On Wednesday night the documentary The Mystery of the Man on the Moor will look at the investigation surrounding the death of David Lytton.
The Channel 4 programme will follow the police investigation which began after Mr Lytton's body was found near Dovestone reservoir on Saturday, December 12, 2015.
Mr Lytton was discovered by a cyclist lying on a track close to the summit of Indian’s Head above the reservoir.
The 67-year-old had travelled to the spot from London.
He had earlier been seen in the Clarence Pub pub in Greenfield, asking the landlord about the best way to ‘the top of the mountain’.
He then wandered off into the dark.
An open verdict was recorded by coroner Simon Nelson at an inquest into Mr Lytton's death on Tuesday.
He said a series of ‘fundamental questions remain unanswered’ over Mr Lytton’s death and was satisfied there was no third party involvement, with the poison taken ‘by Mr Lytton's own hand’.
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But he added that there was no way of knowing his intention.
Where is Dovestone reservoir?
The picturesque Dovestone reservoir sits near Saddleworth Moor, on the outskirts of Oldham and just 15 miles from Manchester city centre.
The area, known by many simply as Dovestones, is popular with families, walkers and cyclists.
As well as the picturesque reservoir, there are also a number of walks which lead up to the moors and the nearby Pennine Way.
The reservoir is next to the small village of Greenfield. On the day before Mr Lytton died, he was seen at The Clarence Pub in the village which is a five minute walk from Dovestones.
Who was David Lytton?
Police said David Lytton, 67, had no obvious connection to the area.
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He is believed to have been born to Sylvia and Hyman Lautenberg in 1948. His mother’s family are believed to be originally from Poland and of Jewish descent, the Guardian claimed.
It is thought he grew up in Streatham, south London.
Mr Lytton studied Sociology and Psychology at Leeds University between 1966 and 1970 and was expected to do extremely well, being classed as a ‘A grade student’.
He was described at his inquest as ‘a genius’ who did very well at school but also ‘a loner’ who would prefer his own company.
However an undiagnosed medical problem meant he had struggled to finish his university course.
Police discovered that he changed his name from David Kieth Lautenberg to David Lytton on June 18, 1986.
He worked as a London underground tube driver until 2005.
Speaking at the inquest, Mr Lytton's brother said he lost contact with him in 2006
His inquest heard Mr Lytton had been in a relationship with Maureen Toogood, from Blackheath, for 34 years from 1972.
The couple never had children and Ms Toogood last saw him on October 3, 2006.
Three days after this day a neighbour called her to say Mr Lytton had sold his home and moved to Pakistan.
He lived there until 2015, but had struggled with visa problems. While he was in Pakistan he had a titanium plate fitted in his left leg - this would later prove key information for police.
He bought a plane ticket back to the UK on December 5, 2015 and left on the first flight back to the U.K on December 10.
How did he die?
Mr Lytton’s body was discovered high up on the Chew track above Dovestones reservoir in a remote location.
He was found with no driving licence, bank cards or letters. But he did have on him £130 in cash, train tickets, and a small empty bottle with a cardboard container.
Toxicology tests on Mr Lytton following his death showed he had the poison strychnine in his system.
The highly toxic substance, which is used in rat poison, was though to be the likely cause of death.
It is now known how Mr Lytton obtained the strychnine.
The coroner at the inquest said he was satisfied there was no third party involvement in Mr Lytton’s death and said he had taken the poison ‘by his own hand’.
But he added that there was no way of knowing his intention.