Police in Kyushu said Saturday that a 41-year-old man is suspected of killing his three children and that he may have originally been planning to take his own life.
The body of a 9-year-old boy, later identified by Fukuoka police as Hiroto Tanaka, was found in an apartment in Iizuka, Fukuoka Prefecture, on Thursday, and those of a 3-year-old boy and 2-year-old girl were found in a hotel in the city of Kagoshima on Friday.
The three children lived with the man in the apartment in which the eldest boy's body was found.
On Friday night, investigators forced their way into a Kagoshima hotel room where the man and the two younger children had been staying since Wednesday, according to the police.
The father jumped from the fourth floor of the hotel, sustaining injuries to his torso, and was taken to a hospital, the police said. No other details about his condition were immediately available.
In the hotel room, which is about 230 kilometers south of their home, the investigators found the bodies of the two children with visible wounds, along with a suicide note, the police said.
Earlier, police said an autopsy on the boy found dead Thursday was inconclusive as to the cause of death. He had been dead for about a week with no visible injuries to his body.
According to the police, the man rented a car in Fukuoka city on Feb. 18 and was supposed to return it last Monday. However, it was discovered at a commercial facility in Miyazaki Prefecture on Thursday.