A senior executive at Marsh & McLennan Companies Inc., and two American International Group employees pleaded guilty to criminal charges in connection with an ongoing investigation of fraud and bid rigging in the insurance industry.

All three defendants admitted to participating in a scheme that allowed Marsh, the nation’s largest insurance broker, to protect incumbent insurance carriers when their business was up for renewal.

In a statement, AIG said: “The two plea agreements by AIG employees announced today involve the same broker relationship, similar conduct, and the same division of the same AIG subsidiary as the plea agreements entered into by two other AIG employees last October.”

With yesterday’s action, New York Attorney General Eliot Spitzer has now obtained nine guilty pleas from executives at four different companies. All three defendants are expected to testify in future cases, as are the six other insurance industry employees who entered criminal pleas, Spitzer said.

Previously, two executives at AIG, two from Zurich American, one from Marsh and one from ACE pled guilty to criminal charges.

(via Office of New York State Attorney General)