Mothers who kill their children

The disappearance of Trenton Duckett (see previous post) has had me thinking about mothers who kill their children.
What drives these women to kill?
In some instances they are genuinely psychiatrically unwell.
Take Andrea Yates for example. Andrea had five children who were all very young. With each child Andrea suffered post natal depression/psychosis and by the time the fifth child had arrived, Andrea was really not fit to be left with her children. Then one day, just after her husband went to work Andrea drowned all of her children. She believed that she was sending them to heaven. Andrea was legitimately mentally ill and should not be held solely responsible for the deaths of her children. She is about to have a second trial to determine her guilt. I hope they realise that she was unwell. This case is a tragedy in many ways and blame could be placed in many places, but that doesn't bring the five Yates children back.

There are also cases where a mother has been accused, but there is genuine doubt about her guilt.
Darlie Routier is on death row for the murder of her two sons. Darlie said that she woke one night to find a man attacking her and two of her three sons had been brutally attacked. Darlie suffered significant defense injuries and her sons had been stabbed. Darlie was arrested and found guilty of murder and sentenced to death. Evidence has since come forward that the police found a bloody fingerprint in the house which do not match anyone in the Routier family. The jury were also not shown the photo's of Darlie's defense wounds and the severity of the wounds was played down significantly by the prosecution. The jury were shown a graveside party held on the 5th birthday of one of Darlie's sons, just a few days after the murder. What the jury were not shown, on that same tape, was Darlie grieving before the party. I'm usually pretty harsh on people, but I have come to believe that Darlie is innocent. For more on Darlie click here.

Now these two cases invoke a lot of sympathy from me. The next two don't.

Susan Smith should never have had children. She is too selfish. Susan was having an affair with a man who did not want children, his or not. So rather than find someone who would accept her AND her children, or give her children to her ex-husband to raise, Susan Smith drove to a lake, got out of the car and pushed it into the lake with her two sons strapped into their seats. They didn't have a chance. She then had the nerve to go on television and claim she had been carjacked by a black man. Eventually she confessed. Some claim that Susan Smith was a failed murder-suicide. If that's the case she should finish the job.

Diane Downs is an even worse human being than Susan Smith. Her motive for killing them was the same as Smith's - they stood in the way of a potential relationship. But while Susan Smith let her children drown, in a fairly passive murder, Downs shot her three children at point blank range, and then blamed the ubiquitous bushy haired stranger. Unfortunately for Diane, she only killed one of her children. The other two were permanently disabled, but they were able to testify in court that the person who shot them was "my mommy". Diane Downs still has the nerve to claim to be innocent - she even went on Oprah from prison and claimed to be innocent. One good thing came out of this case - her surviving children were adopted by the local DA and his wife and went on to have normal lives.

These four cases are just a few mothers who have killed their children, but they show the spectrum of cases in this category. I wonder which one Melinda Duckett falls into?