Local prosecution offices, such as county district attorney’s offices, and national law enforcement bureaus, including the FBI, have recently conducted several high-profile investigations of municipal, national and corporate wrongdoing. Although these investigations can be routine for those involved, the media often portray them in dramatic and theatrical terms. To de-dramatize the subject and make the process more accessible, I offer a primer on how law enforcement conducts these investigations based on my front-row seat to these events from the last 30 years of practice.

Law enforcement agencies, such as local police, the FBI, the Securities and Enforcement Commission (SEC), are authorized to investigate individual and organizational violations of law. Officers are tasked with enforcing the codes and statutes that prohibit or require certain actions. Therefore, they are allowed to make an arrest when the officer has probable cause to believe that a statute has been violated and the person to be arrested was responsible for that violation—whether as a principal, or as an accomplice, a conspirator, a facilitator, or one who solicits another to commit the offense. The information the arresting officer relies upon can be supplied by a fellow officer, by a known source of information, or by the officer’s own senses of observation. Sometimes an arrest is based upon an arrest warrant, signed by a judge in the jurisdiction where the person to be arrested is located.