A boy whose parents were stabbed to death earlier this week at their home in Sakai, Ibaraki Prefecture, has told police that the assailant was a man acting alone, investigative sources said Thursday.
The 13-year-old boy sustained serious injuries to his legs and arm in the attack early Monday, which took place when he was asleep in a bunk bed in a second-floor room with his 11-year-old sister, who suffered minor injuries to her hands.
Their parents Mitsunori Kobayashi, 48, and Miwa Kobayashi, 50, were murdered in their bedroom, also on the second floor. Autopsies determined they both died from blood loss.
According to the sources, the police believe the assailant entered the house intending to commit murder, as none of the rooms were ransacked.
The son has been quoted as telling the police, "Although I couldn't see (the assailant's) face because it was dark, I think he was alone," the sources said.
The son and his younger sister have said the attacker was wearing a hat and a mask, the sources said.
Their 21-year-old sister, who was in a room on the first floor, was not hurt.
The police suspect the assailant likely gained access from an unlocked entry point on the first floor and headed directly upstairs, the sources said.
According to the sources, Miwa Kobayashi made an emergency call to the police around 12:40 a.m. on Monday. She repeatedly said she was in pain during the call, which lasted around a minute.
Although the police called back, there was no response. The police suspect she was killed immediately after telephoning them, the sources said.