This Family Was Found Murdered In Their Home, And Their Killer Hung Out For Hours, Eating Their Food Before Leaving

On December 31, 2000, the Miyazawa family was found murdered in their home in the Kamisoshigaya neighborhood of Setagaya. Mikio and Yasuko Miyazawa, along with their daughter Niina and their son Rei, were murdered by an unknown person.

Afterward, the killer remained in their home for several hours before disappearing. Despite extensive evidence, the perpetrator has never been identified, and the case remains unsolved.

The bodies of 44-year-old Mikio, 41-year-old Yasuko, eight-year-old Niina and six-year-old Rei were discovered by Yasuko's mother at 10:40 a.m. on December 31. Mikio, Yasuko, and Niina were stabbed to death, while Rei was strangled.

The Tokyo Metropolitan Police Department determined that the family was murdered between December 30 at 11:30 p.m. and December 31 at 12:05 a.m.

Investigators believe the killer entered through an open window in the second-floor bathroom at the back of the house. The bathroom window screen and muddy footprints were found on the ground outside.

He may have also scaled the fence, climbed up the air conditioning box, and removed the window screen himself. The killer then entered Rei's bedroom on the second floor and strangled the boy with his bare hands.

According to some reports, Mikio heard the disturbance and rushed up the stairs to confront the killer. He fought and injured the killer until he was stabbed in the head with a sashimi bōchō knife. The killer attacked Yasuko and Niina with the broken knife. He used a santoku knife in the house to murder them.

Afterward, the killer remained in the house for two to 10 hours. He used the family computer, drank four bottles of barley tea, and ate melon and four ice creams from the refrigerator.

He used the toilet without flushing it, leaving his feces in the toilet. He also treated his injuries with first aid kits and other sanitary products.

Gautam - stock.adobe.com - illustrative purposes only - pictured above is a house at night

He ransacked drawers and papers and took some money. He left behind a knife, hip bag, hat, scarf, jacket, gloves, and two handkerchiefs. Mikio's computer had been connected to the internet the morning after the murders, from 1:18 a.m. to 1:23 p.m.

Around 10 a.m., Yasuko's mother, Haruko, visited the house after being unable to reach her daughter. She rang the doorbell, but no one answered.

When she went inside and discovered the horrific scene, she accidentally jerked her arm against the computer mouse, causing the computer to wake up.

An analysis of the feces revealed that the killer had eaten string beans and sesame seeds the day before the murders. The clothes and sashimi knife had been purchased in Kanagawa Prefecture.

The shirt that the killer left behind was rare; only 130 of them were made and sold. However, the police have only tracked down 12 of the people who bought the shirts.

Inside the hip bag, trace amounts of sand were detected. The sand came from the Nevada desert, more specifically the area of Edwards Air Force Base in California, and a skate park in Japan.

The killer's DNA and fingerprints were found throughout the house, but none matched the databases. It is estimated that the killer was at least in his thirties at the time of the murders, according to the most recent reports from 2025. He is likely right-handed and possibly mixed-race.

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