I don't know why I keep coming back to this thought, as to why Abby was redressed and Libby was left nude. But (JMO) its almost like the perp was trying to provide some sort of dignity to Abby but not to Libby. Was Libby his intended victim in the first place. Maybe I follow to many true crime shows.
RA admits that his motive was sexual assault but that he was interrupted.
IMO, he had them down the hill and still on the south side of the creek;
He had them undress under threat of a gun;
The girls are terrified and begin to strip down under his command, their clothes being discarded into a pile;
RA determines that Abby is not 'his type' thus he orders her to redress;
Abby begins redressing her terrified self, grabbing the jeans that come up first (maybe she is searching for her own clothes and he tells her to just hurry up and 'get on with it');
RA is then interrupted in his plans for SA of Libby by a white van travelling up the private drive which he confesses he sees;
RA orders the girls across the creek and they grab at whatever clothing is left in the pile to take with them because they had zero idea that their deaths would be the actual outcome of RA's sick adventure that day;
These terrified girls scramble across the creek under threat of gun by a monster that has already ordered them to strip and drop articles of clothing as they scramble ... was he telling them to "hurry up!!";
They head up the embankment on the north side of the creek and RA immediately kills Abby, probably from behind, as she is not 'his goal';
Abby falls where he kills her, the phone and Libby's shoe underneath her - never to have movement again;
Libby scrambles away from them - he no longer has control of her as she realizes is it life or death at stake - flight or freeze;
RA chases her down and repeatedly slashes at her throat as she is trying to get away;
Libby dies and RA drags her lifeless body back over to where Abby is, back to that large deadfall tree that will block their bodies from being seen from across the creek;
RA takes some time to witness his work, to toss some branches on them to hide them a little better, to perhaps look for the round he dropped;
RA leaves;
It is over.
Occam says: A kidnapping and sexual assault with an admitted purpose of r*pe, the goal of which was interrupted by a white van, and ended in their deaths.
Exactly as RA confessed to.
IMO.
#JusticeForAbby&Libby