Four members of the Miyazawa family were killed in their Tokyo home.
Updated 12 Aug 2026
Mikio and Yasuko Miyazawa and their children, Niina and Rei, were killed in their home beside Soshigaya Park during the night of 30–31 December 2000. The offender appears to have remained inside for a period after the attack. [1]
Investigators recovered clothing, biological material, fingerprints, and other items believed to have been left by the offender. Despite the unusually large amount of physical evidence and a continuing police investigation, no one has been arrested. [2]
8 sourced milestones
Major events in the case, shown in chronological order.
Mikio and Yasuko Miyazawa and their children Niina and Rei were killed during the night in their home beside Soshigaya Park in Setagaya, Tokyo.
Source: Wikipedia ↗Yasuko's mother entered the house at about 10:40 a.m. and discovered the victims. Police began examining a scene containing an unusually large amount of physical evidence.
Source: Wikipedia ↗Investigators catalogued blood and fingerprints believed to belong to the offender, as well as clothing, a bag, handkerchiefs and the knife used in the attack. Database comparisons did not identify a suspect.
Source: Tokyo Metropolitan Police Department ↗Japan abolished the statute of limitations for murders punishable by death and applied the reform to qualifying cases whose previous limitation periods had not expired, ensuring that the Setagaya investigation could continue indefinitely.
Source: Wikipedia ↗Police used improved image analysis to identify a person who had purchased the same model of knife, but comparison testing did not match the DNA recovered from the scene and the person was ruled out.
Source: Wikipedia ↗The Setagaya Ward Assembly formally asked the national government to expand DNA databases and establish a carefully regulated framework for using additional genetic information in serious unsolved crimes.
Source: Setagaya City ↗FNN reported that specialist analysis commissioned by police estimated that the offender may have been in his thirties at the time of the killings. The estimate has not identified an individual and is presented as reported investigative information.
Source: FNN Prime Online ↗Tokyo Metropolitan Police renewed its appeal for information and maintained a combined reward of up to ¥20 million. The special investigative task force remains active and no suspect has been arrested.
Source: Tokyo Metropolitan Police Department ↗1 video
Structured overview of the timeline and forensic evidence.
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