Former fugitive tycoon Asil Nadir is facing up to 14 years in jail as a political row erupted over his payments to the Tories.
But the Conservative Party rejected calls to repay £440,000 in donations from Nadir's Polly Peck business empire more than 20 years ago.
A statement read: "There is no evidence that money donated to the Conservative Party from the Polly Peck group was stolen."
The jury trying Nadir reached verdicts on the final counts he faced - after finding him guilty of three counts of theft on Monday.
In total, Nadir, 71, was convicted of 10 theft charges and will be sentenced at the Old Bailey tomorrow. He was remanded in custody.
The jury found that he plundered Polly Peck of £28.6 million between 1987 and 1990 - the equivalent of £61.8 million today. He was cleared of three offences relating to more than £5 million.
Nadir was one of the Tories' biggest benefactors in the Margaret Thatcher era. But Polly Peck, one of the most successful companies of its time, collapsed in 1990 owing £550 million.
Nadir was charged with theft but fled to the Turkish Republic of Northern Cyprus to avoid trial in May 1993. He returned voluntarily in 2010 vowing to clear his name. He blamed the Serious Fraud Office for orchestrating his downfall and said he fled because he was a broken man.
Prosecutors will ask the judge to impose a sentence in double figures to take into account the large amount stolen and Nadir's 17 years on the run.
Each charge carries a maximum sentence of seven years but the judge could make some sentences consecutive when considering an overall figure.