Forensic Radiology: Response to the Pentagon Attack on September 11, 2001
The U.S. military has a time-honored commitment to its members and their families to recover those killed in service, identify their remains properly, and prepare them for appropriate honors and interment. The continued efforts to find those missing from the war in Vietnam and the recent identification of a serviceman from that conflict who was buried in the Tomb of the Unknowns at Arlington National Cemetery are evidence of this obligation (1). Following the September 11 attack on the Pentagon, as search and rescue efforts began, the process of recovery and identification of those who did not survive was also initiated. Forensic radiology was a key component in the system of casualty identification at the Port Mortuary, Dover Air Force Base, Del. Here, the Office of the Armed Forces Medical Examiner, augmented by a support group of more than 200 military and federal personnel representing all services and many agencies, undertook the identification of remains and forensic investigation of the deaths that occurred at the Pentagon. The military faced a situation unlike past experiences in war and peacetime accidents: a mass-casualty scenario, involvement of military and civilians, and the inclusion of terrorists among civilian casualties.
Radiographic analysis of the remains from this event was a crucial step in the identification of victims and the investigation of the crime scene. The Department of Radiologic Pathology at the Armed Forces Institute of Pathology, or AFIP, performed this step with support from the Diagnostic Imaging Department of the Dover Air Force Base Medical Clinic. Because of the extraordinary scope of the mass-casualty scenario created by the Pentagon attack, an additional radiologist and military technologists from two reserve components supported the mission. This staff operated up to 12 hours per day, 7 days per week, as required by the volume of recovered remains.
The mortuary has two radiographic rooms equipped with fixed overhead tubes. A daylight film-processing system arrived on the 2nd day of operation to replace a darkroom system. This system greatly reduced the time required to move specimens through the radiographic station. On review of the radiographs, the radiologist completed a report consisting of handwritten notations on a form that showed a schematic skeleton. The comments were brief and were designed to assist those performing other steps in the identification and investigation process, such as forensic dentistry, autopsy, and anthropologic assessment. The report and radiographs traveled with the specimen, and it was easy for professionals at other stations to compare their observations with the report and seek out the radiologist who completed the report for consultation and discussion.
Human remains that are recovered from a disaster site are highly variable in form and condition. Recovered bodies may have been subjected to extreme physical and thermal trauma. Casualties may result from crash impact, building collapse, or associated fire and smoke. The intense heat of burning fuel in aircraft accidents severely burns tissue, clothing, and furnishings. The process of recovery from beneath fallen rubble further alters tissues (2). Consequently, specimens ranging from relatively intact bodies to small body-part fragments were received from the Pentagon site. Whole-body radiography is one step in processing remains received at the military mortuary. Unfortunately, many specimens were received as body parts, often unrecognizable from their gross appearance and mixed with debris from the site. Each specimen designated for processing had an identification number assigned by the Federal Bureau of Investigation that linked it to its recovery location at the scene. Each specimen also received a mortuary control number.
In many cases, the whole-body radiograph established whether body parts, personal effects, or other materials were present in the specimen. The forensic radiologist reported all identifiable human structures and substantial objects recognized, along with comments on the condition of each. For example, we commented on the presence of fractures, the absence of anatomically contiguous body parts, and the presence of jewelry and/or personal effects. Also noted were distinguishing features that may aid in establishing the age of the victim (eg, the presence of skeletally immature bones or osteoarthritis in a knee) and identifying military personnel (eg, the presence of military insignia). The forensic dental team benefited from the discovery of teeth on a radiograph when they may not have been noted previously at gross inspection of the specimen. Since the event was known to be the result of a terrorist action, the radiologist also searched for any clues, such as weapons or aircraft parts, that might lead to a better understanding of the attack.
Interpretation of specimen radiographs poses a number of particular challenges for the forensic radiologist that are not typical for a clinical radiologist. Screening whole-body radiographs provide only one view of the specimen. Because of the very nature of the specimen, radiographs of body parts are often limited initially to a random projection that may not produce a familiar anatomic view of skeletal fragments. While this is particularly true of pieces of flat bones, such as the skull, pelvis, and scapula, a radiographic appearance of a long bone diaphyseal fragment may be problematic. The discontiguous arrangement of one or two vertebral bodies in a nonstandard projection can make identification of the level difficult. It may not always be feasible to obtain a second radiograph of the specimen because of workload and technical factors. In certain circumstances, employing a tested radiographic axiom (“go examine the patient”) by directly palpating the specimens in the bag may allow the forensic radiologist to learn more about their three-dimensional characteristics.
There is also the ever-present problem of debris. Virtually every specimen from this site was mixed with debris composed of aircraft and building materials of an opaque and semiopaque nature. Body parts from several individuals may have been mixed into a single specimen. In some specimens, this was apparent because skeletally immature bones and adult bones were contained in the same specimen bag. This is particularly true of appendicular skeletal structures, which are frequently detached during high-velocity impacts such as aircraft accidents (3).
The positive identification of remains is the responsibility of the medical examiner. Those working on individual steps in the process each contribute data used in making the decision. There are instances in which the data make identification relatively easy, and there are other circumstances that make identification impossible. Personal effects are not as substantial as one would imagine. Clothing can be borrowed, cards can be forged or stolen, and pieces can be scattered over distances and recovered with another body. The military anticipates the requirement of obtaining DNA specimens from all personnel and maintaining them in a central repository for postmortem identification purposes (4). In addition, dental records are maintained and usually include a full-mouth pantograph. The existence of a reference database allows relatively rapid positive identification of military casualties. This was, in fact, true with the Pentagon attack, since many more military casualties were positively identified than civilian casualties in the early stages of the investigation.
Radiologic services at the mortuary supported two tasks: remains processing and remains identification. Dental records and DNA reference samples may be sufficient in the final identification step for many military casualties. However, radiography of victims remains an essential asset of this process. This is especially true when reliable dental information is not available or when attempts to collect DNA from victims are hampered. Analysis of DNA is a powerful tool in military casualty identification, but it has limitations. The DNA sources from victims subjected to intense fire may denature and not be recoverable (5). The mass-casualty operation resulting from the Pentagon attack confirms the importance of forensic radiology as a key component of casualty identification.
The views expressed in this editorial are those of the authors and do not reflect the official policy of the Department of Defense or the Departments of the Army, Air Force, or Navy.
|1.||Arlington National Cemetery. Tomb of the Unknowns at Arlington National Cemetery. Available at: www.arlingtoncemetery .org/visitor_information/tomb_of_the_un knowns.html.. Accessed December 27, 2001.|
|2.||Mulligan ME, McCarthy MJ, Wippold FJ, Lichtenstein JE, Wagner GN. Radiologic evaluation of mass casualty victims: lessons from the Gander, Newfoundland, accident. Radiology 1988; 168:229-233.|
|3.||Lichtenstein JE, Madewell JE, McMeekin RR, Feigin DS, Wolcott JH. Role of radiology in aviation accident investigation. Aviation Space Environ Med 1980; 51:1004-1014.|
|4.||Armed Forces Institute of Pathology. Armed Forces Repository of Specimen Samples for the Identification of Remains: repository history. Available at: www.afip.org/Departments /oafme/dna/history.htm. 2001. Accessed November 15.|
|5.||Smith BC. Introduction to DNA analysis. Forens Odontol 2001; 45:229-235.|