SF on rack as Adams held for second night
* Backlash over Mary Lou's political interference claim
* McConville son: my life is in danger if I name mum's killer
The party is in crisis on both sides of the Border after Mr Adams was held in police custody for a second night, facing questions about the abduction and murder of widowed mother-of-10 Jean McConville.
Her son Michael admitted that he is still too afraid to tell police the identity of his mother's killers for fear that the IRA will take revenge.
Chillingly, the family told how they are still haunted by her screams as their mother was torn away from them more than 40 years ago.
"Everybody thinks that the IRA has gone away but they have not. If we tell, we will be shot," said Mr McConville.
A political crisis erupted as news of Mr Adams's detention spread, with the North's Deputy First Minister Martin McGuinness claiming "dark forces" had a role.
Sinn Fein politicians at Leinster House privately admitted that the extraordinary events could halt the party's anticipated breakthrough in this month's local and European elections.
Mr McGuinness and Ms McDonald both alleged that the timing of Mr Adams's arrest was designed to clash with campaigning.
"I view his arrest as a deliberate attempt to influence the outcome of the elections that are due to take place in three weeks' time, North and South on this island," Mr McGuinness said.
Mr Adams (65) strongly denies any involvement in the abduction and murder of Mrs McConville, who was 37 when the crime took place in 1972. She was dragged from her home by an IRA gang after being accused of passing information to the security authorities. Her remains were found in Co Louth in August 2003 – more than 30 years later.
Mr Adams can be held until tonight, by which time police must release or charge him or seek a judicial extension to his custody.
He is being questioned largely regarding claims made in the so-called Boston Tapes, although police sources said the arrest followed additional intelligence being brought to the attention of the PSNI.
It is believed a number of recent newspaper reports were presented to Mr Adams during his questioning yesterday.
Investigators initially had 24 hours to quiz him but at 8pm last night a senior police officer gave permission for an additional 24 hours of questioning.
As the Sinn Fein leader was being interviewed in Antrim police station, party colleagues faced a series of bruising media appearances.
Ms McDonald at times struggled to maintain her composure as she defended Mr Adams's past. The Dublin Central TD said members of the "old guard" within the PSNI and elements of the unionist movement had "politically coalesced" to ensure the arrest ahead of elections in three weeks' time.
She insisted that Mr Adams was not "a suspect in a murder case" and claimed that his arrest was "calculated and politically motivated".
Ms McDonald also accused journalists of trying to coerce her into using the word "murder" to describe what happened to Mrs McConville, as she brushed aside any suggestion of doubt about the future of Mr Adams's leadership of the party.
"I would use the word 'death', 'killing', 'murder', whichever. The woman lost her life in the most appalling of circumstances and an appalling injustice was done," Ms McDonald said.
Some of Sinn Fein's candidates took a break from the campaign trail yesterday as the controversy engulfed the party.
Three European candidates – Matt Carthy in Midlands-North-West, Liadh Ni Riada in Ireland South, and Lynn Boylan in Dublin – said they believed Mr Adams when he said he was never a member of the IRA.
Ms Ni Riada told the Irish Independent that she "absolutely" believed that Gerry Adams was never in the IRA.
"This is something that happened over 40 years ago and the reality is, to the people on the ground, they're more concerned with more pressing issues, such as trying to put food on the table and keep a roof over their heads," she said.
Ms Ni Riada also said that you would have to "be naive to think it was not politically motivated".
But the Taoiseach, British prime minister and Stormont First Minister all dismissed the Sinn Fein claims.
The Taoiseach said he hoped Mr Adams would give all co-operation to the PSNI. "This is a murder case which has not been solved and no one has been brought to justice.
"Deputy Adams has been arrested. The real victims here are the family of the late Jean McConville. She was murdered and her murder has not been solved," Mr Kenny said.
British Prime Minister Mr Cameron said there had been absolutely no political interference. "We have independent policing authorities, independent prosecuting authorities. Those are vital parts of the free country and the free society we enjoy today."
Mr McGuinness spoke by phone to Mr Cameron to challenge him on the issues of state killings. "I know that some investigations are pursued more vigorously than others," he said, referring to mass killings attributed to the security forces. "British forces are protected and immune."
"It strengthens our political process in Northern Ireland for people to know that no one is above the law, everyone is equal under the law and everyone is equally subject to the law."
Mr Adams's arrest follows the charges brought against veteran republican Ivor Bell (77) in March for allegedly aiding and abetting the murder. He is awaiting trial and is expected to contest the charges.
Mr Adams contacted police more than a month ago to inform them that he was willing to discuss Mrs McConville's disappearance. "If the PSNI wish to talk to me on this matter I am available to meet them," he said at the time.