As recently as three years ago, police in NI could not detect any signs of human trafficking
Well-hidden but happening "right under our noses", human trafficking in Northern Ireland is quietly on the rise, according to police.
The seedy underground world of lucrative exploitation, terror and fear is cloaked in secrecy.
BBC News Online's Emily Thomas explores the invisible crime that is said to be happening all over Northern Ireland.
"Modern day slavery" and "an obscene criminal activity" is how human trafficking was described by Detective Chief Superintendent Roy McComb, addressing the Public Accounts Committee at Stormont in April.
Tortured, raped, intimidated and trapped, people who are trafficked can suffer untold misery after being lured to the UK with promises of a better life.
Human trafficking is the movement of people, within countries or across international borders so they can be forced to work against their will using violence, deception or coercion.
The crime centres on control: violence, drug addiction and confiscation of documents are used by traffickers to build fear and dependency in their victims.
Most trafficking for sexual exploitation affects women and girls, who on arrival in the UK are often forced to work with little or no payment as prostitutes.
And police say this is happening "day by day by day" in NI.
The world of trafficking is shadowy and furtive making it difficult to get hard data about the problem.
There are "significant gaps" in knowledge about trafficking showing a system of data collection in NI is "virtually non-existent", according to a report released in January by the Northern Ireland Human Rights Commission and the Equality Commission for Northern Ireland (NIHRC/ ECNI).
Border policing is difficult in NI, making trafficking easier.
Assistant Chief Constable Drew Harris said that although trafficking in NI is happening "right under our noses", it is not being reported.
He said: "It is happening under the watch of people who should be wise enough to see it.
"After we carry out operations and raid places, neighbours say that they wondered why lots of men were coming and going to and from the premises at all times of the night and day.
"The brothels are in rural areas as well as town centres and in apartment blocks. They are being set up in plain sight," he said.
In NI, a "chicken run" system has been identified by the UK Human Trafficking Centre where trafficked women are moved between brothels disorientating them, keeping them isolated so they cannot seek help and giving punters more choice.
"On the rise"
The problem of human trafficking into NI is relatively new, and as little as three years ago, police were unable to detect any signs of it.
When UK-wide anti-trafficking initiative, Operation Pentameter 2, was launched in 2007, Northern Ireland Office Minister Paul Goggins claimed there was "no clear evidence" of trafficking.
But preliminary results of the initiative released in 2008, revealed five victims of trafficking had been rescued in NI, and six people had been arrested for controlling prostitution and people smuggling.
Since then, police have recovered 20 individuals who they "suspect have been trafficked for the purposes of prostitution, domestic servitude or to work in some form of business," according to Assistant Chief Constable Drew Harris.
But for all this police work, there has yet to be a single successful prosecution for people trafficking in NI.
In August 2009 the first man in NI to be convicted of people trafficking had his conviction overturned.
Mark Russell from Dromore in County Down, was arrested as part of Pentameter 2, when he was picked up as part of a raid on a brothel.
He was said to have collected women off the ferry from Scotland and taken them to the brothel.
But his record was later cleared after a mistake made by the prosecution service was discovered, and it emerged that the prostitutes involved said they had been willing participants.
Another man and his partner escaped trafficking charges, earlier this year.
Thomas Carroll and former prostitute Shamiela Clark were arrested in Wales in December 2008, this time for running a highly lucrative prostitute ring on both sides of the Irish border.
Over 35 brothels, mostly in the Republic, were said to have used trafficked girls, some as young as 15, controlling them through fear and voodoo rituals.
Thomas Carroll was convicted for controlling prostitution and money laundering
The young women had travelled from south America and Africa believing they were to be hairdressers.
But charges of trafficking against the couple were not pursued after they agreed to plead guilty to charges of controlling prostitution and money laundering, in February 2010.
Speaking at Stormont in April, senior PSNI officers expressed frustration at this outcome.
ACC Harris said police were: "bitterly disappointed that he was not convicted for human-trafficking offences, although he received very heavy sanctions".
Patrick Corrigan, Northern Ireland Programme Director of Amnesty International, argues that "cracking down on the people traders is only one half of the answer", and says, "we also need to guarantee that victims of trafficking will be protected".
Since April 2009 Women's Aid Federation Northern Ireland and the Migrant Helpline have received government funding to provide support and services to victims of trafficking.
But Mr Corrigan says that while the new services "have improved matters, the infrastructure to assist and support trafficking victims is still in its infancy".
"There is no secure accommodation and support for victims of trafficking for forced labour here, and while the PSNI officers now receive training on trafficking, there is a lack of similar training for front-line practitioners across other sectors."
Protecting victims is not only a humanitarian issue: enabling them to cooperate with police is essential for obtaining evidence to convict traffickers.
Patricia Lyness from the Women's Aid Federation of Northern Ireland explains: "these women are frightened and it's not always easy for them to provide evidence".
On 1 April 2010 a new provision of the Policing and Crime Act came into force, creating a new criminal offence in NI of paying for the sexual services of a prostitute who is, or has been, subject to force.
But Dr. Tom Obokata, Assistant Director of Queen's University's Human Rights Centre, isn't convinced that prohibition will help: "The danger is that it can drive the activity underground further, making it difficult for law enforcement authorities to detect, prosecute and punish".
Dr Obokata says the "restrictive immigration policy" in NI and the UK contributes to the rise in trafficking: "Because people cannot enter legally," he said "they rely on traffickers who can arrange clandestine migration."
He added: "A more serious problem is that the demand for trafficked people in sex and other industries is very high".
NI's multiple borders present another problem and the flow of migrants from south of the border as well as from GB make policing difficult.
ACC Harris said: "Prostitution does not respect our border. It surges backwards and forwards, depending on the need and demand for the services of prostitutes".
Juliet Singer, Chief Executive Officer of anti-trafficking NGO STOP UK stresses the importance of vigilance at NI's airports and coastal ports: "The border problems mirror Europe: lack of security at crossing points, apathy, lack of awareness training of security staff as a whole".
However, Ms Lyness from the Women's Aid Federation of Northern Ireland is confident that progress is being made and the shady world of trafficking is becoming exposed.
"In Northern Ireland we're beginning to understand the problem now", she said.