How do you find the killer in a 6000-year-old murder mystery? It helps if you check for diatoms. New evidence—including fossilized phytoplankton—in sediments on Papua New Guinea’s northern coast suggests that the owner of a 6000-year-old human skull unearthed there some 85 years ago was killed by a tsunami, The New York Times reports. Other evidence in the sediment layers includes geochemical signatures characteristic of seawater, researchers report this week in PLOS ONE. That may make it the world’s oldest human tsunami victim, say the researchers, and it may warrant a reexamination of other costal sites with human fossils.