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The Science of War

How DNA puts a face on the missing.

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To a distraught parent whose child has gone missing, the unique genetic code embedded within every cell of the human body is of particular value. That code, spelled out in A’s, C’s, T’s, and G’s, may reveal that their loved one is among the anonymous dead. Hundreds of thousands of people disappear every year around the world because of natural disasters, wars, crimes, and treacherous journeys to other countries. They often leave behind family members, who now may turn to an international organization that specializes in decoding the identities of the deceased.

The Bosnia-based International Commission on Missing Persons (ICMP) formed in 1996 at the behest of former United States President Bill Clinton, with the aim of identifying thousands of people who went missing during conflicts in Bosnia, Croatia, and the former Republic of Yugoslavia. Many of the bodies recovered from that period had been mangled beyond recognition, so the ICMP established a system for extracting DNA from bones and matching it to DNA donated from people from the region. The group identified nearly 17,000 missing individuals. They have gone on to analyze DNA from victims of the South Asian tsunami of 2004, Hurricane Katrina in 2005, Typhoon Frank in the Philippines in 2008, and people who “disappeared” during Pinochet’s reign in Chile. Nautilus caught up with the director of forensic science at the ICMP, Thomas Parsons, to learn what goes into these investigations.


How do you identify a person by their DNA?

One way would be to compare the DNA from a recovered body to DNA found on a missing person’s razor, toothbrush, or items like that. Computationally, this gives the most reliable result because you are looking for an exact match. However, misidentifications can happen if someone else used the object. For that reason, we compare DNA samples to those donated from a missing person’s mother, father, sisters, and brothers. We now have a database of almost 90,000 reference profiles against which every DNA profile we get is screened. We do the calculations to determine the statistical surety of the relationship, and we only report it when we are at least 99.95 percent confident that we have a match. If a mother has several missing offspring, the analysis is tricky. We can tell if individuals shared a mother, but DNA alone cannot discern one sibling from another.

Have you learned about relationships that might come as a surprise to the missing person’s family?

We have access to information about how families are related to each other, but we realize how sensitive that can be. We have well-established rules of confidentiality, and firewalls on our databases because it is critical that these incidental findings are not released. In some parts of the world, a woman might be killed for infidelity. If we find that a missing person is related to their mother but not to their supposed father, it would be absolutely unethical to say this is not the father. We would never do that.

Are people reluctant to hand over their DNA?

Occasionally, but most of the time it’s the families who come forward and say they want to do this. They’re often the ones who network among themselves and go to the government and say that they’d like us to look into missing persons. You can’t underestimate the importance of grassroots public outreach. For example, because a large number of refugees from the former Yugoslavia live in St. Louis, Mo., we sent a collection team there. We advertised our services in newspapers, and then word about us circulated among the broader community.

Are some remains too deteriorated for DNA analysis?

Yes. We are dealing with highly degraded DNA, and in many cases, the only thing left are skeletal remains. In general, DNA from heavily burned bodies or from people buried in hot and wet environments with lots of microbial activity is in worse shape than DNA collected from cold and dry places. However, it’s almost always worth seeing what you can get. Every year we improve our techniques by staying up to date on the latest methods for sequencing ancient, degraded DNA. The methods that scientists use to retrieve DNA from humans that lived thousands of years ago are similar to the techniques we use for assessing DNA from deteriorated bodies that were mangled or not properly buried. Recently, we successfully obtained DNA profiles from severely burned victims of the train crash explosion in Lac-Megantic, Quebec.

We’re also excessively cautious about contamination because the techniques we use detect minute quantities of DNA. If the researcher sequencing the sample sticks their thumb in a test tube, they’ll sequence their own DNA instead of that from the sample. So we use gloves, masks, dust-proof hoods, and in addition we include the DNA from anyone who works at our facilities in our database. That way, if a sample matches one of them, we’ll know it was contamination. That happens very rarely—a couple of instances in tens of thousands of tests—but when it does we write up a report to figure out what occurred so that we prevent it from happening again.

Are there people who would rather your DNA investigations didn’t exist?

Yes. Political issues are huge. We have been involved in some divisive nationalistic conflicts that involve the prosecution of war criminals, and clearly there are people who would prefer to tell their version of history. Specifically, some of the data we’ve uncovered shows there was systematic mass killing of approximately 8,000 men and boys in the Srebrenica massacre of 1995. It may be used in the United Nations’ criminal tribunal against Radovan Karadžić, ex-president of the Serb Republic, and Ratko Mladić, who was a former military leader. People who are loyal to them argue that there were perhaps just a few hundred or a few thousand deaths, mainly combatants. That’s why online, you’ll see parties that falsely discredit our work.

Another problem is that some people only want to expose the deaths of select groups. For example, as Libya confronts the issue of identifying the missing people in their country, some parties show greater interest in knowing the identity of disappeared people who resisted the Gaddafi regime, rather than loyalists to Gaddafi that also went missing. Families, meanwhile, grieve and want answers no matter side of the conflict their loved ones were on.

Traditional means of identifying the dead: Prior to the use of DNA technology, personal items such as watches, jewelry, and false teeth were used to help families recognize their relatives’ remains. At the ICMP’s mortuary in the city of Tuzla in northeastern Bosnia, personal belongings exhumed from mass graves are collected and logged. Here, an identity card and a pair of spectacles are retrieved from a burial site.
Bones preserve DNA best: The right femur of a victim sits next to a skeletal inventory card. To obtain a DNA sample, a sample of the bone would be cut, then ground down, and dissolved in a chemical solution to extract the genetic material. An individual profile can be obtained by examining the pattern of nucleobases along the DNA strands. Then the living relatives are asked to provide blood samples to create their own DNA profile. The two profiles are compared using ICMP’s database of more than 90,482 living relatives of the missing and 543,328 bone samples taken from human remains. A victim is fully identified when the statistical likelihood of a match is 99.95 percent or greater.
In the aftermath of the Balkan Wars: The ICMP was created in order to give families psychological closure by identifying the dead and returning the bodies, wherever possible. In the case of Srebrenica, it was very hard to identify the dead, because in the aftermath of the massacre the Bosnian Serb forces dug up the dead, weeks after their executions, with bulldozers and then reburied them in multiple different graves.
Putting a body back together: During burial and reburial, the body of one male victim from Srebrenica was broken up by mechanical equipment and found spread between four different mass graves. An ICMP staff member examines the vertebra of a human spine, in order to be sure that the bones she puts back together belong to the same body.
Finding the bodies: Mass graves are crime scenes. In Iraq, Bosnia, Libya, and Chile bodies have been buried in forest clearings, under bulldozed buildings, and down mineshafts. Parking lots have even been built in part to hide mass gravesites. Eighteen years after the Bosnian war ended in 1995, the ICMP are exhuming a municipal garbage dump in Sarajevo in search of missing.
Finally putting them to rest: Funerals of newly identified bodies of Srebrenica massacre victims take place every year on July 11. The remains are placed in coffins draped in green cloth. In this image, a relative of one of the victims searches rows of coffins laid out prior to burial.
Gathering evidence for the International Court: A mass grave was found in this small hamlet in eastern Bosnia. The corpses, pictured here, were identified as those killed in Srebrenica five miles away. In addition to DNA evidence, experts gather physical evidence: patterns of truck tires in the mud, as well as plants, bullet casings, and soil residue that travelled with the bodies as they were moved. This provides evidence in the ongoing trials of Bosnian Serb leaders Radovan Karadzic and Ratko Mladic, at The Hague.
Cross matching DNA : To make matches between victims and families, DNA is extracted from bones of the victims. Here, an ICMP technician holds a human bone sample.
Starting with the evidence: Human skulls recovered from mass graves often bear signs of execution, with bullet entry and exit holes. But when it comes to extracting DNA for identifications, scientists go looking for it in the teeth or in femurs. These are the hardest bones in the body, so they best resist oxidization.
Using a tooth to assess time of death : Here an ICMP bone expert examines the jawbone of a Bosnian victim of Srebrenica. By examining the translucency of the root of one of the incisor teeth she assesses age at time of death. Such technical procedures help forensic anthropologists build up a composite picture of each individual body.
A very detail oriented job: At a huge mortuary built in 1999 in northern Bosnia, body parts lie on an autopsy table. There are 206 bones in the adult body. With an estimated 8,100 persons killed at Srebrenica, well over a million bones and body parts had to be found.
Assembling a dead body to return to relatives: The ICMP has become a rare Bosnian success story in the wake of the wars in the Balkans. With the consent of victims’ relatives, information from its DNA identifications is now used as evidence at The Hague in war crimes trials. The ICMP is making it possible to hold those guilty of atrocities accountable for their crimes. Scientific evidence can now be used in court, to help prove beyond a reasonable doubt what atrocities were committed, and who should be held responsible.


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