Dad's Strange Behavior Unsettled Some Before Child's Killing

http://www.nbcnews.com/news/us-news/dads-strange-behavior-unsettled-some-childs-killing-n282581

A father in Florida was arrested for throwing his 5 year old daughter off the side of a bridge and killing her.  They haven't been able to tell whether the daughter was dead before her father threw her off the bridge or not.  There were also some reports of the father acting very strange before the incident.  There were a couple of occasions where he was reported talking very strangely and angrily, but he had never been diagnosed with any mental illness before this.

He was offered a attorney, but he declined and said he wanted to leave it in the hands of God.  The police said that acting crazy isn't enough for them to come in and commit somebody.  This is a very sad incident that occurred and I it seems like they are happening more and more lately.  I don't know if it is just me or if more and more people are committing these types of crimes more.  I wonder what leads to people doing this and how could we start to prevent these types of things happening in the future.