Hoare had made allegations that the practice of phone hacking was far more extensive than the News of the World acknowledged when police first investigated the claims.
Hertfordshire Police said the body of a man was found at a property in Langley Road, Watford, on Monday morning.
A police spokesman said the death was currently being treated as unexplained, but was not thought to be suspicious.
The spokesman said: “At 10.40am today police were called to Langley Road, Watford, following the concerns for welfare of a man who lives at an address on the street.”
“Upon police and ambulance arrival at a property, the body of a man was found. The man was pronounced dead at the scene shortly after.”
“The death is currently being treated as unexplained, but not thought to be suspicious. Police investigations into this incident are ongoing.”
Mr Hoare had previously told the BBC’s Panorama TV documentary programme that phone hacking was “endemic” at the News of the World.
He also said the then News of the World editor Andy Coulson had asked him to hack phones – something Mr Coulson has denied.
There seems to be a daily resignation list at the moment. Today the Police Assistant Commissioner John Yates has resigned a day after his boss Sir Paul Stephenson stepped down.
This phone hacking thing has claimed more victims than the guillotine now and we are still waiting for some hard evidence to be made public. There must be some out there because all these people do not fall on their swords for nothing?