I think what this issue boils down to is the question of how to minimize the total number of deaths. Obviously a repressive regime that enforces a death penalty for numerous crimes will cause many unnecessary deaths. The hard question is whether you are better off applying the death penalty to a small number of particularly serious offenses, or to none at all.
I think there is a case to be made for executing criminals who are guilty of murder, especially those who have been convicted of multiple offenses. Justifying execution for any other offense is much more difficult.