Picture a graveyard in the desert at Abydos, Egypt, roughly 3000 B.C. Dozens of simple chambers line up in neat rows, surrounding the tomb of a king. Inside each chamber lies a single person, sometimes with a coffin, sometimes with a few ceramic pots or an ivory figurine.

When the British archaeologist Flinders Petrie first dug here in the 1920s, he counted too many deaths occurring too close together to be a coincidence. Yet he could find no wounds on the bones. The mystery was filed away, half-solved, for a century. Now it has been reopened.

Dr. Roselyn Campbell of Purdue University led a reexamination of a sample of these skulls using forensic techniques unavailable to Petrie, methods originally developed to investigate modern crime scenes. What she found was striking: at least 39% of the individuals studied show cranial trauma severe enough to have been fatal. That is a remarkably high proportion for people supposedly buried around the same time as their king, and it strongly supports the theory of retainer sacrifice, in which attendants are killed to serve a ruler in the afterlife.

What makes the discovery unsettling is not just the violence, but the silence surrounding it.