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Carl Stephan

Forensic anthropologist uses chest radiographs to identify skeletons of soldiers

Carl Stephan

Pictured above, forensic anthropologist Dr. Carl Stephan is examining two hardcopy miniature chest radiographs that have been recorded on the same film. As part of the Joint POW/MIA Accounting Command Research Participation Program, he is developing chest x-ray analysis methods to help identify the U.S. soldiers fallen in the Korean War and buried at the National Memorial Cemetery of the Pacific.

Australian forensic anthropologist Dr. Carl Stephan will not be watching crime shows at the end of his day. A research participant at the Joint POW/MIA Accounting Command/Central Identification Laboratory (JPAC) at Hickam Air Force Base in Hawaii, Stephan said these television programs often do not reflect the reality of the methods, time or expertise needed in local-, national- and international-scale casework.

Stephan serves as a post-doctoral fellow in the JPAC Research Participation Program, managed by the Oak Ridge Institute for Science and Education. The program provides scientists with the opportunity to participate in research concerning recovery and identification of missing U.S. soldiers lost in the nation’s past conflicts.

For the past four and a half years, Stephan has conducted research that could help identify hundreds of fallen Korean War U.S. soldiers buried at the National Memorial Cemetery of the Pacific 56 years ago. As the lead research scientist for the highly collaborative project, Stephan dedicates his time to develop, test and validate methods of matching human remains to individuals on a long list of unaccounted-for individuals lost to the battle.

He already has published in excess of 15 scientific papers, presented more than 10 scientific research presentations at professional meetings and participated on two panels to develop best-practice guidelines for the Scientific Working Group for Forensic Anthropology.

“Essentially what we have done is develop the first tested and standardized infra-cranial (non-skull) method that uses skeletal anatomy to individuate individuals from samples of hundreds of potentially matching candidates,” said Stephan.

Stephan uses the anatomical details of the bones in the chest, instead of the DNA, to help the JPAC scientific director Dr. Thomas D. Holland assign a name to the remains. For the individuals buried at the National Memorial Cemetery of the Pacific, JPAC found that current DNA technology is simply not effective.

“The remains buried at the national cemetery were treated heavily with formaldehyde during the original examinations in the mid-1950s, a process that locks up the DNA, so it is extremely difficult to sequence,” explained Stephan.

Since 1942, the military has required every soldier to receive a chest x-ray to screen candidates for tuberculosis. Because the radiographic procedures are easy to mimic in the laboratory setting, these chest x-ray records are a gold mine for Stephan to assist Holland in identifying the fallen soldiers.

The clavicles and vertebrae on the x-rays are the focal points for Stephan because of their high variability between individuals, well-preserved state in field-recovered skeletons and clarity on most x-rays.

Using a 3D scanner, Stephan obtains a rotatable image of a clavicle from the skeleton of the individual who was buried in the cemetery then employs a biometric search algorithm to attempt to match that clavicle’s shape with the clavicles on ante-mortem x-rays of hundreds of individuals in the lab database.

The computer rotates the post-mortem clavicle scan until it finds a best-fit position with the ante-mortem chest radiographs of the candidates, and, after further analysis to quantify the shape, ranks all of the individuals in the database according to their similarity to the skeletal remains. In a matter of seconds, the computer generates a list of potential candidates.

“The radiographs for these candidates are compared by eye to the skeletal remains on high resolution computer screens,” explained Stephan. “Similar to the process of fingerprint identification, analysts look for dissimilarity in shape to eliminate individuals who do not match the remains; when discordances do not exist, overlays of the postmortem and ante-mortem clavicle radiographs are made to double check the precision of the comparison and that the correct individual has been found.”

In combination with an individual’s historical information, dental records and/or biological profile, the chest radiograph comparison method has tripled the number of identifications from the National Memorial Cemetery of the Pacific made during the last 56 years from eight identifications to 25.

As for his biometric algorithm method, Stephan is optimistic that it could be used to help identify about 400 more soldiers—those known to possess clavicles—at the National Memorial Cemetery of the Pacific.

Stephan said the driving force behind his current research is his desire to help provide closure where it is due, because in real life, unlike those prime-time moments, emotions are not scripted for the families of the missing.

“It is an absolute privilege to assist in identifying these soldiers, so they can be repatriated to their families,” said Stephan. “Each soldier was someone’s son, brother or father, and it is immensely important that these young men are returned home.”