The John Paul II argued that in a "culture of death" it was morally contradictory to execute murders was because the murder of children in their mother's wombs was sanctioned. However, he never claimed capital punishment was "against the Gospel", which it demonstrably isn't, and, therefore, intrinsically evil. He recognised it was a matter for the prudential judgement of civil authority. John Paul thought that capital punishment was in practice best avoided but this was a non-binding prudential judgment.

Pope Francis cannot  reverse Scripture or his predecessors on such a matters. He is bound to binding interpretations. There a mountain of evidence from Scripture, the Fathers and Doctors of the Church, Popes, Saints and theologians, and Catechisms and other Church documents, that shows conclusively the legitimacy of capital punishment. 

And since you ask, I am against personally against the death penalty for the reasons given by John Paul and not Pope Francis.