Will is right in my opinion that unfortunately there are,and always will be, some evil people about who don't care what they inflict on others.If we knew the answer I am sure we would be using the solution by now. There is an element of personal decision making for us all such as ,for example, if you know you can lose your temper when you are drunk giving up alcohol if you can't control it.Walking away from heated situations too . However sometimes there is little you can do to preventing people who are just plain evil doing something whatever attempts are made to mitigate the risks.We just have to hope that it doesn't happen to our loved ones. However I expect life to mean life for people who are capable of such evil crimes.