“Victims who come into contact with the police are not always recognized as such and therefore remain in the hands of those who are exploiting them. Others are arrested as offenders or illegal immigrants,” the British Inspectorate of Constabulary and Fire and Rescue Services found.

Analysts say that some of the most vulnerable people are those who depend on welfare benefits and lack family life and support. As a result, they are easily influenced by people who suddenly appear in their lives.

“People often get picked up when they are hanging around, either at hostels or soup kitchens,” said Anne Read, an anti-trafficking response coordinator for the Salvation Army, a charity that manages the government support system for adult victims. “And, of course, now there is the internet, which enables predators to enter people’s homes,” she added.

That is how the teenager met her captor more than a year ago, through a messaging app on her phone.

Her mother, who had just lost her job at a bakery, had cut off her weekly allowance of about $26. That caused the girl to spend less time with her friends and more time on the internet.

“I was broke, I couldn’t do nothing,” the girl, now 15, said in an interview with her caseworker by her side. “I got bored and started chatting to people on my phone, and that’s how I met him,” she said, referring to her captor, who has not been taken into custody and whose real name is unknown to investigators.

“He was really sweet when I met him,” she added with the slight stutter she developed in the months she was away. “He kept buying me phone credit, and told me he would look after me and teach me how to make money.”

The first day they arranged to meet, he took her to her favorite fish and chip restaurant and ordered the large family menu, just for the two of them.