A CNN Documentary that tackles sex trafficking in the Philippines has led to the conviction of 54-year-old American Jeffrey Herschell.

Titled "The Fighters," filmed over the course of two years since 2011, the documentary featured three Filipino girls whose testimonies were used by authorities to convict Mr Herschell of child pornography.

Mr Herschell was sentenced to 12 years federal imprisonment on May 28 after the three girls bravely shared their harrowing experiences at the hands of sex traffickers, first to the CNN production crew and later to US investigating authorities.

"Whatever the American client wants us to do, we must do it," one of the girls told CNN during filming in 2011. The documentary was aired as a two part special on May 17 and 18 this year. (For full video of documentary, visit: http://www.youtube.com/watch?v=sQSISOY8FE8)

According to the girls, traffickers in Manila who worked behind the camera were charged by clients like Mr Herschell about $27 per hour to "direct" the live online streams. The camera man was paid to ensure that the girls followed the often tortuous, creepy orders.

In the documentary, the girls used the words "maniacs" to describe the Americans. "You need to stop victimizing girls like us," they added sharply.

They went on to share how men at the internet shop would order them to take off their clothes and then dance provocatively in front of the camera. "I was kind of embarrassed because I'm not used to being naked like that," one of them said.

The girls told CNN how they were pushed to do disturbing sexual fantasy acts with Westerners and how animals sometimes became part of the abuses that were streamed online. There were also freaky orders from clients that involved their urine being mixed with juice as a drink.

"That's what the American client wants. He demands anyone who feels like urinating should do so, but that he wants us to do it in front of the camera," one of the girls recounted.

These shocking details served as leads for the Homeland Security investigators in the U.S. to search Mr Herschell's house in Pennsylvania in 2011. The search yielded dozens of explicit videos and photos of children found in Mr Herschell's computers, cell phones and hard drives.

In January this year, Mr Herschell issued a guilty plea for coercing and enticing a minor, as well as for possession of child pornography materials. He was sentenced 12 year imprisonment on Tuesday, May 28.

One of the investigators told CNN that the information provided by the three girls in the documentary proved integral in the conviction of the American.

The probe on Mr Herschell's case involved U.S. agencies, the Philippines police authorities and the Visayan Forum Foundation, a non-profit organisation that fights modern day exploitation in the Philippines.

At present, there are about 100,000 children engaged in illegal sex trade in the Philippines, according to UNICEF. These kids are often left suffering with severe trauma.

Visayan Forum Foundation director Cecilia Flores-Oebanda related to CNN how girls would often be awoken in the middle of the night, screaming and crying in fear that the traffickers would come to get them again. As part of the VFF, Oebanda is in charge of caring for rescued victims of child trafficking in her country.

"Sometimes one of the kids suddenly gets sick and vomits," she said. "Our psychologist said it's because she remembers what these guys on the Internet asked her to do."