PENSACOLA, Fla. — The former chief executive of a defense contractor with ties to U.S. Rep. John Murtha pleaded guilty in federal court Tuesday to a kickback scheme and defrauding the Air Force, and promised to cooperate in an ongoing criminal investigation.

Federal prosecutors said Richard S. Ianieri solicited kickbacks from a subcontractor in Pennsylvania while he headed Coherent Systems International. Ianieri also was charged with filing false purchase orders related to an Air Force contract in Florida.

Ianieri pleaded guilty to both charges during a hearing in Pensacola, Fla., and is scheduled to be sentenced in September. He could face up to 15 years in prison.

A nine-page plea agreement Ianieri signed says the government will urge a lighter prison sentence if he provides substantial assistance "in the investigation or prosecution of other persons who have committed offenses."

Last week, Murtha spokesman Matthew Mazonkey called the allegations in Ianieri's case "disturbing, and if true, then the individuals and companies in question should be held accountable under the law."

Murtha has directed hundreds of millions of dollars in government contracts over the years to Coherent and other defense contractors. His spokesman declined to comment Tuesday on Ianieri's plea.

Executives at Coherent and two other companies named in court papers in Ianieri's Florida case have donated more than $95,000 to Murtha's re-election campaigns and his political action committee since 2002, according to Federal Election Commission records.

One of the companies is Kuchera Industries of Windber, Pa., about 10 miles from Murtha's political home base of Johnstown.