Tax and financial records that former President Donald J. Trump fought to keep secret for nearly 18 months have been turned over to the Manhattan district attorney’s office, which is investigating possible fraud by Mr. Trump and his company, an official said.
The voluminous records, including eight years of personal tax returns, were handed over to prosecutors on Monday, the same day that the Supreme Court rejected Mr. Trump’s final bid to block a subpoena for them.
A spokesman for the district attorney, Cyrus R. Vance Jr., confirmed in an email that the office had received the records just hours after the court issued its brief, unsigned order.
Mr. Vance’s investigation, which started more than two years ago, has recently zeroed in on possible tax and bank-related fraud. Investigators are particularly concerned with whether the Trump Organization inflated or otherwise manipulated the value of its properties in order to obtain loans and tax benefits.
Mr. Trump has excoriated Mr. Vance and his investigators, saying that their work is just the latest example of a politically motivated campaign to charge him criminally. In a lengthy statement reacting to the Supreme Court decision, he again called the investigation a “fishing expedition” and a “witch hunt,” linking it to his other legal troubles, including a special prosecutor’s investigation into Russian interference in the 2016 election and his two impeachment trials. He vowed to “fight on.”
The work facing Mr. Vance’s office is daunting. Prosecutors have begun combing through millions of pages of esoteric financial documents, saved as digital files. In addition, an outside consulting firm brought on by Mr. Vance is scrutinizing commercial real estate and tax strategies. The office has also enlisted the help of a former federal prosecutor, Mark F. Pomerantz, who has significant experience with white collar and organized crime.
Public interest in the case remains at a fever pitch in New York City and other Democratic strongholds. It is a key issue in the campaign to succeed Mr. Vance as the Manhattan district attorney, though the eight candidates for the office, all Democrats, have for the most part refrained from commenting on the specifics of his inquiry.
Along with the investigation in Manhattan, Mr. Trump also faces a criminal inquiry from Fulton County prosecutors in Atlanta, who are looking into his attempts to persuade officials to manipulate the election results in Georgia.
Despite the appetite for prosecution among Democrats, experts say that the case against the former president will not be an easy one to make.
“In an office that’s handled many, many high profile cases over many decades, this would be the highest profile case ever,” said Daniel R. Alonso, who was Mr. Vance’s top deputy from 2010 to 2014 and is now in private practice. “We won’t know until we see the evidence how difficult it would be to win convictions, but cases like this one are never easy.”
The Supreme Court decision allowed Mr. Vance to obtain eight years’ worth of Mr. Trump’s tax returns. But it also granted his office access to the business records that underlie the information in those returns, which may contain important details and context that prosecutors would not find in the tax returns alone.
One focus of Mr. Vance’s inquiry is whether Mr. Trump’s company, the Trump Organization, falsely 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.
If Mr. Vance were to indict Mr. Trump — which is far from a sure thing — the result would be the potential criminal trial of a former U.S. president, a stunning event that would most likely keep Mr. Trump’s name in the news for months to come, although not on terms the former president would prefer.