Japan - Miyazawa family of 4 murdered, Setagaya, Tokyo, 30 Dec 2000 #4

[Lalalacasbah]

If the culprit were actually in his 30’s it would make it infinitely easier for him to commit the murder and remain undetected if he were from a USAF base. Him being in his 30’s eliminates many of the obstacles a teenager would face in the same situation. For me personally a change in age changes nothing but that, rather than the current working theories we have here.

Saying that though, we have recently been able to place the high school students directly next to Mikio’s workplace the same year of the murder, and the years before and after, with proof that includes photos too amongst other things.

It will be interesting as things hopefully keep progressing.

Oh wow! Yes, really really hoping for a break through in any form!

I did read a comment elsewhere where someone mentioned if the age was higher that would explain the large shoe size, but I take that with a grain of salt big time. Lots of teens out there can have big feet.

 

[a7a]

View attachment 533046
Mikio Miyazawa 44, wife Yasuko 41, Niina 8, and Rei 6

"All four were brutally murdered on December 30, 2000 in a crime that shocked Japan and began a grim new chapter in the country's criminal history.

Police know so much about the killer — everything except who he is and why he committed such a violent crime.

He left his DNA everywhere.
He left clothes at the scene.
He left the murder weapon.
He used the victims' computer.
He ate at least four ice creams from their freezer.
And he stayed inside the house for hours as the family lay dead.

Almost 250,000 investigators have worked on this case, receiving more than 15,000 tip-offs from the public.

But nearly two decades later, officers are seemingly no closer to solving a crime that is extremely rare in this largely peaceful country.

[...]"

Please welcome our new verified Websleuths member, FacelessPodcast, a published author who is researching and producing a podcast on NBC Universal about this horrific, unsolved crime. Hopefully some day the brutal killer of this family can be caught and brought to justice.

If FacelessPodcast wishes to share their personal identity, we'll leave it to them to do so.

Thank you to everyone for being here to discuss this case and hopefully help catch this killer. It's been far too long.

Thread #1 Thread #2 Thread #3

I have a theory. First I will lay the information that struck me then deductions and finally the theory.

1. Culprit is believed to be of mixed race (some where of european-south asian descent and east asian)
2. Only Rei was strangled
3.Someone mentionned that there was an affordable housing building behind them
4. Items the culprit left behind were somewhat cheap and indicated they were a teenager
5. Stayed at the house after murdering them
6. most important one: Their DNA didnt match any on the japanese database.

my deductions :
1.Culprit is a sociopath, killed and stayed unfazed at their house as they lay dead. Relieved pressure acted in a way to "solve" an issue.
2.Culprit is one of the kids of an illegal refugee and a japanese person.
3.Culprit was poor and living in that cheap student housing building with his family
4.Culprit may have a younger sibling.
5. Culprit's japanese parent may have died
6. Culprit's foreigner parent may be the mother

My theory:
Refugees in the 2000s did not need to provide DNA samples, therefore the foreigner parents DNA isnt in the japanese database, I am guessing the foreigner parent stayed longer than they should have and became "illegal" which is why they didnt report the culprits birth in a way to protect the foreigner parent from deportation because they would need to report the foreigner adult too. Sociopaths often act in ways to fix problems they see around them and have no regards for consequances and are impulsive. My guess would be that the culprit's younger sibling was getting bullied in kindergarten/school for being mixed race "gaijin" and/or for missing a parent, maybe the kids at the kindergarten/school in Rei's grade were threatening with deporting them and went to get "revenge" on their family which would explain why only Rei was strangled. The other possible theory would be that the culprit is still mixed race but this time a psychopath who got infuriated with the family maybe for the same reason as my first theory but this time he mightve killed them because he felt as if because of his race he was looked down upon, maybe rei's mom didnt let Rei play outside and the culprit took it as an attack and decided to kill them, leaving feces and the eating of 4 ice creams to mock them. I think the culprit used their computer to check if they had told anyone about his "illegal"/ expired stay parent or his undocumented self. He couldve also waited at their house thinking there were more family members that were a threat to him coming later. They lived in apparently student cheap housing, there must be a qualification form and this is why I believe the culprit is a mixed refugee ( probably from an asylum parent europe-southasian i could guess kurd ) who lived in a high school or maybe a university nearby whith his family in his "appartment/dorm" with maybe a younger sibling, I'd like to think that thei rmother wouldnt have had too many years in difference with her two kids, assuming the culprits younger sibling is also 6, the max age for an older sibling without havig too much of a big age gap, standing at around 170 cm who is slim and has european dna too, I would place him between 15-17.


This is my hypothesis, do not steal my theory.
-A

 

[a7a]

I have a theory. First I will lay the information that struck me then deductions and finally the theory.

1. Culprit is believed to be of mixed race (some where of european-south asian descent and east asian)
2. Only Rei was strangled
3.Someone mentionned that there was an affordable housing building behind them
4. Items the culprit left behind were somewhat cheap and indicated they were a teenager
5. Stayed at the house after murdering them
6. most important one: Their DNA didnt match any on the japanese database.

my deductions :
1.Culprit is a sociopath, killed and stayed unfazed at their house as they lay dead. Relieved pressure acted in a way to "solve" an issue.
2.Culprit is one of the kids of an illegal refugee and a japanese person.
3.Culprit was poor and living in that cheap student housing building with his family
4.Culprit may have a younger sibling.
5. Culprit's japanese parent may have died
6. Culprit's foreigner parent may be the mother

My theory:
Refugees in the 2000s did not need to provide DNA samples, therefore the foreigner parents DNA isnt in the japanese database, I am guessing the foreigner parent stayed longer than they should have and became "illegal" which is why they didnt report the culprits birth in a way to protect the foreigner parent from deportation because they would need to report the foreigner adult too. Sociopaths often act in ways to fix problems they see around them and have no regards for consequances and are impulsive. My guess would be that the culprit's younger sibling was getting bullied in kindergarten/school for being mixed race "gaijin" and/or for missing a parent, maybe the kids at the kindergarten/school in Rei's grade were threatening with deporting them and went to get "revenge" on their family which would explain why only Rei was strangled. The other possible theory would be that the culprit is still mixed race but this time a psychopath who got infuriated with the family maybe for the same reason as my first theory but this time he mightve killed them because he felt as if because of his race he was looked down upon, maybe rei's mom didnt let Rei play outside and the culprit took it as an attack and decided to kill them, leaving feces and the eating of 4 ice creams to mock them. I think the culprit used their computer to check if they had told anyone about his "illegal"/ expired stay parent or his undocumented self. He couldve also waited at their house thinking there were more family members that were a threat to him coming later. They lived in apparently student cheap housing, there must be a qualification form and this is why I believe the culprit is a mixed refugee ( probably from an asylum parent europe-southasian i could guess kurd ) who lived in a high school or maybe a university nearby whith his family in his "appartment/dorm" with maybe a younger sibling, I'd like to think that thei rmother wouldnt have had too many years in difference with her two kids, assuming the culprits younger sibling is also 6, the max age for an older sibling without havig too much of a big age gap, standing at around 170 cm who is slim and has european dna too, I would place him between 15-17.


This is my hypothesis, do not steal my theory.
-A

I could also add that I think it might be the mother who was foreign because then they couldve reported the birth without a father because she couldve claimed she didnt know the after plus japan is big on privacy so there wouldnt be any issue for a japanese woman to give birth and reporting it contrary to an "illegal" woman, plus her dna isnt reported the database which would explain why the culprit doesnt match to anyone.I also said they might be a 1 parent family because wouldnt need to take such cheap housing (poor= no job or low paying one in factory because its illegal for them to work and they could rent using the japanese parents name but they havent done that which lead me to believe the father isnt present but the culprit still wears his stuff (someone mentionned about a clue indacting he couldve been 30) and then sand might come from the mothers native land. I said he mightve lived in a high school or university nearby, i meant went*. I thought I had added them in my first post but had not so im adding them right now.The large shoe size might be because the culprit has seen himself as the man of the house since his father wasnt around anymore, maybe he wore his fathers clothing (shoes) to feel as the man of the house whilst doing what he felt he needed to do

Do not steal my hypothesis/theory/deductions.
-A

 

[a7a]

I could also add that I think it might be the mother who was foreign because then they couldve reported the birth without a father because she couldve claimed she didnt know the after plus japan is big on privacy so there wouldnt be any issue for a japanese woman to give birth and reporting it contrary to an "illegal" woman, plus her dna isnt reported the database which would explain why the culprit doesnt match to anyone.I also said they might be a 1 parent family because wouldnt need to take such cheap housing (poor= no job or low paying one in factory because its illegal for them to work and they could rent using the japanese parents name but they havent done that which lead me to believe the father isnt present but the culprit still wears his stuff (someone mentionned about a clue indacting he couldve been 30) and then sand might come from the mothers native land. I said he mightve lived in a high school or university nearby, i meant went*. I thought I had added them in my first post but had not so im adding them right now.

Do not steal my hypothesis/theory/deductions.
-A

@FacelessPodcast

 

[Lalalacasbah]

I have a theory. First I will lay the information that struck me then deductions and finally the theory.

1. Culprit is believed to be of mixed race (some where of european-south asian descent and east asian)
2. Only Rei was strangled
3.Someone mentionned that there was an affordable housing building behind them
4. Items the culprit left behind were somewhat cheap and indicated they were a teenager
5. Stayed at the house after murdering them
6. most important one: Their DNA didnt match any on the japanese database.

my deductions :
1.Culprit is a sociopath, killed and stayed unfazed at their house as they lay dead. Relieved pressure acted in a way to "solve" an issue.
2.Culprit is one of the kids of an illegal refugee and a japanese person.
3.Culprit was poor and living in that cheap student housing building with his family
4.Culprit may have a younger sibling.
5. Culprit's japanese parent may have died
6. Culprit's foreigner parent may be the mother

My theory:
Refugees in the 2000s did not need to provide DNA samples, therefore the foreigner parents DNA isnt in the japanese database, I am guessing the foreigner parent stayed longer than they should have and became "illegal" which is why they didnt report the culprits birth in a way to protect the foreigner parent from deportation because they would need to report the foreigner adult too. Sociopaths often act in ways to fix problems they see around them and have no regards for consequances and are impulsive. My guess would be that the culprit's younger sibling was getting bullied in kindergarten/school for being mixed race "gaijin" and/or for missing a parent, maybe the kids at the kindergarten/school in Rei's grade were threatening with deporting them and went to get "revenge" on their family which would explain why only Rei was strangled. The other possible theory would be that the culprit is still mixed race but this time a psychopath who got infuriated with the family maybe for the same reason as my first theory but this time he mightve killed them because he felt as if because of his race he was looked down upon, maybe rei's mom didnt let Rei play outside and the culprit took it as an attack and decided to kill them, leaving feces and the eating of 4 ice creams to mock them. I think the culprit used their computer to check if they had told anyone about his "illegal"/ expired stay parent or his undocumented self. He couldve also waited at their house thinking there were more family members that were a threat to him coming later. They lived in apparently student cheap housing, there must be a qualification form and this is why I believe the culprit is a mixed refugee ( probably from an asylum parent europe-southasian i could guess kurd ) who lived in a high school or maybe a university nearby whith his family in his "appartment/dorm" with maybe a younger sibling, I'd like to think that thei rmother wouldnt have had too many years in difference with her two kids, assuming the culprits younger sibling is also 6, the max age for an older sibling without havig too much of a big age gap, standing at around 170 cm who is slim and has european dna too, I would place him between 15-17.


This is my hypothesis, do not steal my theory.
-A

Very intriguing theory! I think it's good to think outside the box and I do think it's smart to consider all avenues. I have so many questions about your theory!

Do you think the culprit and his younger sibling were results of a love affair, brief affair, marriage or something else? You think it was a single mother raising the 2 on her own, is that right?

I am curious the tensions in schools over "gaijin" or mixed race. Some posters on here who know Japan culture might know...Are children as young as Rei really aware of that in Japan? I guess might be if they learn it from home or the parents are not wanting Rei to play with said child as mentioned.

Why are you thinking Kurd background? Are you thinking Yasuko had interactions with the single mom in the park, store or neighborhood where the older sibling/culprit noticed some form of "dissing" or judgment/differential treatment kinda thing?

How old do you think the culprit actually was?

 

[SteveL]

Ishihara to visit Yokota Air Base

Tokyo Gov. Shintaro Ishihara said Friday that he will pay a visit on June 2 to Yokota Air Base, whose return the outspoken governor has pledged.

www.japantimes.co.jp

A lot of players and politics involving Yokota.

 

[Cryptic]

I can't remember if the college/university student idea was looked into, I thought there was discussion about a university in the thread

A possible University connection was raised, though not formally. The possibility of was centered on a connection to the mother's position as a cram school teacher. Say.....

The completely fictional "David Lau": "David" is a Malaysian citizen of Chinese ethnicity. In secondary school, he earned a reputation for being a talented athlete, but also for getting kicked off of a series of sports teams for needless aggression, fighting with team mates, constant fouls etc.

"David" also has another characteristic in that he is 1/8 European stemming from a romance between a local girl and a contracted Dalmation pipe fitter at a Royal Navy Base in then UK colonial Malaysia. His European features, however, are slight and David jokes that his background improved his "John Mcenroe" fueled tennis game.

"David" arrives in Japan as a university student and quickly discovers the "good life" of parties and night clubs until..... finals arrive. Attempting to salvage his grades and family honor, David hires the mother as a tutor. True to form, David blames everybody but himself when his grades tank. Enraged, David..... .

 

[UnDiluted7]

I have a theory. First I will lay the information that struck me then deductions and finally the theory.

1. Culprit is believed to be of mixed race (some where of european-south asian descent and east asian)
2. Only Rei was strangled
3.Someone mentionned that there was an affordable housing building behind them
4. Items the culprit left behind were somewhat cheap and indicated they were a teenager
5. Stayed at the house after murdering them
6. most important one: Their DNA didnt match any on the japanese database.

my deductions :
1.Culprit is a sociopath, killed and stayed unfazed at their house as they lay dead. Relieved pressure acted in a way to "solve" an issue.
2.Culprit is one of the kids of an illegal refugee and a japanese person.
3.Culprit was poor and living in that cheap student housing building with his family
4.Culprit may have a younger sibling.
5. Culprit's japanese parent may have died
6. Culprit's foreigner parent may be the mother

My theory:
Refugees in the 2000s did not need to provide DNA samples, therefore the foreigner parents DNA isnt in the japanese database, I am guessing the foreigner parent stayed longer than they should have and became "illegal" which is why they didnt report the culprits birth in a way to protect the foreigner parent from deportation because they would need to report the foreigner adult too. Sociopaths often act in ways to fix problems they see around them and have no regards for consequances and are impulsive. My guess would be that the culprit's younger sibling was getting bullied in kindergarten/school for being mixed race "gaijin" and/or for missing a parent, maybe the kids at the kindergarten/school in Rei's grade were threatening with deporting them and went to get "revenge" on their family which would explain why only Rei was strangled. The other possible theory would be that the culprit is still mixed race but this time a psychopath who got infuriated with the family maybe for the same reason as my first theory but this time he mightve killed them because he felt as if because of his race he was looked down upon, maybe rei's mom didnt let Rei play outside and the culprit took it as an attack and decided to kill them, leaving feces and the eating of 4 ice creams to mock them. I think the culprit used their computer to check if they had told anyone about his "illegal"/ expired stay parent or his undocumented self. He couldve also waited at their house thinking there were more family members that were a threat to him coming later. They lived in apparently student cheap housing, there must be a qualification form and this is why I believe the culprit is a mixed refugee ( probably from an asylum parent europe-southasian i could guess kurd ) who lived in a high school or maybe a university nearby whith his family in his "appartment/dorm" with maybe a younger sibling, I'd like to think that thei rmother wouldnt have had too many years in difference with her two kids, assuming the culprits younger sibling is also 6, the max age for an older sibling without havig too much of a big age gap, standing at around 170 cm who is slim and has european dna too, I would place him between 15-17.


This is my hypothesis, do not steal my theory.
-A

You make a number of assumptions that I don't see supported in any real way in the evidence publicly available.

- The idea that Rei was targeted due to school bullying or that the killer was retaliating for perceived racism is speculative. There’s no public evidence that Rei was involved in bullying or that the family had any known conflict with neighbours.
- While the DNA evidence suggests mixed ancestry (East Asian and possibly European or South Asian), this doesn’t necessarily imply refugee status or illegality. Japan has a small but present population of mixed-race individuals who are legally documented.
- The idea that the killer’s birth was unregistered to protect an undocumented parent is plausible but speculative. It would require more evidence to support.
- Police reportedly conducted DNA tests on hundreds of local residents, including those in the housing complex. If the killer lived there, it’s unclear why no match was found, unless, as you suggest, they were never registered. But this would require the entire family to be undocumented, which is rare and risky in Japan.
- Touching on the feces, ice cream etc... These actions could be interpreted in many ways: mockery, mental illness, or simply a lack of concern. While your theory sees them as symbolic acts of revenge or contempt, they could also be signs of disorganized thinking or psychosis.

Your theory is compelling in that it tries to reconcile several puzzling aspects of the case, especially the unmatched DNA and the killer’s behavior. However, it relies heavily on speculative elements (e.g., the killer’s family background, motive, and age) that aren’t supported by public evidence.

That said, in the absence of a resolution, such theories can be useful for generating new investigative angles.

 

[Charlot123]

I just re-read about Jack the Ripper. While I do not subscribe to the theory of Kosminski, several comments sounded interesting. Mainly, that the perpetrator was less likely to be a mysterious aristocrat and more likely, the inhabitant of Whitehapel, not too different socio-economically from the victims and living close by.

By the same principle, we have been always looking for someone who stood out in the community. I am starting to think that the perpetrator is someone ordinary who lived not too far.

About the DNA, what I don't know yet is whether we are discussing mitochondrial + Y, or autosomal DNA.

Because if we assume that mother was "from Southern Europe" based on mitochondrial DNA, we may be wrong and she might be as Japanese as they come. No matter her mitotype. Same for Y. I don't think that the Tokyo police has specifically explained what DNA they were looking at, did they? It was a leak, if i remember correctly.

 

[UnDiluted7]

I just re-read about Jack the Ripper. While I do not subscribe to the theory of Kosminski, several comments sounded interesting. Mainly, that the perpetrator was less likely to be a mysterious aristocrat and more likely, the inhabitant of Whitehapel, not too different socio-economically from the victims and living close by.

By the same principle, we have been always looking for someone who stood out in the community. I am starting to think that the perpetrator is someone ordinary who lived not too far.

About the DNA, what I don't know yet is whether we are discussing mitochondrial + Y, or autosomal DNA.

Because if we assume that mother was "from Southern Europe" based on mitochondrial DNA, we may be wrong and she might be as Japanese as they come. No matter her mitotype. Same for Y. I don't think that the Tokyo police has specifically explained what DNA they were looking at, did they? It was a leak, if i remember correctly.

You're absolutely right to question the assumptions around the DNA evidence in the Setagaya case, especially regarding what kind of DNA was analyzed and how conclusions were drawn.

The Tokyo Metropolitan Police have never officially released a full forensic breakdown, but leaked information and investigative reporting over the years have revealed the following:

- Y-chromosome DNA (paternal line): The suspect’s Y-DNA belongs to haplogroup O-M122, which is common in East Asian populations:
~25% of Koreans
~10% of Chinese
~8% of Japanese males

- Mitochondrial DNA (maternal line): The maternal haplogroup reportedly pointed to Southern European or Caucasus ancestry, possibly from the Mediterranean, Adriatic, or even Kurdish regions.
- Autosomal DNA: There’s no public confirmation that autosomal DNA (which would give a more complete picture of ancestry) was analyzed or disclosed. Most of the ancestry conclusions seem to be based on haplogroup analysis, which, as you rightly pointed out, only tells us about one line of inheritance (maternal or paternal).

You're spot on in saying that haplogroups don’t define ethnicity or nationality. A person with a Southern European mitochondrial haplogroup could still be culturally and nationally Japanese. Similarly, the paternal haplogroup O-M122 is widespread in East Asia and doesn’t narrow things down much.

So yes, the idea that the suspect’s mother was “Southern European” is not definitive, it’s a probabilistic inference based on limited genetic markers. It’s also worth noting that these findings were leaked, not part of an official public release, so we’re working with second-hand interpretations.

Based on that, what can we conclude?

- The suspect was male, likely 15–22 years old at the time.
- He had mixed ancestry, with East Asian paternal and possibly European maternal lineage.
- His DNA and fingerprints did not match any in Japanese databases, suggesting he may not have been a registered citizen or had no prior criminal record.

Beyond that, a lot of the statements in here are wild leaps to conclusion based on assumptions.

 

[FaerieDust]

IF the mother was European (big if, as mentioned above), she could have been a university lecturer or foreign language teacher at the university, and the son/killer was born abroad to the Japanese father before they moved back to Japan.
Or, he was just born abroad and so never registered? ...I had a classmate who was born to a Japanese mother and British father, lived all his life in the UK then went to Japan to live after he left high school because he preferred the culture, knew the language and also didn't look mixed heritage so felt he fit into society better there.

 

[UnDiluted7]

IF the mother was European (big if, as mentioned above), she could have been a university lecturer or foreign language teacher at the university, and the son/killer was born abroad to the Japanese father before they moved back to Japan.
Or, he was just born abroad and so never registered? ...I had a classmate who was born to a Japanese mother and British father, lived all his life in the UK then went to Japan to live after he left high school because he preferred the culture, knew the language and also didn't look mixed heritage so felt he fit into society better there.

You're absolutely right to question the assumptions around the killer’s maternal background. One important clarification is that mitochondrial DNA (mtDNA) cannot determine nationality, it only traces deep ancestral lineage along the maternal line, which can go back hundreds or even thousands of years. So even if the mtDNA haplogroup is common in Southern Europe or the Caucasus, that doesn’t mean the mother was necessarily European in any cultural or national sense, she could have been Japanese or from any number of backgrounds.

Also worth noting: the Tokyo Metropolitan Police have never confirmed whether autosomal DNA, which provides a much more complete picture of a person’s ancestry, was analyzed or used in profiling the suspect. Most of what we know about the DNA comes from leaked reports, not official disclosures, so any conclusions about the suspect’s heritage should be treated with caution.

 

[Cryptic]

The maternal haplogroup reportedly pointed to Southern European or Caucasus ancestry, possibly from the Mediterranean, Adriatic, or even Kurdish regions.

Thank you for the clarification that the DNA sample only suggests possibilities, and is not definitive in regards to ethnic origins.

But.... your reference to Kurdish areas is interesting. Some Croat folk legends- as well as some DNA indications, cultural practices, word origins and folk art etc. suggest that the Croats are not originally a Slavic people (though they speak a Slavic language today).

Rather, some interpretations- and interpretations only, of those aspects above suggest that Croats originated in..... North West Iran of all places. And, by extension, were originally an Iranian people.

Iran Chamber Society: History of Iran: Identity of Croatians in Ancient Iran

Iranian Historical & Cultural Information Center

www.iranchamber.com

Sure, it could all be legends. But.... it is pretty interesting that the DNA sample could (key word) indicate somebody from the Adriatic (Croatia), or northwest Iran.

 

[UnDiluted7]

Thank you for the clarification that the DNA sample only suggests possibilities, and is not definitive in regards to ethnic origins.

But.... your reference to Kurdish areas is interesting. Some Croat folk legends- as well as some DNA indications, cultural practices, word origins and folk art etc. suggest that the Croats are not originally a Slavic people (though they speak a Slavic language today).

Rather, some interpretations- and interpretations only, of those aspects above suggest that Croats originated in..... North West Iran of all places. And, by extension, were originally an Iranian people.

Iran Chamber Society: History of Iran: Identity of Croatians in Ancient Iran

Iranian Historical & Cultural Information Center

www.iranchamber.com

Sure, it could all be legends. But.... it is pretty interesting that the DNA sample could (key word) indicate somebody from the Adriatic (Croatia), or northwest Iran.

Absolutely fascinating connection you're drawing there. The idea that the maternal haplogroup could point to either the Adriatic (e.g., Croatia) or northwest Iran really highlights how deep-time genetics can blur modern national boundaries.

But it's important to keep in mind that mitochondrial DNA only traces maternal lineage and reflects deep ancestral origins, often going back hundreds or thousands of years. It doesn’t tell us anything definitive about a person’s nationality, culture, or even recent family history.

Also, the Tokyo Metropolitan Police have never confirmed whether they analyzed autosomal DNA, which would give a much more comprehensive picture of the suspect’s ancestry. Most of what we know about the DNA comes from leaked reports, not official disclosures.

So while the Kurdish-Croat connection is a fascinating historical and anthropological thread, we should be cautious not to over-interpret the mtDNA findings in the Setagaya case. Still, it’s a great reminder of how interconnected human populations are, and how much history can be hidden in our genes.