A former policeman shot himself in his rented Prachin Buri house early on Wednesday, police said.
The Muang Prachin Buri police station was alerted of the suicide at 12.30am.
The body of Pol Sr Sgt-Major Patiphat Prempran, 55, a former border patrol policeman, was found lying in front of a closet on the ground floor of the two-storey townhouse. He had a gunshot wound to his left temple and his 9mm pistol was found nearby.
His wife, Angkhana Prempran, 63, told police she was watching TV when she heard a gun fire and found her husband already dead.
Angkhana said Patiphat took an early retirement in 2013 and worked as a driver for a local politician. She said he used to complain about his Bt800,000 debt with a police savings cooperative and said he would like to die because of the debt.