Question: Omar Aquino served as an aide under which retired U.S. Army Lieutenant Colonel, now Congresswoman?
Context: Carlo D'Este (born 1938 in Oakland, California) is an American military historian and biographer, author of several books, especially on World War II.  He is a retired U.S. Army lieutenant colonel who has been awarded the Legion of Merit, Bronze Star with Oak Leaf cluster, Meritorious Service Medal and Commendation Medal. A Bright Shining Lie: John Paul Vann and America in Vietnam (1988) is a book by Neil Sheehan, a former "New York Times" reporter, about retired U.S. Army Lieutenant Colonel John Paul Vann and the United States' involvement in the Vietnam War. James B. Channon died on Sunday, September 10th, 2017, at his home in Hawaii.  James B. Channon is a retired U.S. Army lieutenant colonel, New Age futurologist, and business consultant.  He is primarily known for authoring the "First Earth Battalion Operations Manual" (1979, and later editions), a popular book pointing the way toward a New Age transformation in the U.S. military.  Heavy on graphics, it was partly inspired by the "Whole Earth Catalog" counterculture magazine. Lones W. Wigger, Jr. (born August 25, 1937) is a retired U.S. Army lieutenant colonel.  Wigger was member of the United States Olympic team on three occasions, and two time Olympic Gold Medalist. Ladda Tammy Duckworth (born March 12, 1968) is an American politician and retired U.S. Army Lieutenant Colonel, serving as the junior United States Senator for Illinois since 2017.  A member of the Democratic Party, she earlier represented Illinois' 8th district for two terms (2013–2017) in the United States House of Representatives.  Before seeking elective office, she served as Assistant Secretary for Public and Intergovernmental Affairs in the United States Department of Veterans Affairs (2009-2011), and she was the Director of the Illinois Department of Veterans Affairs (2006-2009).  In the 2016 election, Duckworth defeated incumbent Republican Senator Mark Kirk for the seat in the United States Senate. Michael Lee Lanning (born September 18, 1946) is a retired U.S. Army lieutenant colonel and the author of military non-fiction. Anthony Ray Jones is a retired U.S. Army Lieutenant General who served as acting commander of the U.S. Army Training and Doctrine Command. Allen Bernard West (born February 7, 1961) is an American political commentator, retired U.S. Army Lieutenant Colonel, and former member of the U.S. House of Representatives.  A member of the Republican Party, West represented Florida 's 22 congressional district in the House from 2011 to 2013. Omar Aquino (born June 24, 1987) is a Democratic member of the Illinois Senate, representing the 2nd district.  He was elected in the March 2016 Democratic primary and appointed to the seat effective July 1, 2016, following the retirement of William Delgado.  At age 29, he is the youngest-ever Latino member of the Illinois State Senate and one of the youngest state senators in Illinois history.  Previously, he served as an aide to Congresswoman Tammy Duckworth. Terry de la Mesa Allen Jr. (1929–1967), son of retired U.S. Army Major General Terry de la Mesa Allen Sr., was a fourth-generation soldier.  He achieved the rank of lieutenant colonel in the U.S. Army.  He served with the 1st Infantry Division, which his father had commanded with distinction during World War II.  Allen was killed in an ambush in South Vietnam on Tuesday 17 October 1967 while leading his battalion against the Viet Cong near Lai Khe, northwest of Saigon at the Battle of Ong Thanh.
Answer: Tammy Duckworth