So much so that if a penitent came and confessed that he was a serial killer who had murdered 100 people, and the confessor judged him likely to murder more, he could not report the man to the authorities.
I'm trying to jog my memory, but I recall recently seeing a story where some "confessor" ratted out a penitent and had him arrested for some crime.
In the 1953 Alfred Hitchcock
movie I Confess, Montgomery Clift plays a
priest who refuses to break the
secrecy of the
confessional, at great personal cost to himself.