The Manhattan District Attorney’s Office has retained forensic accounting specialists to aid its criminal investigation of President Trump and his business operations, as prosecutors ramp up their scrutiny of his company’s real estate transactions, according to people familiar with the matter.

District Attorney Cyrus R. Vance Jr. opened the investigation in 2018 to examine alleged hush-money payments made to two women who, during Trump’s first presidential campaign, claimed to have had affairs with him years earlier. The probe has since expanded, and now includes the Trump Organization’s activities more broadly, said the people familiar with the matter.

Vance has contracted with FTI Consulting to look for anomalies among a variety of property deals, and to advise the district attorney on whether the president’s company manipulated the value of certain assets to obtain favorable interest rates and tax breaks, according to a person with knowledge of the investigation who, like others, spoke on the condition of anonymity because the matter remains highly sensitive. The probe is believed to encompass transactions spanning several years.