A Phaisali district policeman shot his wife dead before turning the gun on himself after crashing their truck into a tree, Nakhon Sawan police said.
The body of Pol Lt Sanya Pakham, 40, was found around 6am lying near a slightly damaged pickup truck on Phaholyothin Road in tambon Tha Nam Oy, said Pol Lt Col Pitsanu Raksachan, an investigator at Phayuha Khiri police station.
Inside the pickup truck, police found his wife, Srisulak, 42, Both had suffered fatal gunshots to the head. A 9mm handgun, three 9mm cartridges and one spent bullet were found in the area.
Sanya was a deputy chief investigator at Takho police station before being moved to the Tha Tako police station. His wife worked at the Government Saving Bank's Tha Tako branch, said police.
Witnesses said they saw the pickup truck heading to Phayuha Seha district, swerve and hit a tree. Soon after, they heard gunshots. Then they saw the man get out from the vehicle and shortly later he was found dead.
Police have ruled it a murder-suicide.
Investigators quoted relatives of the couple as saying Srisulak and Sanya often quarrelled, with the jealous wife accusing her husband of womanising.
They believed the couple might argued while driving, leading to the accident. Police speculated Sanya shot his wife in retaliation and anger, but killing himself in remorse.
More investigation is being done.