But a report in the Mail On Sunday claims a farmer was convinced to lie during the investigation and claim he sold wild boar to the Furys.
UKAD have since confirmed they will investigate and if the Furys are found guilty of tampering with the initial investigation it could mean an eight-year ban for a second offence.
Lancashire-based farmer Martin Carefoot alleges he was offered £25,000 by a friend of the cousins to lie but was never paid.
“I just went along with it, and they always dangled this carrot that I was going to get paid,” he told the Mail on Sunday.
“When things got quite serious, they offered me a sum of money before it went to court in London, and a sum of money after. I went along with them because, I suppose, in my own way I was just helping them out.”