I just thought, who could be a serial predator, know many places, live at many places, all over the country, kill several times, and none the wiser?
The former army brat.
Imagine Eric Harris graduating, being rejected by the Marines, and going the SK’s way. How would it look like?
Eric would travel to places where his dad used to be stationed, kill there, and return to Littlejohn, where he’d attend a local community college (absences easier unnoticed than in a private college). The murders would have no logical geographical connection, because who would link all these bases his dad used to be stationed at?
Also, the military are one group of people who may be not local at all and yet accepted without suspicion, because it is in the people’s mentality, thank you for your service. Furthermore, if the family moves, it, too, might be unnoticed.
So if we are thinking of a kid who attended school in Delphi (of Eric’s type, pretty and nice, but unnoticed because he was a new kid on the block), and then moved away, and was unnoticed, and whom no one can remember. I’d ask if there was an army brat attending Delphi school once upon a time. Such a person should be on the other end of the age spectrum, closer to 35. And check where he moved after that, and if there were any murders/disappearances there.
I am not a local, but just an idea.