I was thinking about how someone could obtain fingerprints and DNA of people long deceased and possibly cremated, and had a thought…

Back in the 1950s, when my childhood home was built in Minnesota, the bathroom cabinet had a slot where you could dispose of used razor blades. Everyone used those flat, double-edged blades back then, and all through the 1960s and beyond. The idea was, when the blade needed to be replaced, you’d take it out of the razor and slide it into that slot. The blade would then fall in between the studs inside the wall.

My dad died in 1970. I was thinking, if he had been cremated and if, for some reason, I needed to obtain a sample of his DNA and fingerprint/thumb print, that would be how it could be done. He would be the only person to touch his razor blades, putting them into his razor and later removing them to insert in that slot, and then they would remain in the wall, untouched and undisturbed, for decades. Significantly, they would also likely have DNA traces from whiskers, dead skin cells, and possibly blood, if he nicked himself occasionally.

Did houses and apartments in California commonly have this feature in medicine cabinets back then, too? If so, if a Z suspect lived in such a place for a length of time, he may have left forensic evidence in the walls, that may still be there……

Like an archeologist, layers of spent blades would have to be carefully analyzed, the ones on bottom of course the oldest, with markings (brand names, logos, slogans, and styles) on the blades also providing clues as to approximate age. If a guy lived there for a known period, and several blades with identical forensics from that same period could be identified, and if the gender and nationality of the DNA matched the suspect, you’d have his DNA and likely his prints. Of course, you’d have to be careful that another male friend or relative wasn’t also living there, etc. That’s why finding multiple similar exemplars would be important, to filter out the noise of occasional house guests.

Anyway, just a thought.