The crucial next phase in the Manhattan inquiry will begin this week when investigators collect a vast trove of digital records from a law firm that represents Mazars, according to people with knowledge of the matter, who spoke on the condition of anonymity because of the sensitive nature of the investigation, as well as former prosecutors and others who described the next steps.
Armed with the subpoena, the investigators will go to the law firm’s Westchester County office outside New York City and take away copies of tax returns, financial statements and other records and communications relating to Mr. Trump’s taxes and those of his businesses.
The inquiry, which began in 2018, initially examined hush-money payments to two women who had said they had affairs with Mr. Trump, relationships the former president has denied. But it has since grown to include potential crimes like insurance, tax and banking fraud.
Even before the Supreme Court ruling, Mr. Vance’s investigation had heated up, with his office issuing more than a dozen subpoenas in recent months and interviewing witnesses, including employees of Deutsche Bank, one of Mr. Trump’s top lenders.
One focus of Mr. Vance’s inquiry is whether Mr. Trump’s company, the Trump Organization, inflated the value of some of his signature properties to obtain the best possible loans, while lowballing the values to reduce property taxes, people with knowledge of the matter have said. The prosecutors are also examining the Trump Organization’s statements to insurance companies about the value of various assets.
The records from Mazars — including the tax returns, the business records on which they are based and communications between the Trump Organization and its accountants — may allow investigators to see a fuller picture of potential discrepancies between what the company told its lenders and told tax authorities, the people said.
It remains unclear whether the prosecutors will ultimately file charges against Mr. Trump, the company, or any of its executives, including Mr. Trump’s two adult sons, Donald Trump Jr. and Eric Trump.