The loyalist supergrass Gary Haggarty has been released from prison, with the families of his victims only learning of his release through media reports.
The former north Belfast UVF leader was sentenced to six and a half years just over three months ago for over 500 offences including five murders.
The BBC reports Haggarty has been released into a witness protection programme and taken to a secret location outside Northern Ireland.
He had spent more than four years in jail and lawyers for Haggarty had argued he had served his sentence.
The Public Prosecution Service (PPS) is currently appealing the sentence handed down to Haggarty.
Padraig O'Muirigh, a solicitor representing families of the victims of Haggarty, said they found out through news reports of his release and they were distraught although it was not a complete surprise to them.
"In their view Gary Haggarty is effectively a serial killer and in their minds treated more favourably than them," he told the BBC.
"It is very difficult for the families they have been through this very long process with the assisting offender trial we had and at the end of that we now have Mr Haggarty being released. And to rub salt in the wounds of the families we are 10 years after Nuala O'Loan's very critical report in relation to the police conduct and we have no police officer charged.
"It is fair to say they have lost an amount of faith in the justice process."
He said that while they were aware of the dates of his likely release "they did expect to be notified".
"To do it through the media first hand is a very cruel way to do it.
"Not that they would welcome it in any way. The way they have been treated today caused more distress and could have been handled better."
SDLP MLA Dolores Kelly said Haggarty's release should have been held until the PPS's appeal was heard.
Haggarty had been sentenced to 35 years in jail, however, given his guilty pleas and his agreement to become an assisting offender his final sentence was reduced significantly.
The former boss of the UVF’s notorious north Belfast Mount Vernon was a long-time police informer and pleaded guilty to a litany of serious crimes as his part of a controversial state deal that offered a significantly reduced prison term in return for giving evidence against other terrorist suspects.
The catalogue of offences stretch over 16-years from 1991 to 2007 and include the loyalist murders of John Harbinson, Sean McParland, Gary Convie, Eamon Fox and Sean McDermott.
As well as the five murders, Haggarty admitted five attempted murders, including against police officers; 23 counts of conspiracy to murder; directing terrorism; and membership of a proscribed organisation.
The loyalist pleaded guilty to a total of 202 crimes. The judge will also take into account 301 lesser offences committed by the paramilitary godfather.
The vast majority of individuals named by Haggarty in his police interviews will not face prosecution amid state concerns about a lack of supporting evidence.
Graphic details of Haggarty’s murderous confessions were outlined at a pre-sentence hearing last year, as were explosive claims that police failed to prevent loyalist murders despite receiving advance warning from their high-ranking UVF informant.
Families of Haggarty's victims said he was allowed to kill at will and expressed their dismay following his sentencing.
The Department of Justice said it would not comment on his release.