For decades, Steven Croman was a successful landlord in New York City. His companies bought up more than 140 Manhattan apartment buildings, often filled with rent-regulated tenants. And then, methodically, he pushed them to leave, buying them out of their leases for relatively modest sums or, if that did not work, harassing them until they left, tenants said. He was a regular on “worst landlords” lists. His tenants even started a website against him.

Mr. Croman’s business came to embody in many ways how rent regulations have eroded in the city, putting housing out of reach for more and more people. He was able to deregulate most of his rent-stabilized apartments within just a few years of buying the buildings, enabling him to collect much higher rents.

On Monday, though, his fortunes took a different turn. Mr. Croman, 49, turned himself in to the authorities around 7 a.m. in Lower Manhattan. He was charged with 20 felonies, including grand larceny, criminal tax fraud, falsifying business records and a scheme to defraud, relating to accusations he inflated his rental income to secure more than $45 million in bank loans. He faces up to 25 years in prison. His mortgage broker, Barry Swartz, 53, was charged with 15 felonies.

The New York State attorney general’s office, which investigated Mr. Croman for almost two years, also filed a lawsuit against Mr. Croman on Monday, seeking to force him to give up his real estate business and pay millions of dollars in restitution to tenants and penalties.