Chapter 397: The Mystery of the Family Extermination Cold Case

The Toshima family extermination case at the time drew enormous public attention; the horrific scene shocked even the veteran detectives of Investigation Division 1, and the Metropolitan Police Department immediately established a Special Investigation Headquarters and began investigating the case step by step.

They soon made a discovery.

On the night of February 23, the perpetrator (estimated to be a single person) during the period from evening to late night that day, taking advantage of the fact that neighborhood activity was high and noise was loud during the holiday, quietly infiltrated the Sato family's cramped backyard; he/she may have done so by climbing the low fence or using the courtyard clutter as cover.

The perpetrator lay in wait inside the backyard tool shed for a considerable time (several hours), leaving clear muddy footprints (heels severely worn), a crushed empty energy drink can (Red Bull, no DNA/fingerprints), and several strands of dark brown/black synthetic fiber (from clothing or a backpack).

Evidence shows the perpetrator observed the family of four celebrating the short holiday inside through a gap in the curtains that had not been fully drawn; slight fresh scratches and a blurred palm print were found on the rear windowsill,

meaning the perpetrator had observed the Sato family for a long time in the vicinity, while the Sato family remained completely unaware.

This is truly bone-chilling.

Uesugi Muneyuki continued:

"After the whole family fell asleep (after approx. 1:30 AM), the perpetrator emerged from the tool shed, used a sturdy nylon climbing rope found inside the tool shed — the rope was not a Sato family item, recently purchased, common brand — and strangled the watchdog (a small Shiba Inu) to prevent it from barking; the dog's body was abandoned in a corner of the backyard.

Subsequently, the perpetrator used a paving brick found in the backyard to smash the glass sliding door connecting the living room and kitchen, and entered the interior. Shattered glass littered the floor, but the perpetrator seemed extremely familiar with the Sato house's internal structure, deliberately avoiding the main walking paths.

The perpetrator first entered the master bedroom on the first floor, used a personally carried ice pick with a special serrated blade to deliver multiple fatal stabs to the sleeping Kenichi and Miwako, concentrated on the chest and abdomen. The two died with almost no resistance. The scene had large amounts of spatter bloodstains."

"Afterward, the perpetrator went upstairs to the second floor first, entered Shōta's room. Shōta may have been awakened by sounds from downstairs; there were signs of a brief struggle, and finally the perpetrator stabbed Shōta to death with the same ice pick, wounds concentrated on the neck and chest; afterward Riko may have been awakened by the struggle sounds, ran to the stairwell entrance to check. The perpetrator caught up to her at the stairwell entrance and stabbed her to death with the ice pick."

If the above content still only falls within the scope of a normal family extermination case, then the Metropolitan Police's subsequent investigation of it is the source of utter bafflement.

After committing the crime, the perpetrator did not leave the scene at the first opportunity!

He entered the first-floor kitchen, took out a bottle of Korean-produced Cheongnae clear rice wine from inside, paired it with the tangerines on the table, and just like that brazenly ate and drank his fill; he even attempted to cook instant noodles, and used the microwave to heat food from the refrigerator to eat with it!

A banquet at the murder scene?

The Japanese police to this day have not figured out the perpetrator's logic; he even voluntarily left saliva and glove prints.

After eating and drinking his fill, the perpetrator calmly washed his hands; at this point he still had not left, but instead turned on the video player, took out the Sato family's carefully recorded family gathering video tape, and just like that sat on the sofa and watched for a full 45 minutes and used the remote control, until the prompt to change discs came up he still seemed reluctant to stop; he took a roll of Band-Aids and bandages from the medical kit, and left a Trek size 42 shoe print nearby.

After that, the perpetrator finally seemed to intend to leave; he took the 100,000-plus yen in cash from the master's drawer, but did not even glance at the mistress's jewelry and bankbook; worth noting, he specifically took the master's Zippo lighter (discovered missing during later examination).

Finally, the perpetrator left the murder weapon ice pick on the table, and even deliberately arranged the tangerines into the death poses of the family of four; at approx. 4:00 AM, the perpetrator left via the same smashed glass door, crossed the courtyard, and climbed over the backyard fence at a relatively concealed spot. The mud outside the fence in the small alley retained the same 42 Trek shoe prints as inside, but they soon disappeared in the direction of the main road. Holiday morning, there were almost no witnesses on the road, and the road lacked surveillance.

The Japanese police initially had great confidence in solving this case, because the perpetrator left far too many pieces of evidence and leads.

Blood typing showed type A; from skin tissue/bloodstains in Shōta's fingernails, saliva on the shochu drinking cup, and mixed DNA on the ice pick handle, the same unknown male's Y-chromosome DNA (Y-STR) was extracted; analysis showed this DNA possesses rare mixed characteristics of East Asian and Caucasian races (paternal ancestry may have European lineage).

A clear size 42 "TrekMaster" limited edition sneaker print was left at the scene.

From the murder weapon to the rope to fingerprints to blood handprints to the large pile of physical evidence he touched.

Besides that, there are several key points.

First, the perpetrator seemed exceptionally familiar with the Sato family, not only conducting long-term observation but also knowing the home environment like the back of his hand.

Second, the perpetrator's behavior was very strange; normally speaking, any perpetrator after committing a crime should leave the scene at the first opportunity, yet he not only did not leave the scene but stayed there for one to two hours, eating and drinking as if it were his own home, even taking interest in watching the family's previously recorded family gathering video — one must know that to an outsider, a family gathering video is actually a stinking long thing with no meaning whatsoever.

Finally, the perpetrator's behavior was also strange; he neither took nothing at all, nor did he act for money; he only took the 100,000-plus yen in cash stored in the drawer, while ignoring the bankbook and jewelry; and according to police verification, the perpetrator did not deliberately search — in fact there were at least two other places in the home where not a small amount of cash was stored, but the perpetrator did not search them even though he was in no hurry to leave.

As mentioned earlier, what the Japanese police excel at most is finding leads through interpersonal relationships, but investigating the Sato family's izakaya connections first was very complex — customers came and went, staff changed month by month, there was simply no accurate roster; however the Sato family's interpersonal relationships, though they occasionally had conflicts with neighbors, were relatively simple.

Grudge killing? The izakaya business indeed had minor frictions, but far from warranting family extermination; Shōta and Riko also had no abnormal interpersonal conflicts. Deep investigation of all social connections uncovered no suspect possessing motive, time, and matching the physical evidence characteristics (especially the mixed-blood DNA).

Robbery killing? Only a small amount of cash taken, other valuables untouched, does not match typical robbery-murder!

Random killing? Psychopathic killing? Mental illness killing? The perpetrator's long stay at the scene, watching the family video, eating and other strange behaviors indeed suggest possible mental illness, but such perpetrators usually have a tendency toward serial crimes; after this case, neither Toshima nor the Tokyo Metropolis saw another case with completely identical MO and target.

Contract killing is even more absurd; the perpetrator's bizarre behavior at the scene (lingering, watching video, eating) does not match a professional hitman's calm efficient style. And no evidence of any employment relationship was found. The mixed-blood DNA characteristic also increased the difficulty of random hiring.

Therefore, the Metropolitan Police discovered that no reasonable murder motive could be used to deduce this perpetrator.

Then there is the physical evidence.

This model of Trek shoes sold over 5,000 pairs across Japan; trace-back failed.

The ice pick upon investigation came from overseas, brand unknown; trace-back failed,

The dark blue waterproof nylon fabric piece after investigation may have come from a certain high-end hardshell jacket, fishing/sailing jacket, specific industry (such as transportation,

construction) work uniform, or even a custom product; the manufacturer could not provide a precise sales list.

At this point all leads left only the DNA.

However Japan only collected DNA from already convicted criminals; sample size and coverage were limited. The general population (especially those with foreign ancestry backgrounds) had not been entered on a large scale; queries via the International Criminal Police Organization to multiple national databases yielded no matches. Meaning the perpetrator himself or his known paternal male relatives (such as brothers, uncles, cousins, etc.) had not been entered into the system for other crimes.

Immediately afterward the police invested massive resources, based on the mixed-blood characteristics, focusing on screening the resident South Korean/North Korean communities in Japan (due to the shochu lead), US Forces Japan base personnel and descendants, Japanese-European/Japanese-American mixed-blood groups, etc.

Still nothing was gained.

This completely stumped the Japanese police; they had no choice but to publicly solicit leads from the whole society.

Someone claimed to have once seen a similar-looking man near the Sato residence, but could not remember what he looked like.

Someone said the Sato family extermination might be related to Aum Shinrikyo; however police investigation showed neither time nor persons matched.

Someone also said the perpetrator might be a high-IQ criminal, that the leads and behavior he left were deliberately misleading the police; but the Japanese police do not accept this — no high-IQ criminal would be stupid enough to leave his own blood, saliva, fingerprints, and DNA at the scene.

The investigation of this case instantly fell into a mystery; the whole nation heatedly discussed the matter, even drawing the Prime Minister's attention; after lasting several months, expending 55,000 man-days of police force, screening 2,200 suspicious men across the Tokyo Metropolis, no suspicious persons were found,

The Japanese police even went to the US Forces Japan bases to investigate and collect DNA, still nothing was gained; in the end that perpetrator obtained a nickname: "Ikebukuro Phantom Guest".

Now, 15 years have passed; although the Metropolitan Police has not given up investigating this case for a single day, anyone with eyes knows it is already unlikely to be solved; fifteen years on, physical evidence trace-back is almost impossible; the perpetrator evaporated from the world — may have died from injury long ago or settled overseas; key witnesses' memories are fuzzy or they have passed away; key physical evidence has already vanished; trying to investigate now, it's hard!

After this case was told, it routinely came to the interactive segment.

Promotion ceremony? Mai Xuejie felt some doubt in her heart, wondering if this case might be related to the Inner World.

"Junior Student, may I ask how you see it? Regarding this Ikebukuro Phantom Guest and the Toshima family extermination case, as the nation's Legendary Forensic Doctor, what are your thoughts?"

Uesugi Muneyuki nodded.

"Hmm, regarding this case, I believe——"