After four days of questioning over the 1972 murder of Jean McConville, and IRA membership, Mr Adams left Antrim police station by a rear exit as detectives passed a file on him to the Public Prosecution Service for decision on whether any charges would be brought in relation to the killing of the mother of 10.
Ms McConville’s son, Michael, said an outside police force should now examine the case.
Mr Adams was dismissive of what he called his “interrogation”, saying: “It was the old guard, using the old methods.”
Mr Adams said he had gone through 33 taped interview sessions, and had not eaten for the first two days of his arrest as the food was “indigestible”.
Mr Adams denied any involvement in the abduction and murder of Ms McConville, and said PSNI officers had accused him of IRA involvement since he was a child, adding he did not know if he would now face charges as a result of his arrest.
The Sinn Féin president said he supported the PSNI and there was no going back for the North, and the IRA was “finished”. However, Mr Adams insisted he had been held under a “pernicious” piece of legislation that should have been abolished, and said he had made a formal complaint about his detention.
The aftermath of his detention provoked strong reaction across the political spectrum.
Ahead of the release, Northern Ireland First Minister and DUP leader Peter Robinson accused Sinn Féin of adopting “bullyboy tactics” towards the PSNI.
Deputy First Minister Martin McGuinness insisted that the party still supported the PSNI.
“When I talked about reviewing our position in relation to policing, it was in the context of how we deal with this cabal within policing,” he said. “We are absolutely and totally supportive of the police services north and south of this border.”
Taoiseach Enda Kenny and British prime minister David Cameron discussed the situation for 10 minutes by telephone shortly before Mr Adams’ release and both leaders called for calm and the rule of law to take its course.
Former Fianna Fáil junior minister and adviser on the North, Martin Mansergh, claimed Mr Adams’s detention was part of a “classic British sting operation”.
The arrest caused global attention to focus on the North as details of the way Ms McConville was dragged from her children in west Belfast by a gang of up to a dozen after being wrongfully branded an informer, interrogated, shot in the back of the head, and dumped in an unmarked grave, were flashed around the world.
Head of the North’s Public Prosecution Service, Barra McGroy, relieved himself of any involvement in the decision on whether to charge Mr Adams, as he has acted as a solicitor for himt in the past.
When asked how it felt to be under arrest for so long, Mr Adams said: “It was OK.” He left the police station from the rear as loyalist demonstrators protested at the front gate.