I realize I am resurrecting a very old thread here...but for some reason, I have been thinking a lot about this case lately. The more I think about it, the more I think that it was, indeed, a murder-suicide. I don't know why she made sure she killed her nieces, but I am guessing she had some real resentment (real or imagined) towards Warren. I do NOT believe he abused his daughters in any way.
Here's what swayed me:
1) After they left McDonald's. the kids were not strapped in. I don't quite understand why the older Hanse girls wouldn't have strapped themselves in, but they weren't.
2) She was not an alcoholic and she was not really even a drinker, as far as anyone knows. Sure, she could have hidden it, but when? She worked full time and then took care of kids, then took care of her husband, lather, rinse, repeat. I don't think she could have pulled it off for long. She was forcing herself to drink to get up the courage to do what she did.
3) She hung up on her brother and left the phone intentionally on the side of the road.
4) If she didn't intentionally kill the nieces, then something happened that morning at the campground. She likely had been thinking about it for awhile, but then decided THAT DAY was the day, and Kate, Alyson and Emma were just collateral damage.
Anyway, just wanted to say all of that!