I suppose they aren't looking into the Scott Allen Kleeschulte case because they figure Devlin was too young? That boy went missing in 1988 so Devlin would have been around 20. I have no doubt he was well aware of his "proclivities" by that age.
Devlin was 22/23 when Scott came up missing and yes they are looking at that case also. It is up to each county who has a missing child to get with the other counties and the FBI. Scott was from St. Charles CO
He may have perfected the hostage, live in thing later, but as far as proclivities go, I would think pedophiles always have that urge. He could have done very bad things at a younger age.
Also we are not going to hear about everything going on behind the scenes. If there is something strong that points to Devlin being involved in the other cases then we may hear about it. But right now it is important that people investigating this keep their cards close to them. They cannot afford a mistrial due to much media coverage or someone (like his lawyers) claiming that this is turning into a witch hunt.
Devil was old enough to commit this crime in 1998! I think it is something that seriously needs to be looked into and I think Devil was involved in the missing case of Scott, and Arlin, not sure about Bianca Piper.