ISIS has reportedly beheaded an 82-year-old antiquities scholar in Syria’s ancient city of Palmyra, the country’s antiquities chief said Tuesday. Militants hung Khaled Asaad’s body on a column in the city’s historic main square, said Syrian state antiquities chief Maamoun Abdulkarim. Asaad served as the head of antiquities in Palmyra for more than 50 years and worked with U.S., French, German and Swiss archaelogists on research on Palmyra’s 2,000-year-old ruins. He was detained and interrogated for more than a month by the militants, Abdulkarim said. ISIS militants seized control of Palmyra from government forces in May, raising fears of the destruction of the Roman-era structures.