A Home Office post-mortem examination has been carried out on Wigan man John Peter Heyes, whose body was found in marshlands in Marsh Green on Sunday, but the findings were inconclusive.
Detectives are awaiting further forensic analysis and toxicology results.
Shortly after 3.15pm on Sunday, police were called to reports that the body of a man had been found in marshland in Marsh Green.
Emergency services attended but sadly the man - who has since been formally identified as 35-year-old John Peter Heyes - was pronounced dead at the scene.
No arrests have been made and enquiries are ongoing.
Detective Chief Inspector Clare Devlin, of GMP’s Wigan borough, said: “Sadly we can’t conclusively say what caused John’s death at this stage but we remain determined to provide his family with answers.
“We have specialist officers supporting John’s family at this incredibly difficult time and our thoughts remain with them as we carry out our enquiries and try to piece together the circumstances surrounding his death.
“Our investigation is very much ongoing and I would urge anyone that saw anything suspicious in the local area over the weekend, or anyone with any information to please get in touch.”
Anyone with any information is asked to contact police on 0161 856 5307, alternatively call 101 or the independent charity Crimestoppers on 0800 555 111.