CALDWELL - A 24-year-old man has been charged with involuntary manslaughter in the death of a 5-month-old girl left in a car in Caldwell in May.

Caldwell police said Haven Robb Hackworth was arrested Monday night in Marsing with the assistance of the Owyhee County Sheriff's Office.

MORE: Parents mourn loss of baby left in a car

He's charged in the death of Kyrae Vineyard, who was left alone in a car for hours while her mother's boyfriend went to a Caldwell car dealership to pick up a new vehicle.

Kyrae's mother, Elisa Johnson, said her boyfriend told her he forgot about the infant. Johnson wasn't with her daughter at the time.

Paramedics and officers arrived to find the girl strapped into an infant seat in the car's backseat. She had no pulse, and was pronounced dead at a local hospital.

MORE: Baby girl left in Caldwell car died from overheating

Kyrae died of hyperthermia, a condition that occurs when a person's body temperature is elevated. The cause of death was determined after an autopsy and toxicology tests.

Hackworth made his first court appearance on Wednesday. A preliminary hearing is scheduled for 8:30 a.m. August 16.

Hackworth was booked into the Canyon County Jail, but he was no longer being held there Wednesday evening.