The cause of death for the 83-year-old man whose body was found in the back of an SUV stopped in Cayucos in August was ruled “natural,” the San Luis Obispo County Sheriff’s Office said Thursday.

Donald Eugene Cunningham, a transient from the Bakersfield area, died of a heart attack and coronary artery disease, an autopsy found. Autopsy results also listed “acute morphine toxicity” as a contributing factor but was not the underlying cause in Cunningham’s death.

Deputies discovered Cunningham’s body Aug. 15 in the back of a parked SUV also occupied by Darwin Keith Alaskari, 59, Sherrie Lynn Boggess, 50, both transients from Bakersfield, and their 13-year-old child. Deputies reported a strong odor coming from the vehicle at the time.