The Neck Verse

During the 17th and early early 18th centuries there was a way for murderers to cheat death with what became known as the 'Neck Verse'. If murderers could prove that they had been ordained as priests, then they could not be sent for trial in the secular courts and were set free. It was then possible for the murderer to be sent for trial in an ecclesiastical court.
In medieval times all that was required to prove ordination was to prove literacy, and all that was required to prove literacy was to read, write or recite one verse of Psalm 51v1. Many murderers learnt the verse by heart to save their necks, before the ecclesiastical court:

Psalm 51v1

Have mercy on me, O God,
According to your unfailing love;
According to your great compassion
Blot out my transgressions.
Wash away all my iniquity
And cleanse me from my sin.