This story appears in the July 2017 issue of National Geographic magazine.

When British archaeologist Max Mallowan investigated the neo-Assyrian site of Nimrud in northern Iraq, he got help from someone who loved detective work—his wife, Agatha Christie. Despite her busy career, the mystery writer made time every winter from 1949 to 1957 to register and photograph the artifacts that her husband’s excavations brought to light.

View Images Agatha Christie photographs one of the several thousand finely carved ivories found at Nimrud. Many of the pieces originally adorned furniture and arrived in the capital as booty or tribute from cities near the Mediterranean coast. Photograph by BETTMANN ARCHIVE/GETTY IMAGES

She probably also took the picture of the stone relief shown in black and white. That art, which once adorned a palace wall, depicts a priest performing a ceremony before a motif called a tree of life. But the photo reveals something curious—a cut around the priest’s head. Looters in the 19th century are possible culprits, but so are invading soldiers in antiquity.

The city of Nimrud, known as Calah in the Bible, became the capital of the neo-Assyrian Empire in 883 B.C., under King Ashurnasirpal II. At the end of the seventh century B.C., the empire collapsed and a coalition of enemies sacked the city. The relief of the priest may have been damaged deliberately in that attack. “We know many things were desecrated as part of the sacking,” says Mark Altaweel, a Mesopotamia expert at University College London.