A 73-year-old man was released unconditionally after being questioned by detectives investigating the murder of Jean McConville.
Police arrested the pensioner in the Dunmurry area yesterday.
He was taken to Antrim Serious Crime Suite for questioning.
The man was released unconditionally later in the afternoon.
The 1972 abduction, killing and secret burial of mother-of-10 Mrs McConville was one of the most notorious crimes of the Troubles.
The police case lay effectively dormant for decades until a flurry of activity this year, with a series of arrests made, the most high-profile being the four-day detention of Sinn Fein president Gerry Adams.
Mr Adams, who vehemently denies involvement, was released pending a report being sent to prosecutors for assessment.
Mrs McConville was dragged screaming away from her children in Divis flats in west Belfast by a gang of up to 12 men and women after being wrongly accused of giving information to the security forces.
She was interrogated, shot in the back of the head and then secretly buried - becoming one of the Disappeared victims of the Troubles.
Her body was not found until 2003 on a beach in Co Louth, 50 miles from her home.