Priests do not report crimes confessed to them to the relevant authorities.

Just to avoid any misunderstanding, it has to be a sacramental confession for the 'seal' to apply. The priest must be wearing the stole and the admission must be for the specific purpose of obtaining absolution, which the priest might, at his discretion, withhold or make conditional.

In the latter case, the condition could be that the penitent turn him/herself in to the authorities and confess the crime.