Detectives investigating the murder of journalist Lyra McKee have arrested a 46-year-old man under the Terrorism Act.
A statement from the PSNI added that officers have also carried out searches at properties in the Northland Road and Creggan areas of Derry/Londonderry.
A number of items were also seized and taken for further examination.
Detective Superintendent Jason Murphy has made a fresh appeal for information to help the investigation.
“Since Lyra was murdered following violent disorder in Creggan in Derry/Londonderry on 18th April, our investigation has received widespread support from the community,” he said.
“I still want to hear from anyone who has any information and would appeal to the public to contact my team of detectives on 101.”
The gunman was aiming at police during disturbances in the Creggan when he hit McKee, who died in Altnagelvin Hospital in the city.
Dissident group the New IRA admitted responsibility for her murder in a statement given to The Irish News using a recognised code word. The group offered “full and sincere apologies” to her family and friends.