I was watching "Most Evil" on my DVR, and (how appropriate!) the topic was about people that scheme and lie.
It opened with the story of Diane Downs.. on May 19, 1983, she shot all three of her children and created superficial wounds on herself to pin it on an imaginary hitchhiker.
At the hospital when one of the kids died, she showed little to no emotion. When she found out the other two would live, she was stunned. From the article: "When told that Danny had a chance of surviving, she replied in an almost-perplexed manner, "Do you mean the bullet missed his heart? Gee whiz!""
There are some parts of the case that aren't remotely like this one (people actually believed Diane Downs at the start, even though law enforcement was suspicious -- the media made Diane look like a hero). However, the motive is what scares me the most. Because of a man that Diane wanted to be with had shunned her and she blamed having three kids for it, that's what drove her to commit such a heinous crime. She thought she could garner sympathy if all three died and he would have no choice but to be with her.
The article is a fascinating read:
http://www.trutv.com/library/crime/notorious_murders/famous/downs/1b.html
Anyway, not saying these cases are exactly alike (no two are), but as an observation as I was reading it I could see how some things applied to this case.