The officers and agents of the judicial police ensure that the state of the scene is preserved and that traces and evidence are preserved until the technical and forensic operations are carried out. Unless the magistrate designates a specific technical and forensic police service, these operations are carried out by the specialists usually called in by the first responders.
When it is necessary to carry out technical or scientific examinations that cannot be postponed, criminal investigation officers may, depending on the type of investigation they are conducting, call upon qualified persons belonging to the specialised bodies of the national police or the national gendarmerie.
The interpretation of the results of technical and forensic police operations may be entrusted indiscriminately to the specialised bodies mentioned above. They pool the resources at their disposal when their own capabilities prove insufficient.