These soldiers are the Army’s FBI and Secret Service
The Army has its own criminal investigation service filled with special agents that investigate major crimes, protect VIPs, and maintain criminal records.
The Criminal Investigation Command is often known as CID and its special agents carry CID badges. This is a tie to the unit's history as the command was originally formed as the Criminal Investigation Division in 1918 by the commander of the American Expeditionary Force, Gen. John "Black Jack" Pershing.
Agents from the CID go in anytime the Army is — or might have been — a party to a major crime. This includes violent crimes like murder and rape as well as white-collar infractions like computer fraud.
Approximately 2,000 soldiers are assigned to CID, 900 of which are special agents. These soldiers investigate the crime on their own or in conjunction with other law enforcement agencies. Agents can build cases, request arrest warrants, and detain suspects the same as other federal law enforcement officers.
The Army CID gives commanders an option for investigating major crimes on their installations or at deployed locations, but the agents do not fall under their installation's chain of command. The CID units report up the chain to the CIC commanding general who, in turn, reports directly to the Army Chief of Staff and the Secretary of the Army.
This allows CID agents to conduct their investigations with less fear of repercussions from senior leaders on base.
During times of war, CID can be called upon to investigate war crimes. Massacres, the use of illegal weapons like chemical and biological agents, and many crimes against humanity would fall within their purview.
But CID agents do more than just investigate crimes. The 701st Military Police Group (CID) contains the U.S. Army Protective Services Battalion. The Protective Services Battalion is tasked with guarding key Army leaders, the Secretary and Deputy Secretary of Defense, and the Joint Staff.
They also provide security for other leaders when tasked, including the senior leaders of allied militaries.
Agents for all CID positions are recruited largely from within the Army, though there is a direct accessions program that allows civilian college graduates to join.