Giovanni Battista Bugatti (1779–1869) was the official executioner for the Papal States from 1796 to 1865. He was the longest-serving executioner in the States and was nicknamed Mastro Titta, a Roman corruption of maestro di giustizia, or master of justice. He carried out a total of 516 executions. [1] At the age of 85, he was retired by Pope Pius IX with a monthly pension of 30 scudi." I guess that means the Popes from 1796 to 1865 were fine with the death penalty.
““It must be remembered that power was granted by God, and to avenge crime the sword was permitted; he who carries out this vengeance is God’s minister. What motive have we for condemning a practice that all hold to be permitted by God?” - Pope Innocent I
“The same divine authority that forbids the killing of a human being establishes certain exceptions, as when God authorizes killing by a general law or when He gives an explicit commission to an individual for a limited time. The agent who executes the killing does not commit homicide; he is an instrument as is the sword with which he cuts. Therefore, it is in no way contrary to the commandment, ‘Thou shalt not kill’ to wage war at God’s bidding, or for the representatives of public authority to put criminals to death, according to the law, that is, the will of the most just reason.” - Saint Augustine
“If a man is a danger to the community, threatening it with disintegration by some wrongdoing of his, then his execution for the healing and preservation of the common good is to be commended. Only the public authority, not private persons, may licitly execute malefactors by public judgment. Men shall be sentenced to death for crimes of irreparable harm or which are particularly perverted.” - Saint Thomas Aquinas
“Even when there is question of the execution of a condemned man, the State does not dispose of the individual’s right to life … by his crime, he has already dispossessed himself of his right to life.” - Pope Pius XII
“The secular power can without mortal sin carry out a sentence of death, provided it proceeds in imposing the penalty not from hatred but with judgment, not carelessly but with due solicitude.” -Pope Innocent III
"Far from being guilty of breaking this commandment [Thou shall not kill], such an execution of justice is precisely an act of obedience to it. For the purpose of the law is to protect and foster human life. This purpose is fulfilled when the legitimate authority of the State is exercised by taking the guilty lives of those who have taken innocent lives.” - Catechism of the Council of Trent