What you need to know:
- In 2008, Sobhraj married Nihita Biswas -- 44 years his junior and the daughter of his Nepalese lawyer -- in a secret prison ceremony.
Notorious French serial killer Charles Sobhraj, the titular "Serpent" of the hit Netflix drama series, was responsible for a string of murders throughout Asia.
The charismatic conman, 78, was for nearly two decades serving a life sentence in Nepal for killing two tourists in Kathmandu in the 1970s.
He was freed from prison on health grounds on Friday, and was due to be deported to France within 15 days.
After a troubled childhood and several prison terms in France for petty crimes, he began travelling the world in the early 1970s, befriending and robbing young backpackers as he made his way along the drug-fuelled Hippie Trail from Europe to Southeast Asia.
He eventually arrived in Thailand, where he was implicated in his first murder, that of a young American woman whose body was found on a beach in Pattaya in 1975.
"He was cultured, courteous," said Nadine Gires, who befriended Sobhraj when he moved into her Bangkok apartment building that year.
But she soon began to fear her fast-talking neighbour, who masqueraded as a gemstone trader to lure cash-strapped travellers before drugging, robbing and killing them.
"Many people were getting sick in his home," she told AFP last year. "He was not only a swindler, a seducer, a robber of tourists, but an evil murderer."
Sobhraj -- a French citizen of Vietnamese and Indian parentage, who spoke several languages -- was linked to more than 20 killings in total.
His victims were strangled, beaten or burned, and he often used the passports of his male victims to travel to his next destination.
Sobhraj's sobriquet, "The Serpent", came from his ability to assume other identities in order to evade justice.
His exploits were dramatised in a TV series by the same name, a BBC and Netflix joint production that was watched by millions around the world.
The law caught up with Sobhraj in 1976 in India, where was sentenced to 12 years in prison.
From his jail cell, Sobhraj sold his story to a publishing house and was interviewed by Australian journalist Julie Clarke, recounting the murders in chilling detail and holding nothing back.
"He despised backpackers, he saw them as poor young drug addicts," Clarke told AFP in 2021.
"He considered himself a criminal hero."
Sobhraj ultimately spent 21 years in jail with a brief 22-day break in 1986, when he managed to slip out of his cell after feeding the guards cakes, cookies and grapes laced with sleeping pills.
He was caught in a restaurant in the Indian coastal state of Goa, where he had reportedly been riding around on a pink motorbike in outlandish disguises.
Later, he would claim the escape was a well-crafted plan to have his sentence extended to avoid extradition to Thailand, where he was wanted for multiple murders and could have faced the death penalty.
The two countries' extradition treaty expired in 1995 and he was released two years later.
'Sir Charles' behind bars
By then in his fifties, Sobhraj retired to Paris, where he led a mostly quiet life -- though if journalists came knocking, he would charge thousands of dollars for an interview about his notorious years in Asia.
He resurfaced in 2003 in Nepal, where he was spotted in Kathmandu's tourist district and arrested a few days later in an all-night casino.
A court there handed him a life sentence the following year for killing US tourist Connie Jo Bronzich in 1975. Her body was found with multiple stab wounds and having been severely burned.
It took Nepal's glacial legal system another decade to also sentence Sobhraj for the murder of her Canadian travelling companion, Laurent Carriere, whose passport he had used to escape Nepal after killing the pair.
In prison, Sobhraj reportedly lived in relative comfort, provided with a foam pillow, mineral water and meals from a Kathmandu restaurant.
He had also managed to extract similar perks from jail officials in India, earning him the nickname "Sir Charles" among other inmates.
In 2008, Sobhraj married Nihita Biswas -- 44 years his junior and the daughter of his Nepalese lawyer -- in a secret prison ceremony.
On the back of the notoriety brought by the wedding, Biswas starred in India's hugely popular version of the television show "Big Brother" in 2011.
Sobhraj has at least one daughter from a previous relationship who lives in France.