Czech police are hunting a thief who snatched the 800-year-old skull of a saint from a display box in a church and ran away with the relic.

A fuzzy security camera photo released late on Tuesday appeared to show a figure dressed in black carrying what police said was the skull of Saint Zdislava of Lemberk.

The suspect was seen running between the benches in the Saint Lawrence and Saint Zdislava basilica in Jablonne v Podjestedi, 110 km (68 miles) north of Prague.

“The value of the stolen skull is currently being investigated. However, its historic value is obviously incalculable,” said Dagmar Sochorova, a spokesperson for the police.

Saint Zdislava of Lemberk, a noblewoman, 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,” the archbishop of Prague, Stanislav Pribyl, who also heads the Litomerice diocese that is in charge of the Jablonne church, told the 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.”

Placed on an altar in a side chapel, the skull “was the subject of adoration for pilgrims travelling to Jablonne where Zdislava lived and worked more than 750 years ago”, Pribyl said.

Police initially identified the suspect as a man but a spokesperson later said that they were not sure and were evaluating material from the security camera.