Question: What city did the key suspect in the 2001 anthrax attacks work in?

full_context: Document 1: Robert Stevens (photo editor): Robert K. "Bob" Stevens (June 20, 1938 – October 5, 2001), an American photojournalist for the "Sun", a subsidiary of American Media, located in Boca Raton, Florida, United States was the first journalist killed in the 2001 anthrax attacks when letters containing anthrax were mailed to multiple media outlets in the United States. The anthrax attacks also killed four others in the United States and sickened seventeen others.
Document 2: BioWatch: BioWatch is a United States federal government program to detect the release of pathogens into the air as part of a terrorist attack on major American cities. Reportedly operating in Philadelphia, New York City, Washington, DC, San Diego, Boston, Chicago, San Francisco, Atlanta, St. Louis, Houston, Los Angeles and 21 other cities, the BioWatch program was created in 2001 in response to the increased threat of bioterrorism sparked by the 2001 anthrax attacks, and was announced in President George W. Bush's State of the Union Address of 2003.
Document 3: United States biological defense program: The United States biological defense program — in recent years also called the National Biodefense Strategy — began as a small defensive effort that paralleled the country's offensive biological weapons development and production program, active between 1943 and 1969. Organizationally, the medical defense research effort was pursued first (1956-1969) by the U.S. Army Medical Unit (USAMU) and later, after the discontinuation of the offensive program, by the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID). Both of these units were located at Fort Detrick, Maryland, where the U.S. Army Biological Warfare Laboratories were headquartered. The current mission is multi-agency, not exclusively military, and is purely to develop defensive measures against bio-agents, as opposed to the former bio-weapons development program.
Document 4: Arturo Casadevall: Arturo Casadevall is a Bloomberg Distinguished Professor of Molecular Microbiology & Immunology and Infectious Diseases at the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins School of Medicine, and the Alfred and Jill Sommer Professor and Chair of the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. He is an internationally recognized expert in infectious disease research, with a focus on fungal and bacterial pathogenesis and basic immunology of antibody structure-function.
Document 5: 2001 anthrax attacks: The 2001 anthrax attacks, also known as Amerithrax from its Federal Bureau of Investigation (FBI) case name, occurred within the United States over the course of several weeks beginning on September 18, 2001, one week after the September 11 attacks. Letters containing anthrax spores were mailed to several news media offices and two Democratic U.S. Senators, killing five people and infecting 17 others. According to the FBI, the ensuing investigation became "one of the largest and most complex in the history of law enforcement."
Document 6: Building 257: Building 257, also known as Lab 257, was a United States biological warfare research laboratory located at Fort Terry on Plum Island, New York. Originally intended for munitions storage, the facility researched anti-animal biological agents beginning in 1952 under the United States Army. Biological warfare research continued in the building under the United States Department of Agriculture (USDA) until a new laboratory was completed.
Document 7: Dwight D. Eisenhower Army Medical Center: The Dwight D. Eisenhower Army Medical Center (EAMC) is a 93-bed medical treatment facility located on Fort Gordon, Ga., located near Augusta, Georgia that previously served as the headquarters of the Army's Southeast Regional Medical Command (SERMC). SERMC oversaw the Army's hospitals and clinics within the southeastern United States and Puerto Rico. SERMC was renamed Southern Regional Medical Command (SRMC) and was relocated to San Antonio in 2009.
Document 8: Building 40 (Army Medical School): Building 40, Army Medical School is a Georgian revival structure in the Walter Reed Army Medical Center complex in northern Washington, D.C., USA. It was built between 1922 and 1932 to house the Army Medical School, which became the Army Medical Center in 1923 when it — under the name “Medical Department Professional Service School” (MDPSS) — combined with the Walter Reed General Hospital. The MDPSS ultimately became the Walter Reed Army Institute of Research, which occupied Building 40 from 1953 to 1999. It comprises four wings, known as the Craig (1924), Sternberg and Vedder (1932), and Siler (1962) Pavilions and is situated at 14th and Dahlia Streets.
Document 9: Maurice Hilleman: Maurice Ralph Hilleman (August 30, 1919 – April 11, 2005) was an American microbiologist who specialized in vaccinology and developed over 40 vaccines, an unparalleled record of productivity. Of the 14 vaccines routinely recommended in current vaccine schedules, he developed eight: those for measles, mumps, hepatitis A, hepatitis B, chickenpox, meningitis, pneumonia and "Haemophilus influenzae" bacteria. He also played a role in the discovery of the cold-producing adenoviruses, the hepatitis viruses, and the cancer-causing virus SV40.
Document 10: Fort Detrick: Fort Detrick is a United States Army Medical Command installation located in Frederick, Maryland. Historically, Fort Detrick was the center of the US biological weapons program from 1943 to 1969. Since the discontinuation of that program, it has hosted most elements of the United States biological defense program.
Document 11: One-Million-Liter Test Sphere: The One-Million-Liter Test Sphere — also known as the Test Sphere, the Horton Test Sphere, the Cloud Study Chamber, Building 527, and the “Eight Ball” (or “8-ball”) — is a decommissioned biological warfare (BW) chamber and testing facility located on Fort Detrick, Maryland, USA. It was constructed and utilized by the U.S. Army Biological Warfare Laboratories as part of its BW research program from 1951 to 1969. It is the largest aerobiology chamber ever constructed and was placed on the National Register of Historic Places in 1977.
Document 12: Anthrax hoaxes: Anthrax hoaxes involving the use of white powder or labels to falsely suggest the use of anthrax are frequently reported in the United States and globally. Hoaxes have increased following the 2001 anthrax attacks, after which no genuine anthrax attacks have occurred. The FBI and U.S. postal inspectors have responded to thousands of "white powder events" and targets have included government offices, US embassies, banks and news organizations.
Document 13: Walter Reed Army Medical Center: The Walter Reed Army Medical Center (WRAMC) — known as Walter Reed General Hospital (WRGH) until 1951 — was the U.S. Army's flagship medical center from 1909 to 2011. Located on 113 acre in Washington, D.C., it served more than 150,000 active and retired personnel from all branches of the military. The center was named after Major Walter Reed (1851–1902), an army physician who led the team that confirmed that yellow fever is transmitted by mosquitoes rather than direct contact.
Document 14: Forest Glen Annex: The Forest Glen Annex is a 136 acre U.S. Army installation in the Forest Glen neighborhood of Silver Spring, Maryland, USA. It is situated between Brookville Road and Linden Lane. Since 1999, the Annex has been the site of the Walter Reed Army Institute of Research (WRAIR) and the Naval Medical Research Center (NMRC), along with smaller units. In addition to the large research laboratories located in the Annex’s "Daniel K. Inouye Building" (Building 503), the post includes a commissary, a child care center, and a Fisher House. There are also football and baseball fields, and picnicing facilities. In 2011, in accordance with the most recent Base Realignment and Closure (BRAC) recommendations, the Forest Glen Annex became home to the National Museum of Health and Medicine (NMHM) as well as a "Joint Center of Excellence in Infectious Disease Research." The former post exchange was repurposed as office space and a new Army and Air Force Exchange Service (AAFES) was opened at the Walter Reed National Military Medical Center.
Document 15: Bruce Edwards Ivins: Bruce Edwards Ivins (April 22, 1946 – July 29, 2008) was an American microbiologist, vaccinologist, senior biodefense researcher at the United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, Maryland, and the key suspect in the 2001 anthrax attacks.
ground_truth: Frederick, Maryland