By sampling pollen from victims in a mass grave, scientists may have sniffed out what time of year the men were executed--crucial evidence that could shed light on the identity of their murderers. The novel approach, outlined in the current Nature, may be a promising technique for future investigations.
In 1994, construction workers in Magdeburg, Germany, unearthed a gruesome find: skeletons of 32 men who had been murdered and buried together. Officials called in Reinhard Szibor, a forensic scientist at the Otto von Guericke University in Magdeburg. Because there had only been two mass killings in recent local history, Reinhard and others guessed the victims were either Germans executed by the Gestapo in April or May of 1945, or Soviet soldiers killed by the Soviet secret police during an uprising in the former East Germany in late June 1953. Szibor thought he might be able to distinguish between a spring and summer execution by analyzing pollen in the skeletons.
To test this idea, Szibor's graduate student, Christoph Schubert, tracked pollen counts in his own nose for a year using what he termed a "handkerchief test"--after blowing his nose, he would identify the types of pollen in the mucus using light and scanning electron microscopes. His pollen matched the official records for that year, with alder, hazelnut, willow, and juniper prominent in the spring, then plantain, sagebrush, lime tree, and rye in late June.
When Szibor's group rinsed pollen--which can last for hundreds of thousands of years--from the bones forming the nasal passages of two skulls, they found mainly plantain, lime tree, and rye pollens, suggesting a summer execution. (The group found no pollen elsewhere on the skeleton, suggesting the stuff they did find was left after the nasal tissues decayed.) Other evidence suggests the corpses are Soviet soldiers. Szibor points out that the Gestapo rarely dug mass graves in the middle of a city. And the skeletons showed decayed teeth but little dental work--typical of Soviet soldiers of that era.
The technique is "food for thought," says Jerry Melbye, a forensic scientist at the University of Toronto, who thinks it might be useful for future forensic work. Researchers have used ancient pollen to date archeological sites, he says, but this is the first time its been used to try to finger murderers.