The bodies of Akihiro Owa and his son Masaaki were found hanging from the ceiling of their plush hotel room here on Monday.
The Nagano natives both died of asphyxia by hanging, National Bureau of Investigations city forensics chief Nestor Satur told reporters.
The two killed themselves after the management of the hotel allegedly challenged them over a P400,000 check they issued in favor of the hotel last week, said Chief Inspector Aristides Macatangay.
"We are 95 percent sure that the demand letter had triggered the suicide. We concluded that it was suicide because of the result of the autopsy. Besides, everything inside the room was in order and there was no showing of foul play," he added.
The two checked into the hotel on June 7. AFP, Freeman News Service