After further investigation, authorities concluded that the deceased man, security guard Chitchai Phetchsimoung, 44, had killed the two victims before driving his vehicle into a head-on collision with a truck transporting liquid natural gas (LNG), resulting to his instant death at Bu Krasang Intersection. Chitchai reportedly had a history of mental illness.

The driver of the truck, Sommai Songpat, 46, who waited for police at the scene of the crash, told them that Chitchai’s speeding sedan had overtaken another 10-wheel truck by swerving into his lane. Sommai said he tried to avoid the oncoming car but was unable to do so.

Pol Captain Thewin Surasoon of the Thab Mai precinct subsequently visited Chitchai’s home to inform his family about the fatal crash and found the bodies of Chitchai’s wife, Samruay Chaisiri, 49, and her daughter from a previous marriage, Wassana Suksamran, 10, in a pool of blood in a bedroom. Police also found the suspected murder weapon, a 50-centimetre knife, and a bottle of pesticides and traces of vomit near the bodies.

Police said they suspected Chitchai had killed the Samruay and the child and then unsuccessfully tried to commit suicide by drinking the pesticide, adding that he might have then deliberately killed himself by crashing into the LNG truck.