http://heroismedievais.blogspot.com.br/2011/05/sao-bernardo-eu-vou-executar-esse.html

I found it in the blog Heróis medievais (medieval heroes).

St. Bernard: “I’m going to dispatch (to execute) this criminal with my own hands!”

One day when St. Bernard headed to the court of Count Theobald, a group of soldiers who were conducting a prisoner to the gallows to hang him encountered the Saint [St. Bernard].

Seeing the scene, S. Bernard seized the rope that the condemned was conducted with, and made this strange (weird) proposal to the executioners:

– Deliver me this criminal, and I will execute (dispatch) him with my own hands.

At that time, the count approached. His astonishment was profound to see the Saint, who he estimated as he was his father , between the killer and the officers of justice. He was stunned to hear the petition of his friend [that is, St. Bernard]:

– Venerable father, what does this mean? Why do you intend to save the life of a murderer who deserves death hundreds of times? It is an incorrigible son of Satan, and the best service we can render to him is to deprive him of life. The interests of society require his death.

– I know that this man is worthy of death, and I do not intend to let him go unpunished. Rather, I want to subject him to harsh and perpetual punishment. You would hand him on the scaffold, where soon he would escape to your power, but I will bind him at a cross, where he will suffer many years.

Theobald having not formulated objections, Bernardo put his hood on the wrongdoer, whom he named Constantine, taking him to the convent.

After thirty years of severe penance, the blessed Constantine died, his feast day is March 16.

(Source: Ailbe Luddy, “Bernard of Clairvaux”)