As part of the investigation of an offence, a non-suspect may be ordered by the Public Prosecutor to produce or hand over documents or information, if these documents have to be used as evidence before a court or to determine illegally obtained profits.
In certain cases the Public Prosecutor will need to gain the approval of the Examining Magistrate before being allowed to give the order. For different crimes/orders there are varying thresholds.
Someone who is suspected or has been accused of a crime is not obliged to produce or hand over documents in a criminal case against him/herself.