The people said Manhattan prosecutors are examining loans Mr. Trump took out on his flagship Fifth Avenue building, Trump Tower; 40 Wall St., an art deco skyscraper in New York City’s Financial District; Trump International Hotel and Tower, a hotel and condominium building at Columbus Circle; and Trump Plaza, an apartment building on Manhattan’s East Side.

All of the loans under scrutiny were made to Mr. Trump by subsidiaries of Ladder Capital Corp. LADR 1.76% , a New York City-based real-estate investment trust, the people said. Since 2012, Ladder Capital has lent Mr. Trump more than $280 million for the four Manhattan buildings, according to property records…

While the focus of prosecutors’ interest in Mr. Trump’s properties and loans isn’t known, they could be looking for discrepancies between loan documents and financial information submitted elsewhere by Mr. Trump, such as that on tax returns or submitted to an insurance company, legal experts said. Writing false information on a loan application with the intention of getting financial benefits one isn’t entitled to can be a crime under New York law, according to legal experts.