I think he sold her to South American human traffickers.
In any event, it will be very interesting to learn if the Peruvian interrogators learn anything new & important about NH and/or other young women he's beaten or killed.
***I don’t think that he beat NH to death on the beach, simply because I believe that it would have been impossible to hide all traces of blood and/or DNA evidence.***
Also: if she was buried in the marshes or at sea - her clothing, shoes etc., should have washed up somewhere (unless Daddy burned them).