Sinn Fein leader Gerry Adams is still being questioned by detectives investigating the murder of Jean McConville.
Mr. Adams insists he had no part in the 1972 abduction and killing of the mother of 10.
Earlier, Minister Joan Burton described her killing as a 'war crime'.
The Social Protection Minister said Mrs. McConville was executed, saying 'her body was treated like that of a dog'.
Sinn Féin members have hit out at the timing of the move to detain Gerry Adams overnight - alleging it was politically motivated.
Minister Joan Burton told The Pat Kenny Show on Newstalk today that she wants to those behind the 'war crime' brought to justice.
Earlier the Sinn Féin Deputy leader Mary-Lou McDonald told Newstalk Breakfast that Deputy Adams retains her full support.
She insisted her party president is not a political liability, "Gerry is a duly elected, supported, respected leader of Sinn Féin".
International media await news of developments in the Adams arrest, Antrim PSNI station, as pictured by reporter Fergal O'Brien
Taoiseach Enda Kenny has responded to allegations from Sinn Féin on the timing of Mr. Adams' arrest.
Mrs. McConville was abducted and murdered by the IRA. Her remains were eventually found on a Louth beach in 2003.
The mother-of-ten is the most high profile of the "Disappeared", those abducted and killed during the Troubles.
Mrs. McConville (37) was taken from her home in front of her children and killed by the IRA after being accused of spying for the British army, claims later proven to be false.
No-one has ever been charged with the widow's murder.
Jean McConville's son, Michael, spoke to Newstalk in March about the night his Mother was taken.
Speaking this morning, her other son William welcomed the developments.
Boston college connection
Recent police activity in the case follows the decision of a US court to compel a university in Boston to hand over recorded interviews with republicans about the murder.
Boston College spoke to former paramilitaries about the Troubles, on the understanding the content of the conversations would not be published until after their deaths.
Veteran republican Ivor Bell was charged in March with aiding and abetting the murder. Five others have been questioned.