(CNN) Prosecutors in the Manhattan district attorney's office have prepared a criminal case against Paul Manafort in the event that he receives a presidential pardon, Bloomberg News reported Friday.

The district attorney's office, led by Cy Vance, has been investigating Manafort, President Donald Trump's former campaign chairman, since 2017 in connection with loans he received from two banks, and has been pursuing other cases against Trump-related figures since around that time, according to a person familiar with the matter.

In recent weeks, the district attorney's case has shown signs of advancement, with prosecutors having issued a subpoena for documents to Manafort's longtime accounting firm -- Kositzka, Wicks and Company -- a key player in the financial fraud case against Manafort for which he was convicted by a federal jury, according to a person familiar.

There has been much public speculation that Manafort might seek and receive a pardon, but there is no firm evidence that such a step is in the works. Prosecutors with the special counsel's office said during a recent hearing that Manafort may have been motivated by the prospect of a pardon when he lied during interviews. Andrew Weissman, one of the prosecutors, said that Manafort may have lied because he did not want "negative consequences in terms of the other motive that Mr. Manafort could have, which is to at least augment his chances for a pardon."

Though Trump said late last year that he hadn't discussed a potential pardon for Manafort, he also acknowledged that the possibility wasn't "off the table." Trump has significant leeway to issue pardons for federal crimes, but he can't do so for state cases.

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