A parent killing a child happens more often than we think

Updated 3:01 PM ET, Fri July 7, 2017

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(CNN)It's the most unfathomable of crimes: a parent killing their own child. It grabs headlines when it happens -- like this week in Georgia, where a mom is accused of stabbing four of her children to death. The reality is, filicides happen with depressing regularity in the US. And mothers are almost as likely to be the killers as fathers.

Of course we're shocked whenever we hear about a parent taking the life of their own children. Think Andrea Yates or Susan Smith. But what's even more shocking (and sad) is that this type of crime happens a lot. A study in the journal Forensic Science International looked at three decades worth of filicide cases (between 1976 and 2007) and found they occurred about 500 times a year in the US.