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A man who was arrested over a New IRA claim of responsibility for the shooting of senior detective John Caldwell has been released.
The 36-year-old man who was arrested on Tuesday morning, was released following questioning.
He was held as part of what police described as an ongoing probe into New IRA activities.
A typed message purportedly from the New IRA was posted on a Derry wall last month and said the group was responsible for Mr Caldwell’s attempted murder.
Police have said the New IRA is the main line of inquiry in the investigation.