If this is true he killed the girls first. He needed to make sure he knew exactly when she got home and that NU didn't try to come in either. I was leaning more towards that they got into a fight and he killed her in a rage and then killed the girls but with this piece of information I think he killed the girls first.I don't recall where I saw it or read it but it was something along the lines the door was locked to where SW couldn't get into the house without calling CW to let her in. If the master bedroom is upstairs I believe he killed her right away so that he wouldn't have to move her body to far. JMO of course I could be way off