[2][3] Quigley enlisted in the United States Army in 1989, becoming a military policeman after a short time as a foot soldier.

While serving in Iraq, during Operation Enduring Freedom, Quigley left the Army and accepted a direct commission into the United States Navy Reserve in August 2003.

[4] Following his deployment in Iraq Quigley accepted a job as a civilian counter-terrorism analyst at the Defense Intelligence Agency.

Quigley was part of a team assigned to interrogate the "high-value detainees" at Guantanamo, including Abd'l Hadi al-Iraqi, a senior leader of al-Qaeda, and formerly a captive held by the CIA.

[6] Quigley is a member of the Baker Street Irregulars literary society dedicated to the study of Sherlock Holmes, Dr. Watson, Sir Arthur Conan Doyle, and the Victorian world.