News outlets cited court records in reporting that a grand jury handed down an indictment this month adding the charge against 23-year-old Dylan Levesque.
The panel also indicted him on an aggravated child abuse and neglect charge originally filed by police in July.
Smyrna Police Chief Kevin Arnold has said Daylin Palmer was found unresponsive in a car at a home. He says officers tried to revive the boy but were unsuccessful.
The autopsy ruled the child’s death was due to a high body temperature and accidental.
Court records don’t list an attorney for Levesque.