An elderly man has been arrested by police investigating a Belfast pub bombing that killed 15 people.
The attack at McGurk's in the city in 1971 happened as the conflict began to deepen and victims' relatives have spearheaded a long-running justice campaign.
The 75-year-old man was detained in East Belfast after the PSNI reopened its investigation.
Detective Chief Inspector Justyn Galloway said: "Despite the passage of time, there remain a number of opportunities to make progress.
"We will do our best to develop these lines of inquiry as thoroughly and quickly as possible.
"At the same time, I would ask those individuals who know who was involved in this attack on 4 December 1971 to talk to us.
"Much has changed in the four decades since this terrible atrocity but the families of the victims and survivors continue to suffer."
The attack was carried out by loyalist paramilitary group the Ulster Volunteer Force (UVF), even though in the immediate aftermath of the attack the IRA was blamed for planting the bomb.
In February 2011, the Northern Ireland Police Ombudsman published a report which said the original Royal Ulster Constabulary investigation was biased.
Later the independent Historical Enquiries Team of detectives, which is investigating more than 3,000 unsolved conflict killings, and more recently the PSNI reviewed the case for new leads.
In 1978, UVF member Robert Campbell was convicted of the murders and attempted murders of those in McGurk's Bar.