The discovery made headlines in December 2015, when the body of a man with no identity documents was found on the inhospitable moor in an apparent suicide. It took a year of investigation by police in nearby Oldham to finally establish that he was David Lytton, a 67-year-old Londoner who had flown from his new home in Pakistan in the days before his death. Tonight's Channel Four documentary, Mystery of the Man on the Moor, provides an exclusive insight into the case and has input from family members and friends. His younger brother Jeremy reveals that secretive David, who had Polish Jewish parents and Anglicised his birth name, was a student at the University of Leeds, studying psychology and sociology between 1966 and 1970. Despite being academically gifted and originally having had ambitions to study at Oxford or Cambridge, Lytton did not graduate and failed the course. He later worked as a London Tube driver, living in the Streatham area of the capital before selling his house for a large profit in 2006 and moving to the Pakistani city of Lahore. Incredibly, his brother thought he was living in California and a long-term girlfriend was not even told when he left the country. An open verdict on his death was recorded by a Manchester coroner. Although Lytton had ingested the notorious poison strychnine - known as the 'Agatha Christie' poison for its use in her novels - he had bought a return rail ticket back to London Euston and had it with him when he died. Lytton was collected at Heathrow by a friend and booked into a hotel for five nights, staying for only one. He appears to have told nobody else he was back in the UK, and had not bought a return flight. He was captured on CCTV at Manchester Piccadilly Station looking calm and unconcerned before travelling to the notorious Saddleworth Moor. The programme also reveals that his 18kg luggage allowance and passport have never been found. Police finally traced him in 2016, when they discovered his name on a passenger manifest from Pakistan to London after encountering several dead ends. Lytton has been buried in a Jewish cemetery in Manchester, but his associates are still puzzled by his decision to go to the Moor, as he was not thought to have links to the area. Mystery of the Man on the Moor airs tonight at 10pm.