A Georgia foster mother has been charged with two counts each of second-degree murder and cruelty after twin 3-year-old girls were found dead in a car.

Claudette Foster was charged Oct. 14, about two weeks after the Sept. 29 deaths of Payton and Raelynn Keyes, Hinesville police said. The two girls were in the care of Foster when they were found unresponsive in the backseat of a car in Hinesville, about 40 miles southwest of Savannah.

Hinesville police said Foster was charged with murder in part because she was negligent when she was taking care of the twins, NBC affiliate WSAV in Savannah reported.

Police told the station the girls were missing for hours before they were found unresponsive in the car at the home of Foster's fiancé.

“It was determined that there was a lack of supervision for the children,” Det. Bryan Wolfe told WSAV. “It allowed them to enter the vehicle and pass away.”

Preliminary autopsy results indicated the children died from accidental heatstroke, police said.

Foster turned herself in to police on Oct. 14. She is currently being held at the Liberty County Jail awaiting her first court appearance, according to police and jail records. It was unclear if Foster has an attorney.