By Phil Kemp
BBC Radio 5 Live Report
Record numbers of illegal immigrants convicted of the most serious crimes were deported from the UK last year but many arrested for minor offences are released to offend again.
Wang is in his thirties and lives in London but he shouldn't be.
His application for asylum was refused when he came to the UK six years ago from the Fujian Province in China.
Now that he has paid off his debt to the man who smuggled him here, any money he makes from selling counterfeit DVDs gets sent home to China.
Police seizures of pirate DVDs often number tens of thousands
"At the very beginning I could make £1,500 to £2,000 a week. Now it's getting worse. I could only get around £1,000 a week."
He might still be young but Wang is already thinking about retiring on the profits of his illegal trading.
"My family used the money to build a good house. I just want to make as much as possible, then I don't have to do anything when I go back to China."
The Home Office says there are no official estimates for the number of Chinese people like Wang, who are living in the UK illegally.
But Sha, who also sells counterfeit DVDs, says there are many like her.
"There are many people selling DVDs and most of them have experience of being arrested. It's very rare to hear of anybody who hasn't been arrested yet."
Sha paid around £20,000 to be smuggled into the UK from China.
She has been here illegally for three years because her application for asylum was refused.
But she has not been deported and she says that is a familiar story amongst her friends, who are also breaking the law to earn money.
"Of the ones who were deported, there are a few dozen. But I know hundreds, maybe a few thousand are selling DVDs."
When the police arrest someone like Sha, who they suspect is in the UK illegally, they have to contact the Border and Immigration Agency for advice about what to do.
Jan Berry, the chairman of the Police Federation - which represents serving officers - says this often means they are set free.
"What I'm told happens more often than not is that they are told to release them from custody and to advise them to go to Croydon or one of the immigration centres in order that they be dealt with there."
"Rarely if ever do the Border and Immigration Agency now go to police stations to pick people up."
Jan Berry says it is frustrating for officers who are told to ask suspected illegal immigrants to make their own way to immigration centres because they know they will not go there.
"Not only don't you expect them to go into the system, you're also re-injecting them back into society where they can carry on committing crime."
Tony Smith, regional director for the Border and Immigration Agency says they are committed to the removal of foreign national criminals and last year they removed more than ever before.
"We have to prioritise those removals that are the most harmful and so where people are committing serious crimes then they're the ones who'll be deported first."
"But that doesn't mean to say that others will be slipping through the net."
But the 5 Live Report hasn't just heard about counterfeit DVD selling.
We have spoken to illegal immigrants getting involved in organised crime because of the light touch they have experienced when they have been caught for lesser offences.
Many cannabis farms in the UK are operated by Vietnamese gangs
Ming, also from China, has been in the UK illegally for three years and he used to make money from DVD selling before he was introduced to other ways of making money.
"Normally the people from Vietnam, their business is growing drugs. They told me growing drugs could make a lot of money."
"I used to fake credit cards.We hired people who took the fake cards to casinos and shopping centres, things like that. In casinos, fake credit cards work really well."
Ming told our researcher he was also involved in bank fraud but he's only been able to branch out in this way because he's been let off before.
"When I was selling DVDs, I was caught by the police a few times, but not now."
5 Live Report: Immigration Limboland is on Sun 13 Jan at 1930GMT or afterwards at the 5 Live Report website.