Kamar Mahtum told AFP after returning to Malaysia that her long-lost sister Siti Aishah Abdul Wahab, 69, looked "healthier than me" despite reports of sordid modern-day slavery that have shocked Britain.
"No, she can't be, she looked so well," the 73-year-old said when asked during a telephone interview if Siti Aishah had been a slave at the Maoist "collective".
Kamar, who met with Siti Aishah for 90 minutes after being taken by car to a location six hours from London on Thursday night -- she believes it to be around Manchester -- said her sister was physically, mentally and emotionally fine.
Siti Aishah came to Britain as a high-flying student in around 1968 but turned her back on her family after joining a radical left wing group.
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The other women allegedly held by the couple are believed to be the daughter of a World War II code-breaker who also became a communist, and a 30-year-old who has spent her entire life inside the Maoist "collective".
British police had for the first time last Wednesday interviewed the three women, as fresh details of their secretive commune emerged.
The women were "freed" on October 25 after one contacted a charity that usually deals with forced marriage and honour-based violence.
Their alleged captors, named by media as 73-year-old Aravindan Balakrishnan and his 67-year-old wife Chanda, have been freed on bail pending further investigations.
Kamar said Siti Aishah seemed to have no regrets about joining the "sect" but "was probably influenced by the man's hypnotic power", referring to Aravindan.
Police believe the women were brainwashed and possibly beaten, but not sexually abused.
It appears that they were occasionally allowed out of the house, and detectives are working to understand the "invisible handcuffs" that were used to control them.