LUKAVAC , Bosnia-Herzegovina ( CNN ) -- The man 's remains lie on a table . Next to him are the bones of his 22-year-old son and the remains of another son . But no one yet knows which of the man 's two missing boys the third set of remains could be . Cheryl Katzmarzyk measures a leg bone as she puts together remains from Srebrenica . Cheryl Katzmarzyk wants to be able to put a name to the remains , and to those of hundreds of other bodies stacked around her in a building in Lukavac , near Tuzla in the northeast of Bosnia . The bones are from more than 8,000 men and boys slaughtered in 1995 during the Bosnian war at Srebrenica in the worst massacre in Europe since World War II . The killers -- Serbs seeking to drive out Bosnian Muslims in a policy of `` ethnic cleansing '' -- executed the region 's fighting-age males , then used bulldozers to dump them into mass graves . What makes the work harder for the teams trying to put the bodies back together -- so they can be returned to their families for proper burial -- is that so many have been broken up over the years . Mass graves were dug up and the bodies moved sometimes again and again , to hide evidence as the Serbs retreated amid the NATO bombing that followed Srebrenica and led to the end of the war . Those killed in a warehouse execution at Srebrenica are spread throughout 20 secondary grave sites , for instance . Katzmarzyk said remains of one of the victims was found in eight different parts of one mass grave . Another man 's shoulder was found where he and others were lined up and shot , one of his legs was found near a grave , a hip was found inside the grave , his upper jaw several miles away and his left arm in a secondary grave . `` What we do here is we sort them out , '' said Katzmarzyk , the head of anthropological examinations for the International Commission on Missing Persons . Katzmarzyk 's team from the ICMP -- a nongovernmental organization set up at the end of the Bosnian war to locate and identify victims of war and human rights abuses -- has pioneered quicker , simpler DNA tests to work out which bones go together . Watch an audio slideshow about the ICMP 's work » . Then , a more extensive DNA test is done to see if there is a match with any of thousands of relatives who have donated their own samples in the hope of finding missing relatives . But DNA can only go so far , and while it can show that the unidentified remains on Katzmarzyk 's table are those of a man and his 22-year-old son , it can not say whether the third set belongs to a missing 21-year-old or his 24-year-old brother -- because neither had children to act as an extra reference point . It 's a particular problem with identifying the Srebrenica dead because so many of the victims were related . Across the room , brothers lie next to each other , but as yet the scientists do not know who is who . So Katzmarzyk and her colleagues are also experts in forensic anthropology , using other pointers to make an identification . They will look for clues to the age of the remains and any other factors that could identify them : Did the man break his leg as a child ? What clothes was he wearing ? How tall was he ? `` We started to look at clothing , place of disappearance , '' said Katzmarzyk . `` We use all kinds of evidence to identify as many people as possible . '' Watch a Bosnia concentration camp survivor describe the torture and rape she witnessed » . About 5,200 people out of the 8,000 executed at Srebrenica have been identified with the help of ICMP , but new mass graves continue to be found and more remains are delivered to the facility in Lukavac to be matched . Years of work lie ahead -- if governments continue to contribute to the project . `` We still have many more IDs to make , but what we need are additional funds to ensure that the process is completed . It 's essential . ... This is a unique contribution to the investigation of genocide , '' said Katzmarzyk , who was recently working on 842 sets of remains , all but one of them male . Evidence gathered by the ICMP about the Srebrenica genocide could also be used against former Bosnian Serb leader Radovan Karadzic , who is set to face trial at The Hague , accused of ordering the massacre . ICMP helped identify victims of Hurricane Katrina and the Asian tsunami , but its main work continues in the former Yugoslavia , where the condition of the remains makes it vital to use DNA , forensic anthropology and anything else to piece skeletons together and give them a name . `` The ICMP is unique in that all these lines of inquiry are used together , '' Katzmarzyk said . `` DNA is essential , anthropology is essential . '' The work is challenging scientifically and sometimes emotionally , she said . It is rewarding and satisfying to identify remains and allow them to be released to the coroner and then to the family . But some cases are more haunting . `` The fact that I have three brothers lying side by side on a table -- how can that not affect you ? '' Katzmarzyk asked . `` And there 's a fourth brother missing . ''
Scientists piece together remains of massacre victims . Many of the victims slaughtered at are still not identified . It uses mix of DNA and forensic anthropology .