prevention is far more effective and cheaper than imprisonment. so much more needs to be done in that respect.
as consequences go your scenario is extreme so extreme measures might be required.... it dopes depend on intention and motivation. deliberate murder at a young age is a prime indicator of adult behaviour. not much can be done to treat such people.
Pete I suggest you do a scan for genuine research into such scenarios. you call my thoughts a "social experiment" as in a disparaging manner. but social programs are necessary to help society/community to move forward and develop better ways of addressing problems.