As a rule of thumb: in wartime yes, in peacetime no. However i have perhaps a broader view of what constitutes “wartime”. When an imperialist power tries to sabotage or undermine a socialist state, that is an act of war. Those who do the dirty work of the imperialists - saboteurs, traitors, spies, etc. are fair game.

In general i would say the use of capital punishment should be inversely proportional to the stability of the society. In times of instability and conflict the risk posed by not executing enemies of the revolution is sometimes just too great. Of course this depends on the circumstances and the specific case.

As long as imprisonment is an option i do not believe in capital punishment for “ordinary” crimes that lack a political component, that is either a political motivation or a political impact. Because punishment is not about moral retribution, it is about protecting society. And even in the case of politically motivated crimes, re-education may be possible. If someone can be “turned” that is preferable.

When imprisonment is not possible however, such as while a revolution is ongoing and the manpower to staff the prison is not available or when there is a risk of control over the prison being lost in the course of the fighting, then yes, it probably makes more sense to execute say, a serial killer, who despite their crimes not having a political component would still pose an unacceptable threat to society if they were to escape.