I used to be all for the death penalty for certain crimes. Still am. Except for the possibility of executing the wrong person. Or a mentally defective one.
Google Timothy John Evans and see how this case went a long way towards abolishing the death penalty in the U.K. Or 19 year old Derek Bentley whose 16 year old friend pulled the trigger killing a policeman. What did did Bentley mean when he said "Let him have it, Chris?" Did he mean hand over the gun or to shoot him?
I'm happy with life imprisonment meaning life imprisonment. (not 10/15/20 years)
Just maybe if the murderer is aged 18-21 then start looking at parole after 20/25 years or if older after 30 years. With life imprisonment, if forensics or other things prove innocence then there is a chance of putting the matter right.