About 18 months ago a dear friend of ours went through a relationship break up, his partner moved out and took the children, there was a lot going on, and I am sure we only knew bits of it, however he was heartbroken at losing his children, hurt and angry how he was being treated by his Ex, this we know because he told us so, he went missing for 3 days and was found hanging.
He was angry at his other half but there was no way he would kill their children to hurt her, there was no way he would hurt his children as he loved them, He was unhappy, he hurt his self and he did it once.
Sane people do not kill their children, people intent on killing them self do it the first time.
It is sad for the whole hogan family, and the child's mother will have to live with her part in what happened (and to be fair no one knows what happened if she was seeing someone, going to leave etc.)
The sister will need support and counselling for a long time to come, and a little bot has had his life stolen from him.
Personally sane or not I think he should have gone to jail, but that just my personal view.