Since the investigation went public in October 2004, a total of 16 individuals working at four insurers and Marsh have entered pleas. In addition to Mr. Bott at Liberty, seven were employed at Marsh, four at American International Group, three at Zurich American Insurance Company and one at ACE Ltd.

Mr. Bott, an assistant vice president with the Liberty Mutual subsidiary in New York, worked in the Excess Casualty Division. He pleaded guilty before Criminal Court Judge James Yates to attempted combination in restraint of trade and competition.

The charge carries up to a year in prison but is expected to be dropped in exchange for Mr. Bott's cooperation and testimony.

According to the complaint that was filed against him, Mr. Bott, while working at Liberty from 2001 to September 2004, was his company's primary underwriter dealing with Marsh. Brokers at Marsh, it was alleged, instructed Mr. Bott to "submit quotes on business where Marsh had predetermined which insurance carrier would win the bid."

According to the complaint filed by Confidential Investigator Robin Womack of the attorney general's office, Mr. Bott said he "understood that such quotes were intended to allow Marsh to control the bidding process" and designed to let the carrier who had the business keep their customer.

To do this he could either bid a higher price than the insurer who had the business or provide less attractive terms for the commercial insurance program, the complaint stated.

Marsh brokers, the complaint said, often gave Mr. Bott the amount bid by the carrier who held the business, a specific target or a range within which to bid so he could ensure his proposal was less favorable. He complied "on many occasions," according to the complaint.

"We are enormously disappointed by this development. To our knowledge no other Liberty employee is under investigation," said a Liberty Mutual representative, John Cusalito. He said Liberty was first subpoenaed in October of last year.