Who were the 'Disappeared'?
The IRA admitted in 1999 that it murdered and buried at secret locations nine of the so-called Disappeared.
Seven of these bodies have been confirmed as found but others remain missing.
Searches have been carried out by the Independent Commission for the Location of Victims' Remains, established in 1999 by treaty between the British and Irish governments to obtain information in strictest confidence which may lead to where the bodies are buried.
BBC News looks at the stories behind the Disappeared.
Eamon Molloy: Abducted from his home in the Ardoyne area of north Belfast in July 1975, after being accused by the IRA of being an informer. It was claimed he was quartermaster in one of the IRA's three Belfast brigades and that his activities forced the IRA into calling a ceasefire that year.
His body was discovered in a coffin left at Faughart graveyard near Dundalk, County Louth in 1999. after IRA intermediaries passed information to the commission for the location of the victims remains. 'Disappeared' victim identified
Brian McKinney: Twenty-two when he was abducted with his friend John McClory in 1978, he had first gone missing a few days beforehand, but returned 48 hours later, beaten and distraught. He had allegedly admitted to stealing IRA weapons for use in robberies.
His parents made him give back the money and it seemed the matter had been "resolved", but when he failed to return home from work soon after, his family began to fear the worst. His body was uncovered in a bogside location in County Monaghan in 1999. 'My tears for Brian'
John McClory: The 17-year-old was friends with Brian McKinney and went missing at the same time. His body was also recovered at the same site. Body finds encourage searchers
Jean McConville: The widowed mother-of-10 was killed in 1972. After numerous searches, the 37-year-old's remains were finally found at Shelling Hill beach in County Louth in August 2003.
Danny McIlhone: The west Belfast man went missing from his home in 1981. The IRA said Mr McIlhone was not suspected of being an informer but was being questioned about stealing weapons - it was claimed he was killed in a struggle with the person who was guarding him.
Remains discovered in the Wicklow mountains in November 2008 were confirmed as his. It followed two previous unsuccessful searches - in 1999 and 2000 - for his remains.
Charles Armstrong: The 57-year-old father-of-five from Crossmaglen in south Armagh, went missing on his way to Mass in 1981. His car was later found near a cinema in Dundalk. The IRA denied any involvement in his disappearance at the time. A team looking for Mr Armstrong found human remains in County Monaghan in July 2010. Two months later, the remains were confirmed as being those of Mr Armstrong.
Peter Wilson: Described as a vulnerable person with learning difficulties, he vanished at the age of 21 from his home in west Belfast in 1973. Reports suggest he may have been abducted and murdered by the IRA. His name was added to the list of the Disappeared in 2009 after new information became available.
For four days before he disappeared he lived with an Army unit at their headquarters near his Falls Road home. At the time the Army was accused of using a vulnerable person to gather information on the IRA, but the Army said they wanted him to experience military life.
His remains were found at Waterfoot beach in County Antrim in November 2010.
Gerard Evans: Last seen hitch-hiking in County Monaghan in March 1979, no-one has ever admitted responsibility for the 24-year-old's death. In March 2008, his aunt was given a map claiming to identify the location of his body. Mr Evans' remains were found at a site in County Louth in October 2010.
Eugene Simons: The 26-year-old went missing from his home near Castlewellan, County Down, on 1 January 1981. His body was discovered by chance in May 1984 in a bog near Dundalk, County Louth.
Kevin McKee: An IRA member, the Belfast man was alleged to have been a British army agent and member of its Military Reaction Force, an undercover unit. He was interrogated and murdered by the IRA in 1972.
Columba McVeigh: The 19-year-old from Donaghmore, County Tyrone was abducted and murdered by the IRA in 1975 after allegedly confessing to being a British army agent with instructions to infiltrate the IRA.
Extensive searches for his body were carried out in 2003 at a bog in Emyvale, County Monaghan, but nothing was found. His mother, Vera, was a tireless campaigner for the return of his remains - she died in 2007. Mother of Disappeared victim dies
A specialist forensic team spent five months in 2013 digging in a bog in County Monaghan for Mr McVeigh's remains, but found nothing.
Brendan McGraw: The IRA claimed that the 24-year-old from Belfast confessed to being a British provocateur and Military Reaction Force undercover agent in 1978.
Seamus Wright: The Belfast man was an IRA member, but in 1972 he was interrogated and murdered by his former colleagues who accused him of being a British army agent and a member of its Military Reaction Force.
Seamus Ruddy: The 32-year-old from Newry, County Down, was working as a teacher in Paris when he went missing in 1985. It is believed he was killed by members of the INLA. Fresh searches were carried out in 2008 after his family were told his remains were in a forest in Normandy, but they found nothing. Family of INLA murder man misled
Captain Robert Nairac: The SAS-trained officer was abducted by the IRA in Jonesborough County Armagh, in May 1977. The 29-year-old was abducted when he visited a pub at Dromintee, south Armagh. He had been in the pub singing rebel songs. He was seized during a struggle in the pub's car park and taken across the border to a field at Ravensdale, County Louth, and later shot dead. McGuinness in Nairac body appeal
Joe Lynskey: A former Cistercian monk from the Beechmount area of west Belfast, he later joined the IRA. Mr Lynskey went missing in 1972, and republicans have claimed Mr Lynskey was "executed and buried" by the IRA. Commission to probe Lynskey death