Or should we only punish the accused for the crimes they intended and actively carried out?

Should we punish an accomplice in a crime that only intended and engaged in a minor crime (e.g. being the lookout in a burglary of an empty house) for all the crimes of his/her partner (e.g. the one that went in the house rapes and kills a person he finds inside without any knowledge or input from the lookout)?

Or should we only punish the accused for the crimes they intended and actively carried out?

The law today is that if you are robbing a bank and all had agreed that no one would get hurt and the guns were fake, but your partner takes out a real gun and kills three people in cold blood you will be charged with all three murders under the accomplice liability rule.