A 40-year-old man who was questioned by police in connection with the death of a prison officer in Belfast last year has been released.
Adrian Ismay, 52, suffered serious leg injuries when a bomb exploded under the van he was driving last March.
He died in hospital 11 days later.
Detectives from the PSNI's Serious Crime Branch arrested a 40 year-old man this morning.
He has since been released pending a report to the Public Prosecution Service.