying: "Many thanks for your thoughts and prayers. It has been a remarkably tough time. Should all blow over by early next week, then I will travel to Baghdad a week Friday. I have had to keep a low profile which meant leaving home for a week. Back now. With best wishes and thanks for your support. David"
The inquiry was shown further e-mails including one to Judith Millers saying: "Judy I will wait until the end of the week before judging - many dark actors playing games. Thanks for your support. I appreciate your friendship at this time."
ACC Page said he had made extensive inquiries as a result of the suggestion there were "many dark actors playing games".
He said that after a full investigation: "I remain confident that he met his death at his own hands."
The inquiry is to hear evidence later on Wednesday from two unidentified members of the defence intelligence staff.
The inquiry has already been told at least two members of the MoD's intelligence staff had reservations about the way some of the information in the dossier was presented.
The two unnamed officials called to the inquiry are likely to give evidence from a separate room via an audio link.
The government has always denied exaggerating the threat from Iraq and transforming the weapons dossier against the wishes of the intelligence services.
On Tuesday, Professor Keith Hawton, a psychiatrist who is an expert in suicide, said it was almost certain Dr Kelly had taken his own life because he felt he had been "publicly disgraced".
The forensic pathologist who carried out the post mortem examination on Dr Kelly's body after he was found with a slit wrist in woodland near his Oxfordshire home will also testify.
The first person to take the witness stand on Wednesday was toxicologist Richard Allan, who said Dr Kelly had taken "quite a large overdose" of Coproxamol, the prescription only-drug which his wife took for her arthritis.
About 30 tablets had been taken about an hour before Dr Kelly's death, he added.
Senior Foreign Office official Patrick Lamb, who has already appeared and told the inquiry he was a friend of Dr Kelly's, is also giving evidence again.
Mr Lamb said Dr Kelly had told him before the controversial report was broadcast on 29 May that he had spoken to Andrew Gilligan.
Mr Lamb said he passed this information on to the deputy head of the Defence Intelligence Service on 17 June.
Dr Kelly wrote to his line manager on 30 June to say that he had spoken to Mr Gilligan and believed that he might have been a source for the report.