Bridges of bone and blood

Ten years and more after conflict fragmented the former Yugoslavia, many thousands of people from the region are still missing. Gradually they are being accounted for, as scientists with the International Commission on Missing Persons (ICMP) use various methods to identify their mortal remains. More than 7000 people have now been identified, of these more than 2000 were victims of the Srebrenica massacres, which present a particular challenge to the experts.

Birds are singing loudly in the trees next to a burbling stream. The sun is shining and the houses strung out along the single-track road look charmingly picturesque. But just a few paces to the side of the lane the grass and soil have been scraped away to reveal a less attractive scene – a random jumble of densely packed human bones.

This is the fourth mass grave to have been found in this village alone. It lies well within view of a nearby house. Protected from the sun by a large awning, donated by an aid agency, people are picking away the soil with trowels and precisely noting the number and positions of all the bones revealed. These are forensic anthropologists and forensic archaeologists.

Experts in bone
“Anthropologists in this context are experts in altered states of bone, in saying ‘this is human, this is male, this is elderly’, and we can be reasonably precise in those estimates,” explains Dr Mark Skinner, an anthropologist with Simon Fraser University in Burnaby, Canada, who is currently Director of the Forensic Sciences Department at the ICMP.

“Forensic archaeology is a very young discipline,” he adds. It has been used by the ICMP since 2002, “for the purpose of trying to understand how sites were created and the contents of those sites.” The very careful excavations carried out by these expert teams maximise the chances of recovering whole – or almost whole – skeletons from such graves.

“We know there’s one individual whose remains have been found in five different sites”, Dr Skinner says. “We know there’s another individual whose remains were found thirty kilometres apart – this is after we’ve excavated, submitted bone samples for DNA and have realised this individual’s parts have been distributed across many sites.”

DNA fingerprinting
The ICMP began using genetic fingerprinting techniques in 1999, as a last step in the process of identification. But, according to Deputy Director of Forensic Sciences Adnan Rizvic, “now we’re using DNA fingerprinting like a first step” – a “forensic revolution” which has dramatically increased the rate and number of identifications.

There are two main thrusts to the genetic work. Firstly, DNA extracted from disinterred bones is compared to all other known bone samples to try and re-assemble bodies; because this is a question of matching identical DNA from one person, it’s sufficient to focus on just seven key areas or ‘loci’ on the genetic material, ICMP has shown. Secondly, bone samples are also checked against DNA profiles derived from the blood of living relatives, who donate a mere four drops for this purpose.

Matching exercise
Because their DNA is not identical but does have some overlapping characteristics – a child gets half its genes from its father and half from its mother, while a sibling has a different combination of the parents’ genes – 16 loci are included in the matching exercise.

“That’s the reason we collect more than one blood sample per missing person,” says Adnan Rizvic. The more samples there are to compare against, the greater the statistical probability that an apparent match is genuine. In fact ICMP’s own standard is that the match must be at least 99.95 percent certain before the name of the individual can be passed on to a pathologist, who then checks all the evidence before making a final official identification.

Before the ICMP proved the success of this approach, it was generally believed that the application of DNA technology to identify remains on such a mass scale would be impossible.

It works thanks to a number of specialised databases that were devised by the ICMP, as well as software which can find potential matches for the DNA samples within just a few seconds. The organisation has also refined the standard processing and analysis techniques and developed a new type of chemical which makes the work much cheaper.

Piecing together the skeletons
To help keep costs down, it’s the task of the forensic anthropologists to minimise the number of bone samples sent for analysis. In special facilities where the remains are cleaned and examined, they ‘re-associate’ as much of an individual skeleton as possible, before cutting out a small piece to be sent to the lab.

Cheryl Katzmarzyk, who heads the Lukavac Reassociation Centre says, “I spend a lot of my time locating and recovering the samples to ensure family members receive as much as possible of their loved one” once the identification process is complete.

“Still it takes money,” says Adnan Rizvic. “We developed our labs to work at a very high capacity, but we need more bones and more money for chemicals in order to speed up the process.” The bottleneck comes early in the identification process. Until now almost all graves have been found after tip-offs from informants. Although information is received by government representatives almost every day, it’s believed there are still very many more grave sites to be discovered in the region. Even after they are located and the bodies exhumed, the ICMP can only begin its scientific work once the officials hand over the bones.

Satellite techniques
ICMP has recently been collaborating with researchers from Britain and the USA to see whether it’s possible to pinpoint previously unsuspected mass grave sites, using a combination of ‘remote sensing’ techniques. For example, detailed satellite imagery could spot changes in vegetation cover or different minerals brought to the surface by digging, while resistivity equipment could reveal areas of disturbance by measuring contrasts in the way that an electrical impulse passes through the soil. “If we can show correspondence between far and close imagery,” hopes Mark Skinner, “we may be able to go anywhere in the world and apply this technology.”

The occurrence of secondary mass graves in such numbers may be unique to the Srebrenica massacres – unfortunately the phenomenon of many thousands of missing persons is not. ICMP not only helped in identifying victims of the terrorist attacks on the World Trade Centre in New York in 2001 and is now helping post-Tsunami, it is also training Iraqi nationals to tackle their even larger problem with this issue.

However, the organisation remains very much committed to its ongoing work in Bosnia and throughout the region formerly known as Yugoslavia. 85 percent of its scientific staff are local nationals and Adnan Rizvic feels he speaks for them all when he says, “I must be proud, although it’s sad, that Bosnia is now the world’s leading country when it comes to DNA testing skeletal remains.” But he concludes, “the local staff is more than proud that we are working to assist our own country, to become stabilised and go forward into the future. Without solving the issue about the missing that will not be possible.”

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Bridges of bone and blood
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