I wonder if the "investigators" were subconsciously not that interested in actually solving the mystery, but were just enjoying the process. Can't remember what it was I was reading recently, but there was a character who deliberately did things the hard way, or in a convoluted way, because it satisfied something inside of him.

Edit: It was this article about an orchid collector: https://www.susanorlean.com/articles/orchid_fever.html