I really don’t think having knowledge about DNA in 2017 is that unusual. I think I first heard about DNA during the OJ Simpson trial in 1994. IMO
(Too bad you were not in the jury; for many people, the importance of DNA evidence was lost in OJ case)).
And even after 1994, lots of criminals left their DNA on the crime scenes… OJ’s case showed only that if you are a murder suspect, and there were no witnesses, you still might be matched to your crime scene by your DNA (left in abundance).
However, it didn’t resolve the issue of “stranger’s” DNA on the CS. Basically, serial killers. This was a different phase. Such broad genetic criminology became possible with the development of huge, open-source genetic databanks, such as Gedmatch. Really, GSK was one of the first published cases. GSK’s arrest in 2018 became possible because the amount of people submitting their DNAs to Gedmatch reached a certain statistical level. (And maybe, also, because many linked their family trees to DNAs).
GSK case amply demonstrated how even foreign, unknown, DNA left at the CS might be identified.
However, the Delphi situation, when allegedly, the girls were killed exactly where they were found, in less than 30 minutes, plus, the CS, as we are led to believe, was something unbelievable, plus, the killer arranged it all in the same 30 min and left unseen, plus, for the whole evening and night no one, looking for the girls, getting on the bridge, noticed anything, and in the next day, suddenly someone saw the bodies through the binoculars. And, the murderer had enough time to either get rid of the DNA, or, he simply didn’t leave it.
It feels strange. And to add to it, the police has the video and the voice, but the video was not released till 2019…and the voice, as DC says, belongs to “the devil”.
When we start reading about new cases, we never can, mentally, reconstruct them, because the police (and for a good reason) doesn’t tell the whole story. (I remember KB’s murder, when her poor mother, perfectly understanding who was the culprit, said “they are good, they are loving”, only to give the police enough time to work with the case. Reality is shocking…to think that another woman could stupidly agree to clean after a killer surpasses any detective novel. But… the criminals were regular rural dwellers, getting rid of the body but leaving electronic trace. That fits. Not so in Delphi case.).
So I think that perhaps, in Delphi case, the reality will be somewhat unexpected as well, and perhaps the case is multi-layered. But as long as the girls were not alone on that bridge, that CS, even if the narrative is very different from what we know … we don’t need to know everything. But whoever killed them needs to be punished.