But before long, the investigators learned that the money was being moved to pay for sex and that the transactions were being manipulated to conceal Mr. Spitzer’s connection to payments for meetings with prostitutes, the official said.

Then, with the assistance of a confidential informant, a young woman who had worked previously as a prostitute for the Emperor’s Club V.I.P., the escort service that Mr. Spitzer was believed to be using, the investigators were able to get a judge to approve wiretaps on the cellphones of some of those suspected of involvement in the escort service.

The wiretaps, along with the records of bank accounts held in the names of the shell companies, revealed a world of prostitutes catering to wealthy men. At the center was the Emperor’s Club, which arranged “dates” with more than 50 beautiful young women in New York, Paris, London, Miami and Washington.

But its finances moved through the shell companies  the QAT Consulting Group, QAT International and Protech Consulting  which held bank accounts into which clients wired their payments, according to court papers in the case.

One of the booking agents, a woman named Temeka Rachelle Lewis, 32, told a client that wiring his payments to QAT Consulting was safe because it would show up “like as a business transaction,” according to an affidavit filed in federal court the case.

But the transactions proved to be anything but safe for Mr. Spitzer, who, aides said on Monday, was weighing possible resignation.

Last week, Ms. Lewis was one of four people charged by federal prosecutors in Manhattan with operating the prostitution ring. Also arrested were Mark Brener, 62, who is accused of heading the operation; Cecil Suwal, 23, who is said to have managed it day to day; and Tanya Hollander, 36, who worked part time as a booker.