§1. Whenever an ordinary has knowledge, which at least seems true, of a delict, he is carefully to inquire personally or through another suitable person about the facts, circumstances, and imputability, unless such an inquiry seems entirely superfluous.
§2. Care must be taken so that the good name of anyone is not endangered from this investigation.
§3. The person who conducts the investigation has the same powers and obligations as an auditor in the process; the same person cannot act as a judge in the matter if a judicial process is initiated later.
Source: Code of Canon Law (Vatican.va)