A 27-year-old man was arrested in Londonderry as part of the investigation into the murder of journalist Lyra McKee.
The man, who was arrested under section 41 of the Terrorism Act 2000, was taken to Belfast for questioning.
A search of Derry’s home was also carried out, police said.
McKee, 29, was observing riots in the Derry’s Creggan area when she was shot on April 18, 2019.
A man, Paul McIntyre, 52, of Kinnego Park in Derry, has been charged with the murder of Ms. McKee.
He denies the accusation.