He was described as a "quiet chap" when he was a student, first at Raffles Institution (RI) and later at the then University of Singapore.
Aravindan Balakrishnan, 73, was arrested last week for holding three women as domestic slaves in London for 30 years.
When heart doctor Low Lip Ping read the news, he thought it could be the same Aravindan who was his classmate in Form Two at RI. Form Two was the equivalent of today's Secondary One.
"But then again, it could have been someone else with the same name. Aravindan was as normal as any Form Two boy. There was nothing unusual about him then," Dr Low said.
Aravindan, who is reported to have been leading a Maoist "cult", had his Singapore citizenship - which was registered in 1960 - revoked in 1977. By then, he was already living in London.
Singapore's Home Affairs Ministry had accused him of engaging in "activities which are prejudicial to the security" of the country, after he was named a radical "closely associated with Eurocommunists".
Another one who "vaguely remembered" him was former People's Action Party Member of Parliament for Ang Mo Kio GRC Lau Ping Sum.
They were in the same year in the Arts faculty of university.
"I didn't know him very well as I did not get to talk to him. He was small in stature and did not say much in class," Mr Lau told The New Paper.
As the number of university entrants was small, The Singapore Free Press used to list the names of candidates selected for tertiary education.
A check of the April 7, 1960 issue found Aravindan listed among those entering the Arts faculty.
When contacted, many of his peers at the university could not remember him.
Aravindan is believed to still have family members here.
Attempts by TNP to contact them were unsuccessful.
British community worker Dudley Heslop, 59, who went to a series of lectures by Aravindan told Britain's Evening Standard that he treated his followers like army recruits, and took their money and property for his cause.
Mr Heslop said members of the cult were forced to cut off contact with their families and faced severe discipline if they breached any of his strict rules.
He said: "Women abandoned their careers and their futures for him. They had to put him and the collective before their families.
"He would take the wages of others for the collective, he was in control."
Aravindan, known as Comrade Bala, was a senior member of the Communist Party of England, but he split from the party in 1974, reported the Guardian.
That year, he founded the Workers' Institute of Marxism-Leninism-Mao Zedong Thought.
Professor Steve Rayner, from Oxford University, who wrote extensively about the group told the Daily Telegraph: "They were a tiny, very tight-knit group clearly under the spell of their leader.
Their membership was overwhelmingly overseas in origin.
"Most were foreign students who seemed to have difficulty adjusting to life in the UK. They refused to recognise the legitimacy of the state and state institutions and maintained a hostile attitude towards the establishment and towards the rest of the far-left in Britain at that time. Their ideology was profoundly detached from reality."
Aravindan and his wife Chanda, a Tanzanian, came to the authorities' notice when one of the three women they held captive contacted a charity that usually deals with forced marriages and honour-based violence, reported AFP.
Police in Kuala Lumpur have identified one woman as 69-year-old Malaysian Siti Aishah Abdul Wahab, who went to Britain as a student around 1968 before joining the radical left and turning her back on her family.
Her sister, Madam Kamar Mahtum, boarded a flight to London on Wednesday, hoping to be reunited with her.
Ms Siti Aishah was reportedly so drawn in by Aravindan's Marxist rhetoric that she dumped her fiance and moved in with the collective.
British media said she suffered a stroke recently, but was not receiving treatment - and that this was what pushed the women to ask for help.
The Daily Telegraph newspaper identified the second woman as 59-year-old Josephine Herivel, whose father John was one of the Bletchley Park codebreakers who helped Britain and its allies win World War II. She is believed to have moved to London in the 1970s and disowned her family after becoming involved with the far-left.
The third woman is thought to be the daughter of a commune member who died in 1997. Rosie, who also goes by the name Prem Maopimduzi Davies, is believed to have spent her entire life in the commune with little contact with the outside world.
- Additional reporting by Judith Tan
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