Prosecutors believe former Trump campaign chairman Paul Manafort made $60 million doing consulting work in Ukraine — a “significant percentage” of which he allegedly did not report on his tax returns — according a Monday court filing by special counsel Robert Mueller.

The filing was opposing the move by Manafort’s attorneys to exclude from trial a wide swath of evidence related to his Ukraine work, which began around 2005 and started to die down in 2014. The Virginia trial starts on Tuesday.

Manafort has been charged with bank fraud and tax fraud. Prosecutors argue that the ouster of his top Ukrainian client, ex-President Victor Yanukovch, from the country in 2014 led to a significant drop in Manafort’s income, and that “is relevant to the bank frauds that he later committed.”

The prosecutors argued in Monday’s filing that Manafort’s attorney had not followed U.S. District Judge T.S. Ellis’ directions in seeking to exclude the evidence. The prosecutors said the evidence was need to prove the extent of the work Manafort performed to earn the allegedly unreported income, and to show in particular the oligarchs who allegedly paid Manafort through foreign accounts. Among the charges Manafort is facing is failure to register foreign bank accounts with the government.

Prosecutors pointed to documents that Manafort is seeking to throw out that show his relationship with the oligarchs, including Sergei Lyovochkin, Andriy Klyuyev, Borys Kolesnikov and Rinat Akhmetov, according to the Mueller filing.

Manafort has pleaded not guilty.