A solicitor, a bank manager and a land registry official helped a criminal gang make millions of pounds by effectively stealing people's homes.
The trio were recruited by drug traffickers to fool developers into buying the properties at knock-down prices.
In an extraordinary conspiracy the gang identified homes that were neglected or abandoned, their owners dead, or in care.
Then they erected an official-looking board in the garden, with the name of a bogus security firm.
On it was a mobile phone number, inviting calls from anyone with an interest in the house.
If no-one called, they boarded it up, changed the locks and went ahead and sold the property.
They made at least £3.8m, but it may have been much more.
The three professionals and gang members are being sentenced after being convicted of fraud and money-laundering offences.
Surjeet Chana, a 64-year-old grandmother, worked in customer services at the Land Registry headquarters.
Police found £38,000 hidden in the loft of her home in South London.
Solicitor Charles Spiropoulos, 48, did the conveyancing and collected money from the illegal house sales.
Bank manager Indipaul Sra, 42, let the gang move their huge profits in and out of accounts without reporting it to money-laundering investigators.
At times conspirators removed £100,000 cash in holdalls from his branch of Barclays (LSE: BARC.L - news) in Purley, South London.
Det Ch Insp Jonathan Benton, of Scotland Yard's Economic and Specialist Crime Command, said: "They were targeting often old and vulnerable people and literally stealing their homes, as well as flooding London streets with dangerous drugs.
"And they corrupted three officials, whose roles were crucial in making the fraud work."
The gang sold at least seven homes - the cheapest around £200,000 - usually in quick sales to unsuspecting developers who later discovered they were not the real owners.
They began to launder their drugs money through their barbers shop in Whyteleafe, Surrey, but when profits soared they began the property scam.
The gang were originally investigated for drugs by Scotland Yard's elite Special Projects Team, but evidence of the house fraud soon emerged.
Sales was overheard boasting to one associate: "I am caning the life out of this. No house is safe with me about."
The trio are expected to be sentenced next week.