§ 72 BDSG
Distinction between different categories of data subjects
(1)The controller shall, where applicable and as far as possible, make a clear distinction between the personal data of different categories of data subjects, such as 1 persons with regard to whom there are serious grounds for believing that they have committed or are about to commit a criminal offence,; 2 persons convicted of a criminal offence,; 3 victims of a criminal offence or persons with regard to whom certain facts give rise to the belief that they could be the victim of a criminal offence and; 4 other parties to a criminal offence, such as persons who might be called on to testify in criminal investigations or subsequent criminal proceedings, persons who can provide information on criminal offences, or contacts and associates of one of the persons referred to in Nos. 1 and 2.