Looks like Devlin likes em YOUNG. If you were a pedophile and they get OLDER, what do you do with the boy when he is older? A pedophile doesn't want to go to prison. So, he kills them or gets a replacement and kills the older one in front front of the replacement to terrorize them and make sure they don't try to get away or "that could happen to YOU and your family... "
That's just my guess.
That is just evil!
I did have that thought, too.