Deemed one of the most dangerous men in Northern Ireland, dissident republican Martin Corey was ushered out a side-door of Maghaberry Prison to freedom.
Corey, from Lurgan, Co Armagh, is a convicted double-murderer, having been involved in the IRA killing of two police officers in 1973.
He was released on licence in 1992.
His return to prison in 2010 sparked a four-year legal battle, with Corey's imprisonment the subject of ultimately unsuccessful hearings at High and Supreme Court level.
The decision by the Parole Commissioners to set him free follows the rejection of those courtroom appeals.
Life sentence prisoners remain on licence for life.
There may be specific conditions attached to a licence designed to manage any particular risk posed by the individual who has been set free.
In the vast majority of cases prisoners on licence are subject to the condition that they must not pose a risk of harm to the public.
They are liable to be recalled to prison if they breach the conditions of their licence or pose a risk of harm to the public.
It was first recommended to revoke Corey's licence on April 14, 2010 when Shaun Woodward was Secretary of State, and Corey was placed in prison.
Before the Secretary of State can revoke a licence of this type they first seek a recommendation from the independent Parole Commissioners.
The Parole Commissioners consider the information available, which may include information indicating that the individual is in breach of their licence, before deciding whether or not to make a recommendation that the individual be recalled to prison.
If the commissioners consider that the individual poses a risk of serious harm to the public they will recommend that the individual be returned to prison and the Secretary of State may then revoke the licence. The individual is then returned to prison.
The Parole Commissioners provided this recommendation in respect of Corey.
The Parole Commissioners then review the case in full.
The Parole Commissioners issued their first decision, which was not to release him due to a risk of harm to the public, on August 16, 2011.
At the time they said they were satisfied he was a leading member of the Continuity IRA from 2008 until he was placed in prison, having been involved with the group since 2005.
Their decision on the most recent review of the case, to release him on licence with conditions attached, was issued on Wednesday.
The prisoner has legal representation throughout and can challenge the case against them.
If confidential material – in other words, material which can't be shared in full with the prisoner – forms part of the case against an individual, the prisoner must be provided with a summary of the allegations and a special advocate chosen by the prisoner's legal team is appointed to represent their interests.
Throughout his time behind bars – described as internment by his supporters – Corey claimed he was unaware of the allegations against him.
The Northern Ireland Office yesterday denied that claim, insisting Corey was fully informed of the authorities' concerns and the reasons for taking him off the streets.
In July last year Corey won a judicial review against the decision to keep him behind bars, but in December the Supreme Court said the High Court did not have the jurisdiction to direct his release. It was as a result of a review of his case that the Parole Commissioners decided that the risk posed by Corey had sufficiently reduced for him to be released on licence, with conditions attached which were designed to address the specific risk they considered he might pose.
The Parole Commissioners' ruling on whether the prisoner posed a risk of harm to the public was made on the basis of information presented on behalf of the Secretary of State and the prisoner.
The decision of the commissioners cannot be overruled by the Secretary of State.
However, if Corey breaks the conditions of his release as set down by the commissioners a bid can be made to return him to prison.
In a statement following his release, supporters of Corey said: "Martin was interned on secret evidence gathered by secret police and held without a charge or trial since April 2010.
"The British Government, Secretary of State and all those involved in the internment of Martin Corey showed contempt for human rights and were involved in a despotic policy of ruling by decree.
"We would like to thank everyone who was involved in the Release Martin Corey Campaign, Republican Sinn Fein, the countless activists who stood on picket lines and those who went to jail themselves to highlight Martin's case."
Corey's release came on the same day detectives outlined details of a huge investigation currently under way into dissident republican terror activity.
Detectives said they are monitoring a number of men active in terror cells across Northern Ireland and across the border.
Police are investigating a number of off-shoots of a central dissident gang, comprising around 20-25 individuals in total, and based in Omagh, Coalisland, Toomebridge and Ballyronan on the northern shore of Lough Neagh, as well as Monaghan in the Republic.
Investigators have linked the murder of young Catholic police officer Ronan Kerr to 16 other crimes committed by the inter-connected dissident republican umbrella group.
The 25-year-old was killed by a booby-trap car bomb explosion at his Omagh home in April 2011.
Among the incidents by the self-styled new IRA – directed by its Belfast leadership – were two failed murder bids that seriously injured two police officers, including Peadar Heffron, and a car bomb attack on the Policing Board in Belfast.
Police said the investigation could last for up to five years.