Pre-arrest Investigation:

Pre-arrest investigation is the stage of criminal procedure that takes place after a report of suspected criminal activity or law enforcement otherwise becomes aware of such activity, but before an arrest is made. Law enforcement investigates whether a crime has occurred and whether an arrest should be made. If law enforcement determines that the evidence uncovered during pre-arrest investigation reveals that a crime was committed and a suspect is identified, law enforcement may arrest the suspect or, depending upon the jurisdiction, present the investigation results to the prosecuting attorney.

 If the jurisdiction is one in which the prosecuting attorney becomes involved pre-arrest, the prosecuting attorney generally decides whether and what charges to file; only after such determination does an arrest take place. Alternatively, after an investigation, law enforcement may determine that there is insufficient evidence to pursue the matter, and no arrest is made.