A former British soldier who was arrested on suspicion of murdering three civil rights demonstrators in Londonderry on Bloody Sunday has been released on bail, police said.
The 66-year-old ex-paratrooper was detained by detectives from the Legacy Investigations Branch of the Police Service of Northern Ireland in Co Antrim on Tuesday morning.
He was the first person arrested by detectives probing the deaths of the 14 people killed after the Army opened fire on crowds of protesters in Derry's Bogside in January 1972.
The PSNI said: "A 66-year-old man arrested by Legacy Investigation Branch detectives investigating events of Bloody Sunday has been released on bail pending further enquiries."
It is understood the pensioner was arrested on suspicion of the murders of William Nash, 19, John Young, 17, and Michael McDaid, 20, all of whom were shot dead in close proximity to one another at a rubble barricade on Rossville Street.
It is believed the former soldier is also being questioned about the attempted murder of William Nash's father Alexander. Mr Nash came to the barrier to save his son but was shot in the arm and body.
It is understood the soldier gave evidence to the Government-commissioned inquiry into Bloody Sunday, undertaken by Lord Saville, under the cipher Lance Corporal J.
Thirteen people were killed by members of the Parachute Regiment on the day of the incident. Another victim of the shootings died in hospital four months later.
The PSNI's murder investigation into the events of Bloody Sunday was launched in 2012.
The probe was initiated after the Saville Inquiry found that none of the victims was posing a threat to soldiers when they were shot.
Following the publication of the Saville report in 2010, Prime Minister David Cameron apologised for the Army's actions, branding them "unjustified and unjustifiable".
In September, the PSNI announced their intention to interview seven former soldiers about their involvement on the day.