The frail 96-year-old founder of The Family – a cult that stole children through adoption scams and imprisoned them at a house beside Lake Eildon from the early 1970s until 1987 – has suffered from dementia since 2007, rendering her unable to face further court action by survivors.

Sources confirm she was recently moved into palliative care at the nursing home.

"My only regret is she was never held totally to account for the misery she caused to the former cult children," said former Victoria police detective Lex de Man, who investigated the cult and its leader after the children were freed from the lake house. He eventually helped track her down in the Catskill Mountains in New York state and had her extradited back to Victoria in 1994.

On the eve of the release of a book and documentary about the Melbourne cult and its tentacles in the US, Britain and Hawaii, Mr de Man said: "I have no sympathy for the woman I consider the most evil person I ever met in my police career."

Anne Hamilton-Byrne and her third husband, Bill Byrne, an Englishman who has set up businesses in Traralgon, fled Australia after the Lake Eildon house was raided by police. They had property in Kent, near London, and the Catskills, and were eventually found there after Victoria Police's Operation Forest joined forces with the FBI.

However, because of extradition conditions, as well as complex legal and moral issues, they faced only minor fraud charges in Melbourne, leading to $5000 in fines. Police and prosecutors did not pursue potential charges of kidnapping, administering drugs and assault, after deciding the vulnerable former cult children should not face cross-examination by the couple's QC, John Winneke.

Dr Sarah Moore, who was one of the first children taken by Hamilton-Byrne from a hospital with faked adoption papers, died last year, aged 46. She had suffered long-term mental and physical problems, which she attributed to an abusive and isolated childhood in the cult. She, like many in the cult, was repeatedly dosed with LSD in an initiation when she turned 14.

The cult's co-founder, former University of Melbourne physicist and one-time Queen's College head Dr Raynor Johnson, still has a plaque commemorating his academic achievements at the university, despite attempts to have it removed. He died in 1987.

Hamilton-Byrne was born Evelyn Edwards in Sale in 1921. Her mother was mentally ill and her father itinerant. She taught yoga in Melbourne and Geelong and began the cult with Dr Johnson in 1962.

Sources say her estate could be worth as much as $10 million. She still owns property in Australia, including homes in the Dandenong Ranges near Melbourne. She also has property overseas. The cult's holding company, Life For All Creatures, is administered by a group of current cult members. The company is registered as a charity.