We struggle with this case, but I am told that perhaps half of murders go unsolved. In fact, there is such a thing as a misdemeanor murder, a case so old and lacking in evidence that it is useless to keep it active. I do not think the DP9 were murdered, far from it, but a break in a cold case seems to come from using improved technology with old clues. Agaun, Teddy et.al. are using forensic methods not employed in 1959. This is to her credit.
An identified fault in trying to solve mysteries is one of forming a hypothesis too soon and force fitting facts to it ( eg. I know he did the crime and now I will prove it). The other approach is to gather the evidence and then generate an hypothesize. You, Ziljoe, are astute in your open minded and even handed assessment of the evidence, but I think we agree that unless there is a breakthrough owing to discovery or refined technology, the investigation stalls out just like many, many unsolved mysteries.
At the heart of it is the issue of why they left the tent. Can technology ever address that question? No, we just need a better way of inspecting the bread crumbs the case gives us.