In a transparent envelope, in a cardboard box in the archives of the Open Society in Budapest, there is a plastic comb. It is cheap and brown. The comb once belonged to a man killed at Srebrenica. We will never know whose it was. The victims were buried together at first, and then some were moved and reburied, so the parts of many corpses are still all jumbled up. The comb is part of David Rohde’s archives – Rohde was the brave American reporter who travelled into Serbian-controlled Bosnia and first uncovered the mass graves. It is, in its way, quite as chilling as the piles of glasses and shoes at Auschwitz.