The executive agency that would most likely investigate cases of espionage is the Central Intelligence Agency.
The Central Intelligence Agency was formed in 1947 in the United States and its aim has always been to protect America's national security in a post-Cold War world. The CIA mainly uses human intelligence to gather and examine security data. However, the agency sometimes resorts to the use of high-technology for intelligence purposes. Nowadays, the CIA is also in charge of studying paramilitary operations and fighting against cyber-espionage.
