Don Muang police reported that Jamroen Phonpayoong, a former official of the Aeronautical Engineering Directorate, shot himself in his two-storey house in Bangkok’s Don Muang district, as a neighbour had reported.

Investigators found that Jamroen used a self-made pen gun to shoot himself.

His nephew, Kittikhun Laipita, 29, said the relatives did not question his death because of the apparent evidence – the hand-written suicide note.

“Jamroen’s wife passed away three months ago. He showed no suicidal signs, though he was depressed” Kittikhun said.

Jamroen’s note read: “I have committed suicide without others related because I had promised to my wife that when she died, I would follow her, so please understand my reason.”

Police are still checking circumstantial evidence and quizzing relatives to understand the deceased’s motive.