The bodies of the first donors will be used to collect decomposition odours so forensic scientists can better understand how cadaver dogs find human remains, said Dr Shari Forbes, a forensic scientist with the University of Technology (Sydney) who heads the multiple-disciplinary facility. The skulls and bones of some of those who were slaughtered as they sought refuge inside the church are laid out as a memorial to the thousands who were killed in and around the Catholic church during the 1994 genocide in Ntarama, Rwanda. Credit:Ben Curtis But, in a new development, Victorian forensic archaeologists and anthropologists will also use the Sydney bush site to study the decomposition of co-mingled bodies in a mass grave, usually caused by political, religious or ethnic violence. Human decomposition was affected by many variables, said Dr Soren Blau, a forensic anthropologist who will direct the mass grave project. She has worked on mass graves in Timor Leste and the Solomons. When bodies are co-mingled, it becomes even more complicated. "We know that with one individual it (human decomposition) is complex, but when you add many individuals, the complexity becomes even greater," said Dr Blau, the senior forensic anthropologist with the Victorian Institute of Forensic Medicine.

The research could assist investigators looking for mass graves, researchers examining remains and prosecutors of war criminals. For instance, a defence team argued that the remains of 300 people found in a mass grave in the Balkans had been killed in two separate incidences. This could have weakened the prosecution's case for a conviction for genocide. But experts found that the 300 people had been killed and placed there at the same time, yet the rate of decomposition varied enormously within the one grave. The project's co-director is Jon Sterenberg, a forensic archaeologist who was head of the the International Commission on Missing Persons (ICMP) excavation and examination division in Croatia, Serbia, Kosovo, Montenegro and Bosnia and Herzegovina. The Sydney research would complement a similar research project being undertaken in Tennessee at a facility made famous in Patricia Cornwall's novel, The Body Farm. In the Australian research project, six individuals would be interred in one grave, and three individuals in another. The graves would be dug using two different techniques, hand dug and machine dug (often used by perpetrators of war crimes). They would also dig empty graves as a control. Also, many war criminals dig empty graves to create fear. Over three years, researchers would monitor changes in soil composition, insect behaviour and other aspects. They'd also test the effectiveness of remote-sensing techniques used to locate human remains. At the end of three years, the remains would be exhumed and studied.

Professor Forbes said it was unusual for the site to receive three donors at once, but she was happy to start after years of planning. "We were stoked to start," she said. But Sydney's changing weather had slowed things down. "It (decomposition) hasn't happened as quickly as we thought, although it is going fairly quickly. It is summer, it is hot out there, but the rain has slowed things," said Professor Forbes. Each of the bodies has been placed on the soil or in a shallow grave, protected from animals by some mesh, where nature is allowed to take its course. She visits the site every day to figure out "what decomposition smells like, and how dogs can track that. I will trap the odours and take that to the dogs for training."