Does the same requirement hold for those wanting to punish murderers?
That's a great question. PLEASE FORGIVE ME for a slightly
Long-ish post 
The contemporary Catholic position would be
yes, capital punishment for murderers or anyone (however guilty of crime) is inadmissible. Pope Francis has reaffirmed that
“today capital punishment is unacceptable, however serious the condemned’s crime may have been.” (Francis,
Letter to the President of the International Commission Against the Death Penalty (20 March 2015):
L’Osservatore Romano (20-21 March 2015), 7.)
See this extended commentary penned by the Congregation for the Doctrine of the Faith:
Letter to the Bishops regarding the new revision of number 2267 of the Catechism of the Catholic Church on the death penalty, from the Congregation for the Doctrine of the Faith
In the early church, this seemed to be the stance as well. Around A.D. 177, the church father St. Athenagoras of Athens wrote a defense of Christianity in which he stated that Christians not only are forbidden to kill anyone for any reason but “
cannot endure even to see a man put to death, though justly. … We, deeming that to see a man put to death is much the same as killing him, have abjured such spectacles. How, then, when we do not even look on, lest we should contract guilt and pollution, can we put a man to death?” (Athenagoras Presbeia, A Plea for the Christians, ANF). He referred to the human being as a "
sacred animal" that could not be subject to death.
But things changed after the Constantinian shift in the fourth century. The Roman Empire's legal system made frequent and widespread use of capital punishment, and if Christianity was to be an appropriate religion for imperial rule, it couldn't restrict emperors from exercising the death penalty over recalcitrant subjects. So the Church came to be more and more 'lenient', even complicit, in permitting secular authorities to execute subjects.
The earlier "anti-capital punishment stance", nevertheless lasted as late as Pope St. Nicholas the Great condemnnation of the death penalty in 866 (Letter 99):
http://www.pravoslavieto.com/history/09/866_responce_pope_Nicholas_I.htm 2
Chapter XXV.
You claim that it is part of the custom of your country that guards always stand on the alert between your country and the boundaries of others; and if a slave or freeman [manages to] flee somehow through this watch, the guards are killed without hesitation because of this. Now then, you are asking us, what we think about this practice.
Nevertheless, far be it from your minds that you, who have acknowledged so pious a God and Lord, now judge so harshly, especially since it is more fitting that, just as hitherto you put people to death with ease, so from now on you should lead those whom you can not to death but to life. For the blessed apostle Paul, who was initially an abusive persecutor and breathed threats and slaughter against the disciples of the Lord,[cf. Acts 9:1] later sought mercy and, converted by a divine revelation, not only did not impose the death penalty on anyone but also wished to be anathema for the brethren [cf. Rom. 9:3] and was prepared to spend and be spent most willingly for the souls of the faithful.[cf. II Cor. 12:15]
In the same way, after you have been called by the election of God and illuminated by his light, you should no longer desire deaths but should without hesitation recall everyone to the life of the body as well as the soul, when any opportunity is found. [cf. Rom. 7:6] And just as Christ led you back from the eternal death in which you were gripped, to eternal life, so you yourself should attempt to save not only the innocent, but also the guilty from the end of death, according to the saying of the most wise Solomon: Save those, who are led to death; and do not cease freeing those who are brought to their destruction. [Prov. 24:11]
Prior to him, so had Pope St. Gregory the Great (590-604) when he stated: “
Since I fear God, I shrink from having anything whatsoever to do with the death of anyone”.
The church’s teaching on the matter today is more reflective of these earlier opinions.
Initially, the church forbade the execution of heretics - treating heresy and apostasy as purely penitential under ecclesiastical censure.
To provide you with an example, in 350 the first execution for heresy took place (it was orchestrated by secular authorities) but the decision to execute the person was vehemently opposed by the Catholic Church, by the Pope, St Ambrose and St Martin of Tours. Most theologians saw punishment for 'heresy' as therapeutic not punitive - Christians believed that you could not force somebody to change their mind. God had given them freewill after all. To elucidate the viewpoint of this period, St. John Chrysostom (died AD 407) one of the greatest of the Church Fathers wrote, "
To kill a heretic is to introduce upon earth an inexpiable crime".
"Men ought not to be compelled to believe, because God will have mercy on those whom he will have mercy. As man fell by his own free will in listening to the wiles of the serpent, so man can only be converted by his free acceptance of the Christian faith"
- (Fourth Council of Toledo, 633)
"...Faith should be a matter of persuasion, not of imposition..."
- (Saint Bernard of Clairvaux, 1090 –1153)
Later on, Waso, the Bishop of Liege urged against using force upon the Carthari, arguing much as St. John Chrysostom had seven centuries earlier. Peter Cantor, the most learned man of this age, expressed the prevailing sentiment within the Church leadership: “
Whether they be convicted of error, or freely confess their guilt, Catharists [apostates] are not to be put to death, at least not when they refrain from armed assaults upon the Church. For although the Apostle said, ‘A man that is a heretic after the third admonition, avoid,’ he certainly did not say, ‘Kill him.’ Throw them into prison, if you will, but do not put them to death’” (De investigatione Antichrist 3:42). St. Bernard put down the law, in direct opposition to the mobs, “Fides suadenda, non imponenda.” Men are to be won to the Faith, not by violence, but by persuasion. He censured the princes, arguing that “the obstinate were to be excommunicated and if necessary, kept in confinement for the safety of others” (O’Brien, p. 15). The views of Peter Cantor and St. Bernard were ratified by a whole series of synods during that time: Rheims (1049) under Leo IX, Tolouse (1119) under Callistus II, and the Lateran Council of 1139.
But, then, in the high middle ages the church started to send more and more heretics over to secular authorities where they were executed, and Thomas Aquinas even penned a defense of capital punishment for heretics.
Throughout the middle ages, however, even if the power to condemn criminals to death was conceded to the secular power, the clergy - held to a higher standard - were expressly forbidden from having anything to do with the shedding of human blood.
The canons of the Council of Toledo (675 A.D.) stated:
It is not licit for those by whom the sacraments of the Lord are to be performed to carry out a judgment of blood. But if anyone, unmindful of these precepts, has done anything of the sort to members of his church or to any other persons, he is to be deprived of the honor and place of his granted order.
Master Thomas of Chobham, for instance, in his Summa confessorum (c. 1216), warned against the sentencing of men to death or mutilation by clerics, urging that ‘
So great is the dread of human blood that even a judge who justly slays the wicked, if he enters the religious life or wishes to be made a cleric, cannot be promoted to holy orders.’
Clerics were also prohibited from engaging in violence in the Fourth Lateran Council (1215):
No cleric may decree or pronounce a sentence involving the shedding of blood, or carry out a punishment involving the same, or be present when such punishment is carried out. A cleric may not write or dictate letters which require punishments involving the shedding of blood.
Saint Agobard (799-840), archbishop of Lyons, once stated that: “
Whoever spills human blood, His (God’s) blood is spilled as well: For man is made in the image of God”.
If we hold our priests and religious to this ideal of not “polluting” themselves with the shedding of blood through capital punishment, should we not aspire to this same degree of holiness for all including the laity as the highest aim? And is really right for the church to say, "we don't condemn anyone to death, our hands are clean", but then pass people off to a secular court where the certain judgement will be death? This "
double-standard" was often viewed as a ridiculous attempt to circumvent the non-violence of the gospels.
Since Vatican II “
clericalism”, by which the religious are held to higher standards than the laity, has been abandoned in favour of the “
universal call to holiness” and so the clerical restrictions are increasingly being expected of the secular laity as well, as reflected in the stance against capital punishment.
FYI: for more on the clerical ban and double-standard see:
Innocent Civilians
The ban on clerical fighting was part of a general prohibition on the clerical use of weapons which extended to hunting as well as warfare. Clerics could not shed blood, either human or animal. The ban on clerical participation in war was not simply an implication of the advice to those who served God not to be concerned with the things of the world. Rather, it was the act of killing which was thought to sully (as the ban on clerical hunting clearly shows). The ban on clerical participation is an acknowledgement that the most Christian thing to do is forgo all killing.
The established reasoning was to be based on the idea of the two levels of Christian vocation put forward by Eusebius of Caesaria. Eusebius held that Christians of the higher level (the clergy and religious) were to aim at the highest Christian ideals; they were bound by the ‘counsels of perfection’…This differentiation between lay and clerical morality is not firmly grounded and there is certainly no biblical basis for it.
It is odd to interpret Jesus’s command of non-resistance strictly for those Christians who desired to attain perfection (equated with clerics)…That something is not to be done by the most perfect Christians, because they are the most perfect Christians, is almost an acknowledgement that it ought not to be done by any Christian
