Jerry del Missier, a top Barclays executive at the centre of the Libor-fixing storm who quit the bank this week, was accused by a judge of giving misleading testimony in a major court case just last year.
In a ruling against the bank in September 2011, Justice Frank Newbould of the Ontario Superior Court in Canada, said Barclays had withheld the truth from a trading partner in order to protect its own profits. The judge told the court that he "had some difficulty in accepting [Mr del Missier's] evidence as reliable".
Mr del Missier resigned on Tuesday, along with Barclays chief executive Bob Diamond.
The case last year saw the Devonshire Trust accuse Barclays of misrepresentation and breach of faith. It believed that Barclays had not been forthright about the state of the financial markets as the credit crunch began in 2007.
Barclays did not want Devonshire to close off profitable lines of business in the asset-backed commercial paper market, and so offered a falsely optimistic view of economic conditions, claimed the lawsuit.
The judge wrote in his ruling against Barclays: "If Mr del Missier held the rosy view that he testified to, of which I have considerable doubt, it appears that it would have been a misinformed view."
Barclays had failed to "be honest and candid" with Devonshire, went the ruling. Barclays declined to comment on this court case or Mr del Missier's testimony.
The bank was fined £290m last week for manipulating the interbank lending rate, known as Libor.
It is understood that it was Mr del Missier who misinterpreted a conversation with Mr Diamond after he came off a call in October 2008 with Paul Tucker, the deputy governor of the Bank of England.
Due to that misinterpretation, Mr del Missier told staff that they had been instructed by the Bank to deliberately lie about their Libor submissions.
The FSA said: "As the substance of the telephone conversation was relayed down the chain of command at Barclays, a misunderstanding or miscommunication occurred.
Mr del Missier said: "My 15 years at Barclays have been a time of great accomplishment, both for me personally and for the bank. I am grateful for the opportunities that were provided to me and proud of what we achieved."