A 69-year-old man has been released unconditionally after being arrested in connection with a pub bombing which killed 15 people.
The attack at McGurk's Bar in Belfast on 4 December, 1971, was carried out by the loyalist paramilitary group, the Ulster Volunteer Force (UVF).
The man was released after being detained at Antrim police station.
Police have recently reopened the case following a critical report into the original RUC murder investigation.
In the immediate aftermath of the attack, the IRA was blamed for placing the bomb.
In February 2011, the Northern Ireland Police Ombudsman published a report claiming the original Royal Ulster Constabulary (RUC) police investigation was "biased".
Following the publication, the Historical Enquiries Team, and more recently PSNI detectives in Serious Crime Branch, began a review of the case.
It is the second arrest in the reopened investigation in as many months.
In March, detectives arrested a 75-year-old man in east Belfast, but following questioning he was released unconditionally.
One man was convicted of all 15 murders in 1978.