A fraudster, named "Fizzy" because of his love for champagne, has been jailed for conning people out of their life savings with a bogus lottery scam.
Frank Onyeachonam, 38, of Canning Town, east London, ran the UK-end of a global scam that was orchestrated from his native Nigeria.
The Old Bailey heard how he extracted up to £600,000 from pensioners to fund a luxurious lifestyle.
He was jailed for eight years for charges of conspiracy to defraud.
The court heard how he deliberately targeted pensioners because they were potentially vulnerable.
The scam - known as an "advance fee" fraud - saw Onyeachonam send victims emails claiming they had won millions of pounds on a non-existent Australian lottery. He asked them to send him money so he could release their winnings.
Afterwards, the victims would then become hooked on the scam and made extra payments, which forced several victims to come out of retirement in order to pay back high-interest loans they had taken out to pay him.
Fourteen victims, mainly from the US but one from Britain, were found to have lost a total of about £900,000.
Emails showed victims pleaded with Onyeachonam to send them money to pay for healthcare, while some died before he could be brought to justice.
Some of those exploited by Onyeachonam were also investigated themselves after they were used as "pawns" to launder the proceeds of the fraud by sending on money from other victims or setting up business accounts.
When his luxury flat in Canary Wharf was raided, police discovered an "Aladdin's cave" of evidence, which included notebooks containing the names, addresses and cash tallies relating to 406 people.
If all of those in the notebooks suffered losses, the fraud is likely to have run to at least £5m and possibly as high as £30m.
Co-defendants Lawrencia Emenyonu, 38, and Bernard Armah, 51, both of Wood Green, north London, were found guilty of money laundering, and were jailed for 18 months and eight months respectively.
Onyeachonam was seen as the key figure in the UK but police suspect a criminal network was in place in several countries around the world.
Authorities found an alleged co-conspirator abroad had an email containing the details of more than 100,000 potential victims.
The alleged mastermind or "chairman" of the network is based in Lagos in Nigeria, and is currently under investigation by authorities there.