One thing I didn't think of until now is that he may have used the boxcutter as another means of control, without necessarily planning for it to become the murder weapon. A blade to my BF's neck would be a compelling, terrifying deterrent. It was also a dynamic situation, as evidenced by the sudden, new variable -- the van. RA could have forced AW to undress, then redress, telling them he'd let them go if they cooperated. And now holding a blade to one neck, the scene could have shifted. Either girl moves, control collapses and he slices. Reactive. Even to him, who started this awful series of awful events, it had to be as if out of a horror movie, one victim spiraling while losing blood under pressure.
One of RA's confessions -- that only the murderer would know -- gets lost in all this.
That the girls didn't die immediately.
Only someone who was THERE (or an MD who knows the nature of the wounds and the process of death by exsanguination). RA said he didn't want them to suffer. I dont believe he was suddenly compassionate or magnanimous, but I do believe he saw firsthand that their deaths were not immediate. And he waited there. To make sure they were dead. All the way dead. Until their suffering was over.
You'd have had to be there to know that.
JMO