A man and his former wife, who prosecutors say were involved in several arson fires at their homes to defraud insurers, were accused in a federal indictment Monday of intentionally setting a blaze in suburban St. Louis that killed their 15-year-old son.

Steven Henry Kemper, 53, and Sandra Kay Bryant, 55, face charges of aiding and abetting the use of fire to commit mail fraud. Bryant is also charged with using fire to commit mail fraud. Both could receive up to life in prison if convicted.

Neither Kemper nor Bryant had a listed phone number, and the indictment did not list attorneys for them. It wasn't immediately clear if they were jailed.

Prosecutors allege that the two were involved in several schemes to defraud insurance companies from 1996 through 2002. That fraud, U.S. Attorney Richard Callahan said, included three arson fires at homes where the family lived — in 1997, 1999 and the 2001 fire in Florissant that killed their son, Zach.

The indictment alleges that the fire started early on Nov. 16, 2001, with hairspray used to ignite the fire in a utility room trash can. It contends the couple knew their son was asleep in a basement bedroom when the fire began.

Bryant, Kemper and two other adults got out, but Zach Kemper was found dead by rescuers next to a bed in the basement, just feet from a fire extinguisher.

St. Louis County prosecutors charged Bryant with arson and first-degree murder in 2002, but a judge declared a mistrial after ruling that he had mistakenly allowed jurors to hear evidence of a polygraph test. The Missouri Supreme Court ruled in 2006 that because the mistrial was declared over the defense's objection, state prosecutors could not retry Bryant because doing so would violate the U.S. Constitution's "double jeopardy" provision.

Callahan said agents with the U.S. Bureau of Alcohol, Tobacco and Firearms never gave up on the case.

"Early this year there started to be some major progress in the investigation," Callahan said. He declined to speculate if federal murder charges were possible.

Kemper has not previously been charged with a crime related to the fire or his son's death.

The indictment alleges that "substantial" homeowners and life insurance payments were made to the couple after the Florissant fire amounting to well over $200,000.