LilBabyWithTheSundressOn wrote:
If it was Terry, though, I don't really understand it. It seems like he did it because he's a violent asshole, was mad at Pam, and jealous of the attention she gave Stevie. But why then did he kill all three, why did he tie them up that way, and why did he strip them naked and hide their clothes in the mud?

I think he is damn lucky they didn't have much DNA testing back then.  I think he killed the other three because they were there. I think he undressed them and tried to cover it up so that someone else, like the three boys, would get blamed for it.