NEW YORK—Attorneys for two former Marsh Inc. executives previously found guilty in New York's bid-rigging case asked a state judge last week to throw out the convictions due to “prosecutorial misconduct.”

At a hearing Wednesday in New York County Supreme Court, attorneys for former Marsh managing directors William Gilman and Edward J. McNenney, said prosecutors “failed to produce or disclose multiple forms of exculpatory evidence” that “could have affected the verdict.”

Robert Cleary, partner with Proskauer Rose L.L.P. in New York, who represents Mr. Gilman, and Scott D. Devereaux, a partner with Cooley Godward Kronish L.L.P. in Palo Alto, Calif., who represents Mr. McNenney, argued their previously filed motion asking New York County Supreme Court Judge James A. Yates to vacate the judgment.

Messrs. Gilman and McNenney—who were the first former Marsh executives to face trial in the case—were convicted of violating state antitrust law but acquitted of 20 other counts of fraud and larceny. They were sentenced to 16 weekends in jail, but the sentences have been stayed pending appeal.

The 440 motion, however, was filed separately and is based on evidence that was disclosed in a later trial against three other Marsh executives, all of whom were acquitted, the attorneys said.

The attorneys charge the New York attorney general's office was in possession of this material during their trial and was obligated to produce it. In addition, withholding the material “prejudiced” Messrs. Gilman and McNenney's right to a fair trial, they said.

Among the nondisclosed material, the motion cites “hundreds of thousands” of documents produced by Liberty Mutual Group Inc. unit Liberty International Underwriters, prior statements made by cooperating witnesses to other state's attorneys general and a prior conviction of one of the prosecution's cooperating witnesses.

Assistant Attorney General Hannah Stith Long said the material in question “would not have created any reasonable possibility of acquittal” and asked the judge to deny the motion due to a “lack of materiality.”

A ruling in favor of the 440 motion could result in a retrial that would include the previously undisclosed material.

Last week, Judge Yates requested additional information from both parties. Another hearing date has not been set.