The website billed itself as a place where older men with money could meet young women interested in dating someone who could support them financially.

“Find your sugar baby,” the site exhorted its users.

This year, Paul Aronson, an 84-year-old from Manhattan, contacted a 17-year-old girl, Shaina Foster, through the site and took her out to dinner. On a second date, Ms. Foster brought along her twin sister, Shalaine.

For a few hours on Oct. 1, the evening looked as if it might turn into an old man’s fantasy. The three dined at an expensive restaurant in Midtown. Then Mr. Aronson invited the teenagers to have a drink with him at the four-story brick townhouse he owns on East 38th Street.

He bought a bottle of raspberry-flavored rum from a liquor store on the way, a defense lawyer said. But instead of receiving caresses or whispered flirtations, Mr. Aronson ended up tied to a coffee table for 20 hours.