A fuzzy security camera photo showed a silhouette dressed in black with what police said was the skull of Zdislava of Lemberk in their hands running between the benches in the Saint Lawrence and Saint Zdislava basilica in Jablonne v Podjestedi, 110 km (68 miles) north of Prague, on Tuesday.
Saint Zdislava of Lemberk lived from 1220 to 1252 and was known for her generosity and work for the poor. She was canonised by Pope John Paul II in 1995.
"This is devastating news," Prague Archbishop Stanislav Pribyl told news agency CTK.
"The skull was revered by pilgrims... I cannot believe that someone practically in broad daylight steals from church a relic whose value is above all historical and also spiritual for believers."
Police identified the suspect as a man but a spokeswoman later said that they were not sure and were evaluating material from the security camera.
(Reporting by Jan Lopatka; editing by Barbara Lewis)

Faithful participates in the Easter vigil mass in St. Vitus Cathedral at Prague Castle, as Christians commemorate the crucifixion of Jesus Christ, in Prague, Czech Republic, 04 April 2026. The Holy Saturday observance commemorates the final day of Christ's death. EPA/MARTIN DIVISEK