Prominent republican Colin Duffy - one of six suspects held over security force murders in Northern Ireland but released today after a high court challenge - has been re-arrested, his lawyer said.
The Lurgan man's solicitor Pat Vernon said his client was taken back into custody under anti-terrorism legislation.
Only an hour earlier, a Belfast judge overturned a court order granting the police further time to question the suspects over the murder of two British soldiers and a policeman this month.
Outside Antrim police station, Mr Vernon said: "We understand he has been re-arrested under Section 41 of the Terrorism Act again, but we don't know any further details."
The lawyer said his client's continuing detention was unlawful.
The other five suspects, freed after the ruling, were driven out of Antrim police station at high speed with coats over their heads.
Colin Duffy came to prominence in the 1990s when he was acquitted of the murder of a soldier after it emerged a key witness was a loyalist paramilitary.
He was subsequently charged over the murder of two police officers, though that case collapsed.
In a statement issued today by Duffy's family they said police were effectively disregarding the court ruling.
They said: "Colin has previously been the victim of persecution by the state and its forces which included previous periods of imprisonment which were proven to be completely unjustified."
The family added: "We call for his immediate release and are appealing to all those interested in justice to support us in our campaign to return Colin safely home to his wife, children and wider family."
Four of the six people arrested by police were being held in connection with the shooting of Sappers Mark Quinsey, 23, from Birmingham and Patrick Azimkar, 21, from London, outside an Army barracks in Antrim on 7 March.
Two other soldiers and two civilian pizza delivery men were seriously wounded in the shooting, responsibility for which was claimed by the Real IRA.
The other two were being questioned over the death two days later of Police Service of Northern Ireland (PSNI) Constable Stephen Carroll, 48, in the Co Armagh town of Craigavon.
The Continuity IRA claimed this killing.
A 17-year-old youth and a 37-year-old man have already been charged with the policeman's murder.
After today's developments police said they were continuing to investigate the killings.
A PSNI spokesperson said: "This remains a live and active major investigation and detectives are following a number of definite lines of inquiry."
The suspects had been held since 14 March, and at the weekend a judge granted a police application to have their detention extended for a further seven days as they were still awaiting the results of potentially vital forensic tests at the crime scenes.
Their lawyers challenged this extension and today Northern Ireland Lord Chief Justice Sir Brian Kerr quashed the original ruling on a legal technicality.
He ruled that judge Corinne Philpott, while making her deliberations, had not taken into account whether the suspects' original arrest had been lawful.
Sir Brian did not question the lawfulness of those arrests but said the judge who granted the extension should have examined the issue.
On that basis he upheld the defence team's claim that the decision should be reversed.
Sinn Fein has called on the public to support the police investigations, with Deputy First Minister Martin McGuinness branding the killers traitors determined to undermine the peace process, despite public support for the current political arrangements.
But the party's president Gerry Adams called on the police to charge or release the suspects and today he welcomed the court decision.
Mr Adams said: "Detaining people for periods extending beyond human rights best practice is simply not acceptable and must not happen in the future.
"I welcome the ruling of the High Court this morning. This case should never have had to arise. Our position has been made very clear both publicly and privately to the British Government and the PSNI.
"If evidence does exist against an individual, then that person should be charged and that evidence tested before the courts.
"If no such evidence exists, then that person should be released."
The Northern Ireland Office said today the authorities remained committed to pursuing the investigations.
Policing and Justice Minister Paul Goggins said: "The attacks in Northern Ireland are the subject of strong and ongoing police investigations.
"Two people have already been charged with the murder of Pc Stephen Carroll and the work by police to investigate this murder continues.
"Today's High Court ruling is, of course, in relation to a technical issue around detention and the law has taken its course on this specific aspect of the legal process.
"Nonetheless, the police investigation into the murder of the soldiers at Massereene Barracks and the attempted murders of two other soldiers and two civilians are ongoing.
"The determination of the police to carry out their investigation thoroughly, comprehensively and with the support of the whole community continues."
At the High Court, the Lord Chief Justice quashed the decision to allow the further detention of the suspects.
Sitting with Lord Justice Malachy Higgins and Lord Justice Patrick Coghlin, Sir Brian considered four grounds of challenge and concluded that the judge was wrong on one of these, in that she did not review the lawfulness of the arrests.
He said the powers of the Terrorism Act 2000 had to be read against the European Convention on Human Rights (ECHR), forcing a review of the lawfulness of detention and examining the basis for arrest.
He said: "If it were otherwise, a person could be detained under the Act for up to 28 days without there having been any judicial review of the lawfulness of the original arrest and that, in my view, could not be compliant with article five of the ECHR."
Mr Goggins said the court ruling was based on a technical issue and did not call the anti-terror legislation into question.
Head of the Northern Ireland Human Rights Commission Monica McWilliams sparked controversy yesterday by criticising the conditions that the suspects were being held in at the serious crime suite of Antrim police station.
Professor McWilliams said the holding centre had been designed for detaining suspects for shorter periods than the 28 days allowed under the current legislation.
But Northern Ireland chief constable Sir Hugh Orde said he had visited the station and declared that he believed it was fit for purpose.
A solicitor for those being questioned again hit out today at the conditions in the Antrim holding centre.
After news of Duffy's re-arrest, Sinn Fein Policing Board member Alex Maskey said the Lurgan republican should be released or charged.
Mr Maskey said: "This afternoon's re-arrest is a clear abuse of the court's judgment.
"Sinn Fein has made our position in relation to all of this very clear. Human rights best practice must be stringently adhered to at all times, with people being either charged or released.
"The PSNI must be seen to operate to the highest standards of human rights compliance in order to ensure public confidence in due process."