A man has been released after being questioned by detectives investigating the attempted murder of Detective Chief Inspector John Caldwell, in connection with the claim of responsibility made after the attack.
The man, 23, was arrested in Londonderry under the Terrorism Act on Thursday and taken to Musgrave serious crime suite in Belfast for questioning.
He was later released.
A PSNI spokesman said: “A file will now be submitted to the Public Prosecution Service.
“The investigation continues.”
Mr Caldwell was shot a number of times in front of his son at a sports complex in Omagh, Co Tyrone, in February.
The detective, who had investigated a number of high-profile murder cases, spent several weeks in intensive care.
A typed message, purportedly from the New IRA, was posted on a wall in Derry and said the group was responsible for the shooting.
Police have said the New IRA is the main line of inquiry in the investigation.
A number of people have previously appeared in court charged in connection with his attempted murder and on charges around the claim of responsibility.
