Capital punishment should be applied when there's no doubt whatsoever about guilt.
For example when a criminal is caught killing someone in presence of many people and arrested on the spot.
Or when there are already strong evidence and they immediately admit the crime.
Capital punishment only when there's 100% certainty of guilt.
I believe the 3 shyts have proudly admitted their crime, so off to the beating by the old man family if they wish and if they survive give them 10 years hard labour, permanently chained up, without any parole, no tv, no playstation, a few potatoes a day and a chicken leg once a month.