Police in Saudi Arabia arrested a man in the eastern city of Qatif after he opened fire on a security patrol, state-run Al Ekhbariya TV said on Tuesday, adding that he was wanted for robberies on vehicles transporting cash.
The man, Mohammed Hussein Ali Al Ammar, was described as the "most dangerous wanted terrorist", Al Ekbariya said.
He is suspected of being involved in the kidnap and murder of a judge and participating in a fierce gun battle with police that killed one officer and wounded another. No further details of the shootout were provided. He also opened fire on a separate police patrol near a mosque in Qatif.
Judge Sheikh Mohammed Jirani was kidnapped in 2016 after being taken in front of his home in the eastern province of Awamiya.
Sheikh Jirani's remains were found on a farm in the area in 2017.
The judge was the target of a number of attempts on his life before his abduction.
Sheikh Jirani was critical of fellow Shiites in the kingdom and had accused some clerics of being too close to Iran.
Mr Al Ammar, along with Maitham Ali Mohammed Al Qudaihi and Ali Bilal Saud Al Hamad, were linked to the kidnapping.
The three are on kingdom's most-wanted list alongside six others.
Mr Al Ammar is also suspected of throwing Molotov cocktails at government buildings in Qatif.
The arrest comes less than two weeks after two men driving a car laden with explosives were killed in a shootout with police in the eastern city of Dammam.