(CNN) Prosecutors suspect Paul Manafort might be trying to secretly claw back about a million dollars he agreed to hand over to the government for his financial crimes — and he could be using the same type of shell company at the core of his legal problems to fake a loan.

A mysterious shell company named Woodlawn LLC — which formed in the middle of special cousel Robert Mueller's investigation into Manafort in August 2017 — claimed in court that it deserves $1 million from Manafort's forfeiture proceeding. The company says Manafort, who was Donald Trump's presidential campaign chairman, still owes that amount to pay back a 2017 mortgage loan.

In a court filing Saturday, the prosecutor said he could not tell if the Nevada-registered corporation's $1 million loan to Manafort was "a real or sham transaction."

The prosecutor says more evidence collection "is necessary because the United States lacks information to be able to discern whether Woodlawn is a person other than the defendant," the court filing said.

Manafort's spokesman declined to comment on the accusation Saturday.

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