By James Lynn
BBC News, Newcastle
He Yun Jin, Lin Xiu Ming, and Weng Mei Fang disappeared in 2005
In March 2005 three Chinese teenagers vanished from a hostel in Newcastle.
Weng Mei Fang, 15, and 16-year-olds Lin Xiu Ming and He Yun Jin had applied for asylum after arriving at the city's airport on fake Japanese passports.
They disappeared several days later and, though a 29-year-old Londoner was jailed for smuggling them into the UK, the girls were never seen again.
The high-profile case left authorities in no doubt - slavery was alive and kicking in the north-east of England.
Since then, more Chinese girls have arrived at the airport and some have vanished under similar circumstances - two in 2006 and three so far this year.
But - as the UK marks the 200th anniversary of the Parliamentary Act which led to the abolition of the slave trade - mystery continues to surround the human trafficking gangs sending these girls to the region.
Det Chf Insp Joan Atkin from Northumbria Police, said: "We make as many enquiries as possible to determine the route the children have taken to the UK in an effort to identify the facilitators and any crimes committed.
"The police rely considerably upon information supplied by the children, who can be reticent to give information to anyone in authority."
Because of this lack of trust officers sometimes have little to go on when a trafficked child runs away.
So the force is also targeting their likely destination - the sex industry.
The teenagers destroy their papers before arriving at Newcastle
Between January and July 2006, Northumbria Police participated in Operation Pentameter, a Home Office initiative aimed at rescuing sex workers being held against their will.
Nationwide, 84 trafficked women were rescued, 12 of whom were aged between 14 and 17.
Pentameter was successful, and similar operations are planned, but all agree that more needs to be done to stop children slipping through the grasp of UK authorities.
To help achieve this, several children's charities are working with Newcastle social services to identify trafficking at the earliest possible opportunity.
One warning sign is a teenage girl, flying alone, on a one-way ticket.
Paul Woodhead from Save the Children said: "The girls destroy their papers on the plane, so once they enter the airport they'll be detained by immigration officials.
"This seems to have become common practice in recent years, where Chinese gangs are involved.
Many trafficked children are forced into prostitution
"They tend to be in their mid to late-teens and are probably being sent into a life of prostitution, work gangs or even domestic labour."
Once a likely case is spotted, the race is on to build trust with the youngster, to prevent them running away.
It is arguably the most important stage in the fight against child trafficking, according to Bruce Grenfell, manager of Newcastle City Council's Unaccompanied Minors Team
He said: "The youngsters tend to be very scared of authority figures from their homeland, so we have to explain that we're not the police.
"We're very hands on. We help the young people set up home - shopping for utensils for the kitchen, things like that.
"We also try to introduce them to other young people with similar ethnic backgrounds, help them build up friendships and reassurances.
"That's the key to defeating the traffickers - making their victims realise they have an alternative."