Officers checked the vehicle and called Houston Fire Department paramedics. Dong was pronounced dead at the scene.
Police say Dong left a lengthy note stating that she believed she was being poisoned and that she had placed the poison in a container in the trunk of her vehicle.
HazMat team members were called as a precaution. A thorough examination of the car was conducted, but no signs of a hazardous chemical were found in or near the car.