20. Every person who hinders an investigator contemplated in section 19 in the performance of his duties, misleads him or attempts to do so by means of concealment or false or untrue declarations, or refuses to comply with an order he may give, is guilty of an offence.
Such investigator shall, if requested to do so, produce a certificate attesting his quality, signed by the chairman of the Board or a person authorized by the chairman for that purpose.