Czech police have found the skull of a 13th-century saint, days after it was stolen from a church in the north of the country.

Police said they had arrested a suspect, who they said admitted to taking the skull of Saint Zdislava of Lemberk from a glass shrine in the basilica of St Lawrence and St Zdislava in the town of Jablonné v Podještědí on Tuesday.

The 35-year-old man had objected to it being displayed, police said, and had intended to cover it in concrete and dispose of it in a river.

“We know he wanted to sink it in the river today to bid farewell in this way,” the local police chief Petr Rajt told reporters. “If we had failed to detain the man yesterday, the skull would probably never be found.”

The man had already covered the skull in concrete, police said, leaving experts facing an uphill task to restore it.

St Zdislava of Lemberk, who was born around 1220 and died about 30 years later, was a noblewoman known for her charitable deeds and was canonised by Pope John Paul II in 1995.

The man was detained in the city of Mladá Boleslav north-east of Prague on Thursday, “following meticulous police work and a bit of police luck”, Rajt said.

The thief stole the skull just before mass on Tuesday evening when the alarm in the church was off, breaking the glass shrine and making away with the skull.

“He prayed to God that he would be alone in the church – and that’s what happened,” said Rajt. “But he was obviously so determined to commit the crime that there was nothing to stop him.”

Jan Ujka, a local detective, said the man pleaded guilty and was charged with offences including theft. He is now facing pre-trial custody.

Ujka that added the man, who has no previous criminal record, faces up to eight years in prison if convicted.