Toxicology tests awaited as police rule out any third-party involvement in death of News of the World whistleblower

A postmortem into the death of the News of the World whistleblower Sean Hoare found no evidence of third-party involvement and confirmed that his death was non suspicious, the police have said.

No specific cause of death was given by the police, who said they were waiting for the results of toxicology tests and were continuing to examine "health problems" identified during the autopsy.

Hertfordshire police said the results were "inconclusive", but detectives could not rule out suicide until they knew the results of the tests, which could take weeks.

"There was no suicide note found at the scene," the spokesperson said. "We cannot categorically say one way or another whether this was suicide, as we have not got the toxicology results."

Hoare was the first named journalist to allege that the former News of the World editor Andy Coulson was aware of phone hacking carried out by his staff.

Hoare worked for the Sun and NoW with Coulson, before being dismissed for drink and drugs problems. He had spoken openly to a number of news organisations about the practice of phone hacking.

Hertfordshire police had previously said they were treating the death of 47-year-old Hoare as "unexplained but not thought to be suspicious".

In a statement released on Tuesday, the force said of the postmortem: "There is no evidence of third-party involvement and the death is non suspicious … there is an ongoing examination of health problems identified at the post mortem."

The postmortem was conducted by a Home Office-accredited forensic pathologist and it began at 2pm on Tuesday.

The examination was a section 20 autopsy, which would ordinarily be used in suspicious death cases. Hertfordshire police said this was just a precaution. "Because of the circumstances surrounding the case and the high-profile nature of the person believed to be involved, a decision was taken for a Home Office postmortem to take place to thoroughly investigate the matter," a spokesman said.

The former tabloid journalist is understood to have lived in a first-floor flat in Watford with his wife, Joanne.

Hertfordshire police, which asked its major crime unit to investigate the death, also answered questions concerning their approach after the discovery of Hoare's body on Monday. He was found dead in the flat at 10.40am. Neighbours said police and an ambulance were at the site until about 3pm. It was not until after 9pm, two hours after TV and website reports of the whistleblower's death, that more uniformed and plainclothes police, including scientific officers, arrived at Hoare's flat.

Police said the "log detailing response activity in relation to the incident shows clearly that the initial response to this incident was correct".

They added: "Throughout the day the tragic incident was treated as an unexplained but non suspicious death. As an additional measure, following a routine review of the incident and in light of a clearer understanding of the former position of the person, officers returned to the property to make routine follow-up inquiries, which are now ongoing. The incident continues to be treated as non suspicious."

Hoare returned to the spotlight last Tuesday after he told the New York Times that reporters at the NoW were able to use police technology to locate people via mobile phone signals, in exchange for payments to officers. He said journalists were able to buy mobile-phone tracking data from police for £300.

That evening Hoare had dinner with two New York Times journalists involved in the story – Don Van Natta Jr and Jo Becker. Van Natta Jr, via a web tweet on Monday night, said: "RIP Sean Hoare. Jo Becker and I had dinner with him last Tues night. He was ailing but defiant and funny. And no regrets. All-courage."

Hoare had given further details about "pinging" to Guardian journalists last Tuesday and Wednesday. He described how reporters would ask a news desk executive to get the location of a person. "Within 15 to 30 minutes someone on the news desk would come back and say 'right, that's where they are'. "

He added: "You'd just go to the news desk and they'd come back to you. You don't ask any questions. You'd consider it a job done."

Hoare repeatedly expressed the hope that the hacking scandal would lead to journalism "being cleaned up", and said he had decided to blow the whistle on the activities of some of his former NoW colleagues with that aim in mind.

Calls to Hoare's home phone on Thursday and Friday went unanswered.