Mystery remains over why a man from London took rat poison on a bleak moor in northern England two days after flying back to the UK, an inquest concluded.
David Lytton prompted a massive police investigation and an international hunt for clues sparking interest across the world as his identity remained unknown for 13 months, Rochdale Coroner's Court was told.
But on Tuesday an open verdict was recorded by Simon Nelson, senior coroner for Greater Manchester North, who said a series of "fundamental questions remain unanswered" over the death of Mr Lytton.
Originally from London, he flew 4,000 miles from his adopted home in Pakistan, booked into a hotel for five days in the capital then paid for a return train ticket to Manchester, went to a pub near Saddleworth Moor, asked the landlord the way to "the top of the mountain" and wandered off into the dark to take strychnine.
He was wearing a light mac, trousers, a shirt and slip-on shoes and had no connection to Saddleworth.
The 67-year-old was found fully clothed on a remote track near Indian's Head, the summit above Dovestone Reservoir, on December 12 2015.
Carrying £130 in cash but with no identification on him and despite a mass media appeal he was only identified in January, more than a year after his death.
Mr Lytton had been in a relationship for more than 30 years with a woman, the inquest heard, but did not even tell her he was moving to Pakistan in 2006 and simply left.
Another friend of his did not even know of her existence.
He had also not spoken to his only brother for more than 10 years before his death.
Though highly intelligent, he was also a complex man who "compartmentalised" his life and friendships, the inquest heard.
Coroner Mr Nelson said he was satisfied there was no third party involvement in Mr Lytton's death and that he had taken the poison "by his own hand."
But he said there was no way of knowing his intention. He had booked a hotel for five nights in London, bought a return train ticket, had no connection to Dovestone Reservoir, and was "inadequately and inappropriately" dressed to go walking in winter on the moors.
And it was not known where he had got the strychnine or "his prevailing intention" before ingesting the poison.
Mr Nelson, concluding the four-hour inquest, added: "This has been an extra-ordinary case for obvious reasons.
"Sadly, notwithstanding the quite outstanding investigative work by the police, there are many fundamental questions which remain unanswered.
"He was a highly complex, private individual who tended to compartmentalise his life or not reveal or share his thoughts or future plans."
Police had launched an international hunt to identify Mr Lytton, focusing eventually on Pakistan, when a post-mortem examination revealed he had a titanium plate in his leg which was only manufactured and fitted in Pakistan.
A study of data from flights between Pakistan to London revealed that a passenger with a striking resemblance to the artist's impression of the mystery man had travelled from Lahore to London on December 10 2015.
DNA analysis confirmed "Neil Dovestone" - a nickname given to him by mortuary workers at Royal Oldham Hospital - was actually Mr Lytton, from London.
The inquest heard he had been born David Lautenberg, the family changed their name to Lauten, and he later changed his name again to Lytton, growing up in Finchley, north London.
Younger brother Jeremy Lauten described him as a "genius" who did well at grammar school and wanted to become an Oxbridge student.
But he failed to get the grades and eventually dropped out of a sociology and psychology degree at Leeds University, and became ever more "insular" and distant from his family.
He became a croupier and later a Tube driver on the London Underground - so he could spend all day in the cab on his own without speaking to people.
He had a house in Streatham but lived a "minimalist" life "unencumbered with possessions" and his home was virtually empty, he only spent money on his personal appearance and was "very exacting" in how he looked.
Mr Lauten said his brother did not attend their father's funeral and they had no contact from 2004.
But Mr Lauten was emphatic his brother would not take his own life.
In a statement Maureen Toogood, a nurse, said she was in a relationship with Mr Lytton from 1972 though they never lived together due to his "unusual character traits".
She described him as shy, though particular about his appearance, and he asked her to never talk to him about his family.
His house was "devoid" of any furniture but he was not short of cash.
Ms Toogood became pregnant and the couple were excited but she miscarried and the relationship was never the same, she said.
In October 2006 he visited her as normal and later kissed her goodbye and left - she never saw him again.
She was "flabbergasted" to find out from a neighbour he had sold his house and left the UK to live in Lahore without saying a word to her.
Mr Lytton lived in Pakistan from 2006 until his return in 2015.
He had outstayed his visa and spent five days in jail on one occasion when he tried to return to the UK with out-of-date documents.
Old friend Salim Akhtar described his friend as "highly intelligent" but "very private" and a "loner" who had a "difficult" relationship with his family and never mentioned his relationship with Ms Toogood during their 40-year friendship.
Mr Akhtar picked him up from Heathrow Airport when he returned to the UK for the last time.
In a statement he said: "He told me he was thinking of going travelling. He was very relaxed.
"I did not hear from David again, it did not come as a surprise because that's how David was.
"He was just going off to do his own thing without any warning."