Part Three. Court Proceedings
Section IX. Proceedings in a Court of the First Instance
Chapter 37. Judicial Investigation
Article 278. Interrogation of Witnesses
5. If it is necessary to provide for the security of the witness, of his close relatives, relations and near persons, the court shall have the right to conduct his interrogation without making public the genuine data of the witness's person under the conditions, precluding a visual observation of the witness by the other participants in the judicial proceedings, on which the court shall pass a ruling or a resolution.
National judicial procedures protecting witnesses from identification – witness protection
EDIT.