Oddly (I'm wondering myself), I often think of a non-sexual offense in Delphi, more of something like contempt, humiliation, punishment, even hate of young females.
If I let wander my thoughts, there is a story. Maybe, my imagination could be less special; sorry for that in advance.
We spoke of truck drivers already ...
Father is a truck driver, has his job during childhood of his son. (Long haul) truck drivers are known for taking girls/woman on board for entertainment and because of boredom, not least because of the opportunity. Of course, not all truck drivers do this - noone here needs to defend the poor truck drivers; I know it: certainly there are many exceptions. My version of truck driver enjoys his trucking life in one or the other way.
Mother is sitting at home through these same years, feels overwhelmed by some children and cheated on by her trucker husband. Son is very sensitive and is suffering from the situation during the years.
When the son is grown to a teenager, his trucker father thinks, he has to make a tough man out of his son. Insensitive Macho, who he is, father proudly tells his son, in which way he himself had/has fun, when he was/is driving across country: taking teenagers (maybe run-aways) or in general young females with him into "nature" (parks, trails, lakes, creeks, bridges, truck stops).
One special day in his life this son needs a valve for his feelings for more than one single reason and starts to "avenge his mother" in an evil, angry way, feeling very relieved afterwards. Because the valve worked so well, the son compulsively has to do it once more, when times are rough for him, and once more .... , becoming well-known, notorious BG one day in 2017.
IMAGINATION only and spekulation, looking for the motive and looking for a non-sexual killing. May well be 100% ERROR on my part.