@NickoD, did you see the closeup image where you can see what appears to be a gun underneath BG's jacket? If it is, that would indicate to me that he's left-handed. Many of us share your view that he had a firearm. The girls were very close friends and from what we know of the them, Libby would have tried to protect Abby. She had a much bigger build and was very sporty so obviously she would have been a lot stronger. For this reason, I think he murdered Libby first. If he did have a gun, he had total control over both of them.