The man was found by a cyclist on 12 December near a hill in the Greater Manchester area
A mystery man who was found dead on moorland in England before Christmas had strychnine, the highly toxic substance used in rat poison, in his system.
Detectives have been unable to identify the pensioner since he was discovered at a beauty spot near Oldham.
Aged between 65 and 75, he was found by a cyclist on 12 December near a hill known as the Indian's Head.
He was fully clothed and there was no sign of a struggle or a fall.
The man had travelled north from London the day before he was found. He left the city just after 9am.
He was next seen on CCTV at 9:50am, where he bought a return ticket to Manchester.
Arriving in Manchester at 12:07pm, he spent 53 minutes wandering around the station before heading into the city centre.
Later, he was seen at a pub asking the landlord how to get to the top of the hill.
He was not wearing walking clothes.
He had a northern accent but it was not local.
At about 4:30pm he was spotted by a motorist near where he was found the day after, around three quarters of the way to the top of the hill.
There were three train tickets in his pockets, including the return to London Euston, plus £130 in ten pound notes.
He was not carrying a mobile phone, and there were no identifying documents.
Detectives say he was white, of slim build, with grey hair and a receding hairline.
He was wearing a brown heavy jacket, blue jumper, white long-sleeved shirt, blue corduroy trousers and black slip-on shoes.
While a toxicology report has now revealed what the man died of, police still do not know who he was.
An initial theory concerned a plane crash in 1949 near to where he was found, in which 24 people died.
Two children survived - two-year-old Michael Prestwich, who died 10 years later, and five-year-old Stephen Evans.
Mr Evans, now a university professor, has since spoken to police.
Another theory was that the man had been suffering from a serious illness.