Japan Today



Police still hoping killer's DNA will break 20-year-old Setagaya multiple murder case


Tokyoites who arose on the morning of Jan 1, 2001 with hopeful expectations for the new year and new millennium were greeted instead with shocking news headlines: "Police suspect burglary after family found slain at home."

In police parlance, the official name is "Kamisoshigaya 3-chome family of four murder case." The murders of four family members Mikio Miyazawa (age 44), his wife Yasuko (41), daughter Niina (age 8) and son Rei (6) occurred on the night of Dec 30, 2000.

Now 20 years on, the case remains no closer to a solution.

As no blood was found on Rei's body, it is theorized that the killer murdered him first by strangulation. The father, wife and daughter died of exsanguination from multiple knife wounds. Afterwards the killer inexplicably lingered in the house possibly for as long as 10 hours and then departed, leaving behind his blood, fingerprints, an unflushed stool in the toilet and various personal possessions that investigators typically call takara no yama (a mountain of treasures, i.e., evidence).

None of these, however, have led to the arrest of any suspect. It's as if he had walked out the door, boarded a UFO, and vanished into thin air.

Asahi Geino (Dec 31-Jan 7) talked with retired police official Takeshi Tsuchida, who as chief of the Seijo Police station headed the initial investigation.

"After killing his victims the criminal lingered in the house," says Tsuchida. "He ate two cups of ice cream straight from the cups without a spoon. He scattered documents into the bathtub. He may have been looking for something, or perhaps he was just spending time before leaving."

The greatest mystery perhaps remains the killer's motive.

"Several hundred thousand yen are believed to have disappeared, but the question remains, were the killings done for financial gain, out of some deep-seated personal hatred or the act of a deviant personality?" Tsuchida wonders.

"Nothing seems to make sense. The killer brought gloves, but from the beginning committed the killings barehanded. Normally if premeditated, a killer would have worn gloves. It also seems strange that instead of a survival knife he choose a slender knife, used for slicing sashimi, called a Yanagiba hocho. Its blade is unsuitable for stabbing humans. And there's something inconsistent with criminal premeditation in the way he broke into a house with the lights out and killed the entire household."

The killer's unusual DNA indicates a father of East Asian background and a mother with roots in southern Europe or the Adriatic. With only 2% of genetic material, scientists can develop a profile -- similar to a sketch by a police artist -- of the individual's likely physical appearance. The data can also be cross-referenced to ancestry sites on the web that might lead to other family members and trace the killer's identity. Widely used by law enforcement in the U.S., such science has led to the arrest of several serial killers.

But Japan lags behind other countries in these techniques, and in addition, the law prevents exploratory profiles of crime suspects from being made public. For authorities to make public the names and photographs of murder victims but protect suspected perpetrators strikes Tsuchida as highly inequitable.

"If we could generate a montage photo (composite image) based on the DNA, perhaps someone in the neighborhood might recall having seen him, and provide some useful clue," he says.

"This incident is a barometer of public safety in Japan," Tsuchida remarks. "People find it terrifying that something like this could happen in such a secure neighborhood, in the safety of a family home.

"When people ask me, 'What became of that incident in Setagaya?' I'm at a loss for words. If we can't generate a facial image based on the DNA, it might as well be as if we had no DNA at all. If we can track down this killer, I believe it will help to deter similar crimes in the future."

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How about applying some AI? All data of that time , from ward office citizen data , local and nationwide print or TV news around that day up to nearer video footage from businesses, roads, buildings, convenience stores etc. as hash input and then Keras, TensorFlow and co. spits out some listed prints to follow traces and interview people from there , having been there but now moved away or having come from outside on those days 20 years ago. Mass DNA testing isn’t such a problem nowadays too. There are also good investigation teams in the U.S. , maybe they will help or can be temporarily rented , as well as software solutions especially predestined for such cases, like palantir et. al. Plenty of possibilities, that crazy killer isn’t as safe as he or she might still think.

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That "treasure trove" of evidence may have made the police overconfident they could get him easily. But as for video footage, the crime scene was in a very isolated area with nothing adjacent except a couple of parks and empty land on three sides and a small river to the west. No businesses and only a narrow street.

I am almost led to wonder if the perp was put into some sort of hypnotic trance and has no memory of what he did. Sort of like the Manchurian Candidate. I realize that is the stuff of science fiction, but there's nothing else that satisfactorily explains the killer's behavior.

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One of the parents of the suspected perp was of European lineage, and no relatives have been found in the Japanese DNA database, is that correct? Then perhaps the individual linked to the available DNA does not have any relatives in Japan.

I suspect that the police have already done so, but it would seem to be necessary to search the DNA databases of every possible country from which the suspect may have come. Normally that would not be done, but given the nature of the crime, it seems needed.

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"I suspect that the police have already done so, but it would seem to be necessary to search the DNA databases of every possible country from which the suspect may have come. Normally that would not be done, but given the nature of the crime, it seems needed."

That's not how it's done!

Police can ONLY check the DNA of an individual arrested for any recordable offence.

And the police in the US do not have any jurisdiction outside of their country's borders.

Did you really think they have the power to check people's DNA at their own pleasure?!

Unless you live in China....

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@NCIS Reruns (I'm told Ziva's back)

"...some sort of hypnotic trance..."

You may be thinking of something akin to a 'fugue state'. These states can be induced, typically in highly traumatized individuals, and these techniques are used extensively by suicide bomb recruiters upon their orphaned or otherwise traumatized recruits who they manipulate and then send out on contracted bombings. Few groups have the inhouse expertise and contracting suicide bombs is a profitable business in various areas of our world. In a fugue state, rationality is suspended. Oddly, such a state can be very useful in emergencies when 'doing' far outweighs 'thinking' and thinking is put aside and one operates like a machine. It's an interesting experience to recall (How the H*ll did I do that...!!??).

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Read the description of Sirhan Sirhan immediately following his shooting of Robert Kennedy.

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"If after this amount of time they haven't closed the case based on the evidence they have, they are not going to."


Samuel Little killed nearly 100 women and it took over 30 years to get caught.


Did his "first" job in 1974, kept on going until his arrest in 2005.

Ted Bundy?

With a tally of over 30, approximately a decade of police blunders, prison escapes, and all.

And all of this in the good old US of A.

"Best" police, in the World,

As they keep on telling us.

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Agree with Expat. Given that the suspect is of mixed ancestry they may well have access to a non-Japanese passport and able to live the rest of their life outside of Japan. If that's the case then I can't imagine the J-police ever catching him - he would be stupid to come back given the risk.

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There have been cases over here where knowledgeable civilians have solved criminal cases that the professionals did not know how to solve. These days, much of the DNA information is in the public realm, and does not require a warrant to search. Given the extreme violence and cruelty of the crime described in the article, it seems reasonable to search the DNA database of every country on Earth that allows it.

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it seems reasonable to search the DNA database of every country on Earth that allows it.

Interpol maintains a large DNA database of material from 85 countries and the J-police have been checking it periodically. No luck so far.


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he choose a slender knife, used for slicing sashimi, called a Yanagiba hocho. Its blade is unsuitable for stabbing humans.

Seems to have done the trick though. What a bizarre thing to say!

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I think that all this thing has something to do with serial cats killings. And if I'am right - a person behind cats killing and a person behind Setagaya murders...it's a same person and that person probably still lives in the same area? Serial cat murders happend in 2009 and it happend in the same area as family murders. The police received reports of injured or dead cats then he/she stopped again for fear of being caught. So maybe that person just couldn't control himself so he/she passed on cats? And all those things that he/she left in crime scene (that sand from USA for example)....maybe he/she did that on purpose? To mislead? I think this person is very smart because he / she has been able to avoid justice for so many years and probably was abused as child by his/her own family or was bullied at school or both.

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Man. Saw a quick image of the family and must say it's tragic. An entire family gone like that and a killer on the loose. I mean I agree with some of the profiles. Possible skater at that time. There was accounts of Mikio arguing with skaters, or maybe people around the park. He may have pissed someone off and they took it out on him later that night. Might mean the person did live in that area. Another thing was there was one site that said based on clothes abandoned, they had an image somewhere else of the killer so that would establish a location. Couldn't hurt to start there and work outward. They also have potential age, fingerprints, DNA, and honestly the laws of Japan and many countries for that matter should be changed to help prevent these things. I believe statute of limitations shouldn't be a thing. Why help someone commit a crime and get away with it? Why "protect" anyone with DNA from paying for what they have done where applicable? There are so many things that could be better about the world where this person may have likely been caught already. Who knows though? May e the person who did this is dead and that is what prevented him from being caught. If he never had the chance to commit a crime again, he likely would slip under the radar. Honestly, besides the lack of closure, that would probably be for the best. May the family RIP, my respects to the family and their families as well. Makes me wonder what they would have accomplished or where they would be if they were still alive.

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