I believe people need to get a chance to change themselves and even mentally challenged person should get medical help to recover.
And prison are not a great way to make them better person and is very costly.
I believe prisoners should be indulged to labour works and social works under proper supervision.
The death penalty is a relic of the past which can be replaced with better alternatives. There is simply no use for it in the 21st century , from both a monetary and humane point of view.