Yes, any priest would report someone who told them they murdered someone. But if the murder was part of a confession, no. I imagine part of the penance would telling someone to confess.
Absolution is not free. It is dependent upon the acts taken in repentance. False confessions, i.e. no intention to repent or refusal to undertake contrition, does nothing to help the confessor in the eyes of God.
In other words, going through the motions while lying to God doesn’t work.
Turning yourself in to the appropriate authorities is a perfectly fine, and I’d wager universally given, admonition by a priest to a confessor of crime - especially crimes against the person.