Detectives are hoping toxicology results will shed light on the death riddle of a senior Tory in a Glastonbury Festival VIP toilet.
Christopher Shale, 56, a close friend of David Cameron, was discovered slumped in a cubicle in the backstage area on Sunday morning. The Prime Minister's constituency chairman had been reported as missing by worried family members at 900-acre Worthy Farm on Saturday.
It is feared his body may have lain undiscovered for up to 10 hours.
Police found his body as he was quoted in the Mail on Sunday bemoaning difficulties his party faced in recruiting new members. He was reported to have written: "No reason to join. Lots of reasons not to."
Downing Street was understood to have contacted Mr Shale on Saturday to warn him that the note he had written had been leaked to the newspaper.
Mr Cameron said he was "devastated" as he described Mr Shale as a valued friend and a "big rock" in his life.
Confusion reigned at the site after Michael Eavis said the wealthy businessman's death could be a "suicide situation". But police dismissed the claim, with sources saying he was thought to have suffered a heart attack.
A police spokesman said: "The results of the post-mortem combined with the inquiries conducted into the circumstances surrounding the death indicate it is not suspicious.
"Therefore Avon and Somerset Police are not treating the death as suspicious. Further tests will be conducted to establish the exact cause of death."
Festival founder Mr Eavis expressed his "deepest sympathy" as the police probe was launched.