Her interview with the program has prompted US authorities to launch a criminal investigation, and in late December agents flew the teenager to the United States for a full interview after Channel 4 News alerted authorities.  The Department of Homeland Security in Washington DC says the girl, known only as Maria, had "significant information" and possessed a "remarkable memory" of her experiences inside the gang.

Since the 1990s thousands of women have disappeared from Juarez, and hundreds of bodies bearing signs of rape and sexual mutilation were dumped on waste ground in the city.  Thousands more have never been found. 

Despite international coverage of the story, including a film starring Jennifer Lopez, the disappearances continue.  In 2009, 55 teenage girls vanished in the town, which has been gripped by violence as two drug cartels fight a lethal turf war for cocaine smuggling routes to America.

While investigating the fate of the missing girls, Channel 4 News correspondent Nick Martin and producer Guillermo Galdos discovered Maria and carried out the interview while she was in hiding.  Few girls return after going missing, and Maria's interview sheds light on the fate of so many in her position.

She said she had been given presents and promised a job in an office by the gang member but was instead drugged and raped and sold to men.  She explained what the gang did to one girl who tried to escape.

"They took a gallon of gasoline and started pouring it over her," said Maria.

"One of the men told me 'if you don't do as I say, I will do the same to you'. I wanted to look away - but they didn't let me."

"Even though the girl was on fire, they kept hitting her.  They were laughing as if they were enjoying what they were doing.  They burnt her alive."

Maria, which is not her real name, said the gang held young women in a house on the Mexican border until they were sold to the US as sex slaves.  But she said they also dealt in children and told of one occasion when the gang was contacted by a woman in New York.

"She called and was very angry.  She said she needed a seven-year-old girl and a nine-year-old boy, and she needed them in three days."

Maria told Special Agents that the gang would prowl the streets of poor areas and look for children.

 "They stole the children," she said.  "One of the gang members took a six-year-old kid.  I had to look after him for three hours.  He told me he wanted to see his mummy."

"Then I started crying.  I said, 'I don't think you're ever going to see your mummy again.'  All he kept saying was 'I want to see my mummy.'"

US officials have a keen interest in this case.  As a result of the interview US officials have begun investigating along with the Mexican authorities.

Maria, who managed to escape after a gang member left her alone in a house, says children were often around, but not for long.

"I saw the Americans taking kids," she said.  "A four-year-old and another boy, he barely walked, he was only about two years old.  They took them to New York."

The US State Department estimates that more than 20,000 young women and children are trafficked across the border from Mexico each year.  But conviction rates remain low.

Mexico's Attorney General Arturo Chavez has been accused of not doing enough to bring human traffickers to justice but insisted it was an issue the country was "definitely focusing on."

Maria has been told that she could have to give evidence against the gang if they are caught.  It is something she says she is determined to do.

"Women are sold.  They are abducted, bought and even killed by these men. If these men are ever found, jail won't be enough to make them pay for the way they've made us feel."