Hundreds of Londoners are still falling victim to an elaborate rental scam which is costing the economy billions every year, writes BBC London's Marc Ashdown.
Conmen advertise property for rent in exclusive areas of the capital - then trick would-be tenants into sending advance payments via money transfer agencies like Western Union.
Since BBC London first revealed the plot in 2008, dozens of people each month have contacted us to report similar scams operating using property advertising sites.
Friends Pauline and Sina have both recently moved to London from Germany. They met on a social networking site and soon found that both had fallen for the same scam. They had seen flats for rent on the website Gumtree and contacted the landlord by email.
After lengthy exchanges, they were asked to prove they could afford the flat by transferring money to a trusted friend using Western Union. All the landlord needed was a copy of the receipt, and the flat was theirs.
But in truth, this is all the information he needed to intercept their money and vanish from trace. Between them they lost over £2,000. The conman, who used the name Michael Jelbart, did leave one scrap of evidence. A scan of his passport - sent to convince them he was genuine.
We tracked him down, but in fact the real Michael Jelbart is just another innocent victim of the same scam. He lost £1,000 but also sent the scammers his passport to prove his identity, unaware it would be used in future cons.
Gumtree say they remove the fake adverts as soon as they appear, and have very clear details about potential scams and how to report them.
Gumtree say they remove fake ads as soon as they appear
We also put it to Western Union that it is too easy for these conmen to intercept money using their service. They maintained security is important to them, and no money should be cashed until five items of information are presented.
A valid identification, unique reference number, where the money was sent from, where it is being sent to, and the approximate amount.
A spokesman urged customers never to share any of these details with a third party. They did admit the company has problems with some corrupt agents, but insisted every step is taken to ensure every transaction is carried out securely.
But these adverts continue to appear daily.
The newly established National Fraud Authority is encouraging would-be tenants to report anything suspicious they see in cyberspace. The agency will be co-ordinating efforts to crackdown on these fraudsters by gathering intelligence on every case.
Senior officials told BBC London this kind of fraud is costing the UK economy around £30 billion every year.
In 2008, we tracked one fraudster to Lagos, in Nigeria, where we contacted them by phone. Unfortunately, the West African man we spoke to was at first unsure of what flat we were discussing, didn't know what his name was, and claimed to be in Paris. When asked if he meant Lagos, he put the phone down.
Once intercepted, the chances of a victim of this fraud getting their money back appear slim. Local police in the cases we have investigated will look into each case, but if the money has been taken in another country it is difficult to pursue.
The new fraud authority hopes to improve the situation. But the first line of defence remains the vigilance of the individual internet user.
If you see anything which looks 'too good to be true' report it now.
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