"He was starting to creep me out."

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.

Prosecutors say the two girls bound him with zip ties, took $470 in cash from his wallet and went on a spending spree with his credit cards, buying makeup and clothes, while he lay helpless on his living room floor.

On Wednesday, the Foster sisters, looking more like high school students than hardened criminals, pleaded not guilty in State Supreme Court in Manhattan to charges of kidnapping, burglary, larceny and related crimes. Justice Michael J. Obus ordered them returned to jail without bail. Both face a minimum of 15 years in prison if convicted of the top charge. [...]

According to court documents, Shaina Foster told a detective she did not understand why Mr. Aronson had reported the crime. "He asked to do things I wasn't going to do. He is ugly, old and disgusting. I tied him up. I took his money and left. He was starting to creep me out."