Detective Inspector Kevin Hyland speaks to the press outside New Scotland Yard in London on Friday. (ANDY RAIN/EUROPEAN PRESSPHOTO AGENCY)

Three women held against their will in a south London house for more than 30 years had been brainwashed, restrained less by force than by “invisible handcuffs,” British police said Friday.

The case has been described in the news media as Britain’s worst case of “modern-day slavery” and likened to that of Ariel Castro, the man who kidnapped and tormented three women for years in Cleveland.

A 69-year-old Malaysian woman, a 57-year-old Irish woman and a 30-year-old British woman were rescued from a house in Lambeth, a borough in south London, last month after reaching out to a charity.

Details of the case emerged Thursday when a man and a woman, both 67, were arrested on suspicion of forced labor, domestic servitude and immigration offenses. They were released on bail early Friday after surrendering their passports.

Police told reporters Friday that the suspects, who are not British, had been arrested before, in the 1970s, but did not give further details.

Although the specific conditions of the women’s captivity remain vague, police have said they think they were beaten but not sexually abused.

Cmdr. Steve Rodhouse of London’s Metropolitan Police said that to outsiders, the five may have appeared to be a “normal family” and that police were trying to understand “the invisible handcuffs that were used to exert such a degree of control” over the women.

“What we have uncovered so far is a complicated and disturbing picture of emotional control over many years, brainwashing would be the most simplest term, yet that belittles the years of emotional abuse these victims have had to endure,” he said in a statement.

Police said that they did not think that the women were trafficked or that there were other victims.

The women are “very distressed” and are “making as much progress as we can expect them to,” Aneeta Prem, founder of Freedom Charity, told the BBC.

Prem said that after watching a series of BBC documentaries featuring her organization, which raises awareness of forced marriages and related violence in Britain, the Irish woman contacted Freedom Charity on Oct. 18.

“Sensitive negotiations” followed about how to manage their escape, Prem said. “It was a drip-by-drip process of her revealing information. She just had one point of contact within the charity. It was prearranged when she would call and how it was done.”

She added that calls were made “in a very secret way.”

“It wasn’t that the people in the house knew she had that phone,” Prem said.

It was unclear whether the 30-year-old British woman was born in the house, but Prem said the woman had spent “all her life in captivity.” This is the first time, Prem said, that the woman has been able “to use a phone and experience some basic things in life that all of us take for granted.”

On Oct. 25, the Irish woman and the British woman agreed to meet with the charity and police officers, walking out of the house when their captors were not there.

The women then directed police to the house, where they rescued the Malaysian woman.

“All three were taken to a place of safety that same day, they are all highly traumatised and remain in the care of professionals,” the Metropolitan Police said in a statement Thursday.

Commenting on the women’s first moments of liberty, Prem said: “They threw their arms around me and thanked me for the work that Freedom had done.” When her staff had learned of the escape, “the whole call center erupted in cheers and there were tears, and everyone was incredibly emotional.”

The Metropolitan Police said it had “never unearthed such a staggering example of people held against their will for their whole lifetime.”