I believe it was the father who found and also moved the body.
Actually to me, just speculating, it sounds as if it could have been a friend or relative. I realize they probably exhausted those leads (one would assume), but several things make me think that. 2 forms fatal-type injuries (fracture & garrote), molestation/assault, and a rambling note that at the same time shows familiarity but tries to sound like international intrigue. To me that points to someone (who at least felt) familiar with the family, and who was a pedophile.
I also find Karr's statements interesting, "I was there it was an accident" "I love her". As a pedophile obsessed with the case (I think he fantasized being the killer) his comments provide the sicko point of view.
Karr just figured out a way to get a free ride back to the US. He's still sick in the mind, tho...........