New York Attorney General Eliot Spitzer wrung out two more criminal convictions Tuesday in his investigation into kickbacks and bid-rigging in the insurance industry.

Two

Zurich American Insurance

employees pleaded guilty in New York criminal court to charges stemming from a bid-rigging scheme engineered by

Marsh & McLennan

(MMC) - Get Report

, the nation's biggest insurance brokerage. The employees each pleaded guilty to a misdemeanor charge.

The Zurich employees worked in the insurer's excess casualty division. Last month two executives from

American International Group

(AIG) - Get Report

and another from

Ace

(ACE)

pleaded guilty to similar charges.

"The investigation is proceeding carefully and methodically," Spitzer said. "Our goal is to determine the full extent of wrongdoing in the industry and its effect on consumers, to punish those involved in misconduct, and to implement appropriate corrective measures."