There is "no evidence" of third party involvement in the death of phone-hacking whistleblower Sean Hoare, police have confirmed.
Detectives now hope further toxicology tests will solve the mystery surrounding how the former News Of The World (NOTW) reporter came to die at his Watford home.
Mr Hoare's body was discovered on Monday morning after "concerns" about his welfare, police said.
A Hertfordshire Police spokesman said his death was being treated as "unexplained, but not thought to be suspicious".
Mr Hoare had claimed in an article for the New York Times that Andy Coulson "encouraged" him to hack phones.
He told the BBC's Panorama that phone hacking and other illegal practices were "endemic" at the NOTW.
"People were scared, so if you have got to get a story, you have got to get it and you have to get it by whatever means," he said.
When asked if he was subject to that pressure, he replied: "Yes of course I was, that is the culture of News International."
He also previously spoke out on BBC Radio 4's PM programme, saying that former editor Andy Coulson was "well aware that the practice exists."
"To deny it is a lie, simply a lie," he added.
Mr Coulson denies the allegations.
David Wooding, former political editor of the NOTW, told Sky News: "I worked with Sean on two papers, but our paths never crossed on the NOTW. He had long since left when I joined 18 months ago.
"We had worked before in the 90s on two other papers and he was a real Fleet Street character, a typical showbiz reporter out mixing with the stars every night.
"He would come in looking a complete wreck in the morning, because he had been out with the Gallaghers and people like that, and he knew all the inside gossip."
He went on: "We heard (the phone hacking revelations) a year or so ago when he claimed hacking was widespread.
"By then we knew about hacking because it had been blown open by the imprisonment of Clive (Goodman) and (Glen) Mulcaire and we all thought it was contained at that stage to a small group to showbiz type people who were fishing around for stories
"As far as I knew, Sean got his stories by good old fashioned journalism."
Mr Hoare was interviewed by police in September about the allegations but made no comment.
He was sacked by the NOTW over problems he had with drink and drugs.
A neighbour, who did not want to be named, said Mr Hoare struggled with alcohol abuse and had looked increasingly unwell in recent weeks.
The man said he knew Mr Hoare quite well because he would talk to him about his problems.
He said he was "paranoid" about people seeing him and was fearful of the police and the Government.