As he said in one of his confessions, when he saw the van, he knew his plans were ruined. After that he never really mentions the girls. He just said they went across the creek and he "cut the necks" because he didn't want witnesses. He completely depersonalized the girls, didn't even think of them as human, as most sociopaths, killers and pederasts do. The girls exist only for his sexual gratification, their lives were meaningless to him. They still are meaningless to him. He's not sorry for killing them. He doesn't care, isn't capable of caring.
BTW, I hope we soon get to hear the recordings of his voice on the phone calls or any recording of it at all.