ANDERSON, Ind. -- A coroner confirmed Friday that a boy didn't die in a house fire as initially believed, and the Madison County prosecutor says the blaze may have been set to cover the death's real cause.

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Prosecutor: Fire Probably Set To Cover Boy's Death

An autopsy and toxicology tests showed Mark Adrian Norris II (pictured, left) died of pneumonia before a fire burned his Elwood home Jan. 21, Madison County Coroner Marian Dunnichay said at a press conference.

The body of the child, who had cerebral palsy and used a wheelchair, showed signs of malnourishmenta and extensive muscle deterioration, and had multiple bedsores, Dunnichay said.

Authorities said they believe the fire at the boy's single-story house (pictured, below) was intentionally set. Madison County Prosecutor Rodney Cummings said Mark's mother, Jennifer Norris, was under suspicion.

"The child died, and at some point -- probably a day or two before the fire was set -- the mother discovered her child had died, and the fire occurred as a mechanism to cover up the death -- that's what I suspect probably happened," Cummings said.

Jennifer Norris, along with Mark's 1-year-old sister and 5-year-old brother, escaped unharmed from the fire. Mark was pronounced dead at the scene, and authorities initially thought the fire was to blame.

But Dunnichay said tests later "showed the absence of soot particles in the airways and a negative carbon monoxide level, which indicates that Mark Adrian Norris II was dead before the house fire."

Cummings said he is considering charges to file in the case. He said neglect and reckless homicide charges against Jennifer Norris were possible.

Jennifer Norris' grandfather, Cliff Payne, told RTV6 by telephone that he doesn't believe she was behind the fire.

"I'm upset over the whole deal. I don't think my granddaughter did anything wrong," Payne said. "They are saying the fire was intentionally set evidently, but I don't believe it."