This is all something I feel personally inclined to believe, that he knew these people and the TMPD have just not revealed it for whatever reason or haven't followed up on it hard enough.
RSBM
I do believe the culprit knew
of the family, I am not totally convinced they knew him and a connection has just been missed at this stage. But there are certainly things the TMPD
do know about him that they have not revealed. That is a fact.
Recently in an article a neighbour said that he had seen the bathroom window was often left open for ventilation purposes. That is one person who noticed the pattern of the window being left open.
So who else did? Did the skaters who occupied the park daily across the street? Likely. Did the university students in the dormitories by the baseball field? Dog walkers? Families using the kid’s park? Regular tennis players in the courts? A passer by on more than one occasion?
This little factoid opens up the possible culprit to a person who just noticed that window being open and watched the house a few times, then decided to come back to kill them.
This brings me back to a something I've always suspected before, in that there was info in this case about the condition of the bodies of the family members were left in when Haruko discovered them. As we know, Haruko came across the body of Mikio first and it's said that a drawer was placed on Mikio's body. Then came the bodies of Yasuko & the girl Nina, Haruko said that Yasuko's entire body was covered in a pile of clothes and couldn't be distinguished by her at first and then Nina's body was facing downwards with her face also pointing down. The boy Rei's body was left lying face down on the bottom bunkbed with a futon mattress covering his head.
RSBM
Tsuchida-san has been quite descriptive about the state the bodies were left in. He describes the wounds as more of a cutting motion than stabbing, like he was trying to carve them up before killing them. The sheer amount of blood in the loft and that Yasuko and Niina made it down the ladder and didn’t die up there, for example, indicates this.
About the faces being covered, what you say could be true and they were all deliberately covered in some way. But after seeing the photos myself the house was in such huge disarray it almost looked like an explosion had happened.
Around Yasuko and Niina, for example, a blanket was hanging down from the loft and next to them were several pairs of shoes, slippers, clothes hangers, bags, more blankets, etc. Rei’s pillows had been thrown across the room, his bedroom drawers opened. It appears that in the struggle things had been thrown, dropped, and landed all over the place. I couldn’t say whether this is why or if their faces were deliberately covered, but it’s also potentially just that things landed that way.
250,000 investigators working on the case at one point or another is so mind-boggling ... still shocked they could never find any certain leads.
It's a shame their DNA databases weren't widespread at the time, and still have privacy and testing limitations... I feel like they'd get a hit if they could run it against other countries' databases, or if genealogical testing wasn't disallowed.
The DNA is the key.
Unless there is some kind of breakthrough like in the Takaba case. But even then, the culprit handed herself in to the police.
