Weisselberg’s unique position in the Trump Organization puts him among a small number of people who could provide prosecutors with crucial evidence of intent to commit fraud. Legal experts say Trump may try to put distance between himself and any controversial valuations of his properties and businesses by citing Weisselberg’s role as financial gatekeeper, as he did in the 2007 defamation case.

“It may very well be that Weisselberg will be Trump’s defense in a criminal case,” said Michael Bachner, a defense attorney who once worked as a prosecutor with Vance in the Manhattan office.

If Trump argues that he merely relied on the advice of his accountants and lawyers, Weisselberg could be in the position of having to take the heat himself for any potentially fraudulent dealings, Bachner said – unless the accountant makes a deal with prosecutors and implicates Trump.

“If I’m Trump, I’ve got to be nervous about this,” he said.