It's a strange phenomenon that seems to be occurring more and more often... a parent murders their kid(s) in order to seek revenge on their ex, and other parent of the kid(s).

Prosecutors in this particular case say that it was the need for revenge against his ex wife who he was sure was seeing someone else, and not mental illness, that drove Aaron Schaffhausen to slash the throats of his 3 daughters - 11-year-old Amara, 8-year-old Sophie and 5-year-old Cecilia on July 10 in River Falls.  ( Another case pops to mind...a man vanished with his sons over thanksgiving weekend a couple of years ago.  While he has been found, and arrested for their disappearences, he has repeatedly refuse to reveal what happened to the boys.  His motive was to hurt his ex wife, the mother of his children.)

I don't understand how mental illness could not play at least some part in situations like this... where an otherwise decent, loving parent snaps, kills their children, because they are so determined to hurt their ex. 

Regardless, another mother is left devestated and heartbroken, with scars she'll carry for the rest of her life, and 3 innocent little girls are casualties of war between their parents.  Where will it end?

http://abcnews.go.com/US/wireStory/lawyer-schaffhausen-erratic-killing-girls-18862784