Celts killed each other. During the Iron Age, they’d stab, bludgeon, hang, and strangle their victims, then dump them in the sphagnum bogs that dot Northern Europe, sometimes with the ropes still around their necks.

We know this because the acidity of the bog water, the cold temperature, and the lack of oxygen have effectively prevented these corpses from decomposing. More than 700 bodies have been recovered, some as old as 10,000 years and some still appearing fresh enough to be mistaken for recent murder victims.

The “Grauballe Man,” above, was found in 1952 by a Dane digging for peat. His throat was cut in 290 B.C., but his body was well enough preserved to yield fingerprints. Why was he killed? Maybe ritual, maybe execution for a crime, maybe human sacrifice. Here’s one odd clue: Judging from their nutrition and manicures, the bodies appear consistently to have been from the upper classes.