CASTLE ROCK, Colo. -- Two children found dead in a parked car in front of their grandparents' home in Castle Pines died of complications from overheating, the coroner ruled.

The Douglas County Sheriff's Department released the coroner's finding on Friday. Deputy Cocha Heyden said the coroner did not rule on whether the deaths were accidental.

Five-year-old Jasmine Mendieta and 2-year-old Nathan Mendieta were found Aug. 20 in their mother's car on Bramblewood Drive.

Deputies were called to investigate a report of missing children and within minutes of arriving at the home, deputies found the children in their mother's red Honda Civic, which was parked in front of their grandparents' home.

Jasmine was on the floor in the front passenger side and Nathan was on the floor in the back, according to the children's grandfather, Ken Vanherpen.

Heyden said there were no signs of force entry into the car. The engine was off and the automatic windows were rolled up.

Vanherpen and many others wonder how a 5-year-old girl couldn't get out of a car, if she had been accidentally locked inside.

Heyden declined to say whether the doors were locked but said deputies had no trouble getting inside.

Heyden declined to discuss details of the investigation. She had said earlier that the investigation would be in a "holding pattern" until the coroner can determine whether the deaths were accidental.

Neighbors said the mother, Stacey Mendieta, 28, had recently gotten a divorce and quit her job, but that the children's father had not been in the picture for months. Family members told 7NEWS that Mendieta was planning to leave the country to meet up with a man she had met online.