The death of a woman found in the back of a police vehicle in Hadong, South Gyeongsang Province, on Saturday was likely due to heatstroke from being in the hot car for up to 36 hours, police said Tuesday.

The Hadong Police Station unveiled initial autopsy results from the National Forensic Service that suggested a high likelihood that the woman’s death was related to hyperthermia -- a life-threatening condition caused by an excessively high body temperature.

The woman in her 40s was found dead 36 hours after she entered the vehicle for unknown reasons. Surveillance footage shows the victim entering the unlocked vehicle in the police station's parking lot through a rear door at around 2 a.m. Friday.

She was trapped for 36 hours amid blistering heat until she was discovered at around 2 p.m. on Saturday by a police officer. The backseat doors of police vehicles cannot be opened from the inside to prevent suspects from escaping, and the front seats were separated from the back by a partition.

The region has been under a heat wave warning at the alert level since July 23, with daily temperatures reaching a high of 34 degrees Celsius on Friday and Saturday.

Police are conducting further investigations to determine why the woman had entered the car and whether local police officials violated any regulations concerning police vehicles.

The final autopsy results are expected to be released within a month.