Jason Andrew Copas, 30, is accused of leaving the girl in a hot car on a day when the outdoor temperatures reached more than 100 degrees.
Police said Copas went into an electronics store and spent more than an hour there. When he returned to the car he found Dezarea Marie Scott ill and drove her to a hospital.
That hospital quickly transferred her to Vanderbilt Children's Hospital where the child was diagnosed with heat stroke and hyperthermia. She died five days later.
Copas' remains in custody on a $500,000 bond.
Davidson County district attorney's office spokeswoman Susan Niland said it could be four to six months before the grand jury considers whether to indict Copas.
Child's death case goes to grand jury
An Old Hickory man could face a homicide charge for leaving his girlfriend's daughter in a hot car while he went into a store, police said.
Jason Andrew Copas, 30, remained in jail Monday after a preliminary hearing.
Authorities said he left the 18-month-old girl in the car for more than an hour while he went into a Hermitage electronics store on Aug. 22.
When he found the girl in medical distress, he drove her to a local hospital, police said. She died Aug. 27.
Copas was charged with aggravated child neglect. His case was sent to a grand jury Monday.