One witness embodies entire Trump fraud case — and she's testifying for both sides: biographer
Donald Trump Jr., Donald Trump and Ivanka Trump (AFP)

Donald Trump and his three eldest children are all scheduled to testify for both the defense and the prosecution in the $250 million New York fraud trial, but one other switch-hitter witness could prove to be the key to the case.

Rosemary Vrablic, who once advised Trump and his son-in-law Jared Kushner as a private banker at Deutsche Bank AG, is expected to be called by both sides in the trial starting Monday, and Bloomberg columnist Tim O'Brien said her testimony should be highly intriguing.

"Trump was a slippery client, even for a bank that repeatedly found itself being investigated for a wide range of suspected violations such as money laundering, tax evasion, bribery, market manipulation and lax regulatory and compliance standards," O'Brien wrote.

Deutsche extended loans and sold debt for Trump during the late 1990s and 2000s in deals worth about $825 million to help jump-start its U.S. banking operations at a time when other lenders wouldn't touch the serial bankruptcy artist, and the bank stood by him after his casino company defaulted on $400 million in bonds and loaned him another $640 million for a Chicago development -- but he sued to avoid repaying after the 2008 financial crisis.

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The bank finally stopped doing business with Trump after that, but Vrablic stepped in to rescue Trump and signed off on $300 million in loans before he ran for president in 2016, so O'Brien said it will be important to show how she answers questions about whether she knowingly loaned him money despite his misleading statements.

"Whatever course the questioning takes, Vrablic can’t say yes in exactly the same way that both the prosecution and defense need her to say it," O'Brien wrote. "Yet each side has called her as a witness, suggesting that each is optimistic it will get the testimony it seeks. In that regard, Vrablic, who resigned from Deutsche three years ago, is the embodiment of James’ entire case against Trump."