PITTSBURGH - A man sentenced to three life terms after being convicted of setting a western Pennsylvania fire that killed three firefighters a decade and a half ago is seeking a new trial, contending that the fire wasn't arson and alleging that reward money may have tainted the testimony of witnesses.

Gregory Brown, 33, was convicted of second-degree murder, arson and insurance fraud in the fire on Valentine's Day in 1995.

Prosecutors said that Brown and his mother, Darlene Buckner, started the fire in the basement of their four-story home to collect $20,000 in insurance money for a down payment on a new home. Investigators said that Brown poured half a gallon of gasoline on some clothes and ignited them.

Firefighters Thomas Brooks, 42, Patricia Conroy, 43, and Marc Kolenda, 27, suffocated when their air tanks ran out as they tried to grope their way out of the rapidly burning home. Buckner was convicted of insurance fraud and placed on probation.

During Brown's 1997 trial, defense attorneys said that the government should have told jurors about reward money and said which witnesses, if any, were paid. In court documents, Allegheny County prosecutors said that the witnesses had come forward before the reward was posted.

The petition for a new trial, citing an investigation by the Innocence Institute, of Point Park University, in Pittsburgh, said that the witnesses were paid $5,000 and $10,000. The defense is also challenging the arson finding, saying that all possible causes were not considered.

Gerald Hurst, a fire investigator from Austin, Texas who has been involved in the case for several years on behalf of the defense, said he believes that the fire was sparked accidentally from natural gas. Hurst said that one firefighter reported seeing flames shooting horizontally in the basement, which would indicate a gas leak.

Mike Manko, a spokesman for the Allegheny County District Attorney's Office, said prosecutors will respond in court documents.