Man accused of killing mother and grandfather dies awaiting trial

Autopsy determines death of Nathan Carman, awaiting trial for killing his mother, was not suspicious
Carman was found dead in his jail cell at a New Hampshire correctional facility
The U.S. Marshals Service will not release the 29-year-old's cause of death at his family's request
Carman pleaded not guilty to fraud and first-degree murder charges in connection with his mother's death at sea
Carman was also accused of killing his grandfather, though he was never charged for that crime