Sinn Fein northern chairman Bobby Storey and two other well-known republicans were taken into custody on Wednesday. They were released without charge on Thursday night.
But during the period they were being questioned by detectives, Stormont’s First Minister Peter Robinson stepped down and three of his Democratic Unionist ministers quit the Stormont coalition Executive.
The DUP mass resignation threat and subsequent walkout was prompted by the three arrests, amid claims the investigation into the shooting of former IRA man Kevin McGuigan had reached into the senior levels of Sinn Fein.
The Ulster Unionists pulled out of the Executive last month, claiming trust in Sinn Fein had been destroyed.
Commenting publicly on his arrest for the first time, Mr Storey said yesterday: “I absolutely reject the attempts of the unionist parties to cynically use these murders and my wrongful detention to threaten these political institutions.”
Police have said current members of the IRA were involved in last month’s shooting of Mr McGuigan in a suspected revenge attack for the murder of former IRA commander Gerard “Jock” Davison in Belfast three months earlier.
The disclosures about the IRA have heaped pressure on Sinn Fein to explain why the supposedly defunct paramilitary organisation is still in existence.
But Mr Storey added: “The behaviour of the unionist parties, who have cynically used my arrest to pull down the political institutions, has been nothing short of disgraceful.
“They have succeeded only in holding the political process to ransom and providing encouragement to the dissident elements and the criminals who murdered Jock Davison and Kevin McGuigan.”
Mr Storey said he had “serious concerns” over his arrest, and the timing of it and claimed “not a shred of evidence or intelligence” was presented to him during questioning.
But he backed the PSNI as the appropriate body to investigate the two murders.
“The people who murdered both men are criminals and enemies of the Sinn Fein peace strategy,” he said.
“Every effort must be made to ensure they are brought before the courts to face due process.” Intensive political talks aimed at saving power-sharing will convene in Belfast tomorrow.
There have been questions over whether unionists will attend the set-piece negotiations.
The Ulster Unionists confirmed they would be there “all things being equal”.
The UUP criticised a negotiation initiative last week for not scheduling the murder as the first item on the agenda.
The coalition government is teetering on the brink of collapse after the DUP last week pulled all but one of its ministers out of the administration.
Fresh talks involving the main parties and the British and Irish governments will be convened by Northern Ireland Secretary Theresa Villiers at Stormont House.
They will focus on the fallout from the murder and a range of other destabilising disputes threatening the future of the Stormont Executive, including the bitter impasse over implementing welfare reforms.
During an event in west Belfast yesterday, Mr Storey repeatedly insisted the IRA was no more - at one stage evoking the metaphor of a butterfly.
“I think the chief constable sees this in terms of the IRA being the caterpillar that’s still there, where I think it’s become a butterfly, it’s flew away.”