A conman who cashed in a fake National Lottery ticket to claim a £2.5m jackpot has been jailed for nine years.
Edward Putman, 54, claimed he had found the winning ticket under a seat in his van in 2009 just before the deadline to claim the win passed.
But St Albans Crown Court heard he was helped by Camelot insider Giles Knibbs who knew how to cheat the system.
Putman, of Kings Langley in Hertfordshire, was found guilty of fraud by false representation.
The court heard the fraud came to light after Mr Knibbs, who had a row with Putman over how the winnings were divided, took his own life in October 2015.
Sentencing Putman, Judge Philip Grey called it a "sophisticated, carefully planned, and diligently operated fraud".
"You would have got away with this but quite plainly you were greedy", he added.
"This crime struck at the integrity of the National Lottery. You have also undermined the public's trust in the lottery itself."
Putman claimed the win on 28 August 2009 by using a badly-damaged ticket forged by Mr Knibbs, who worked for Camelot in the fraud detection department.
Mr Knibbs had seen a document containing details of big wins which had not yet been claimed and prosecutor James Keeley said there was "some trial and error" in producing the successful forgery.
The court heard each ticket had one of the 100 different possible unique codes at the bottom and Putman had gone to 29 different shops, providing a different ticket in each, before the right number was found at a shop in High Wycombe, Buckinghamshire.
Mr Knibbs confessed to friends he had "conned" the Lottery after the row with Putman, a convicted rapist and benefits cheat, in June 2015.
He also told them about technical inaccuracies in the creation of the ticket that Putman, of Station Road, had used.
Evidence suggested Mr Knibbs was initially paid £280,000 by Putman for his part in the ruse, followed by much smaller increments totalling £50,000.
Putman was paid the jackpot by Camelot in September 2009 despite the bottom part of the mangled slip missing the barcode, the trial heard.
Three years later he was sentenced to nine months in jail for benefit fraud after claiming £13,000 in housing and income support following his win.
In 2016, the Gambling Commission fined Camelot £3m for breaching its operating licence regarding controlling databases, investigating prize claims, and paying out prizes.
A Camelot spokeswoman said there were "some weaknesses in some of the specific controls relevant to this incident at the time and we're very sorry for that".
"We've strengthened our processes significantly since then and are completely confident that an incident of this nature could not happen today," she added.
The genuine winning ticket, which was bought in Worcester, has never been discovered.
Tapashi Nadarajah, from the Crown Prosecution Service, said Putman's "lies unravelled with the tragic death of his co-conspirator who he wasn't prepared to share the money with".