Member States shall provide for the controller, where applicable and as far as possible, to make a clear distinction between personal data of different categories of data subjects, such as:

(a) persons with regard to whom there are serious grounds for believing that they have committed or are about to commit a criminal offence;

(b) persons convicted of a criminal offence;

(c) victims of a criminal offence or persons with regard to whom certain facts give rise to reasons for believing that he or she could be the victim of a criminal offence; and

(d) other parties to a criminal offence, such as persons who might be called on to testify in investigations in connection with criminal offences or subsequent criminal proceedings, persons who can provide information on criminal offences, or contacts or associates of one of the persons referred to in points (a) and (b).