A cross-Border public inquiry is the only hope of getting to the truth behind the Omagh bombing, victims' families said last night.
Mr Michael Gallagher, whose son Aidan was killed in the explosion, said the families were devastated by the Court of Criminal Appeal's decision to quash the conviction of Mr Colm Murphy.
Mr Gallagher said relatives now felt like they were back to "square one" as no one had been brought to justice in the 6½ years since the "Real IRA" attacked the Co Tyrone town, killing 29 people, including a woman pregnant with unborn twins.
"We sat through a lot of that trial and it wasn't a nice place to be, but we felt glad walking out that someone was convicted for their part in the deaths of our loved ones," he said.
"Now we have to go through a retrial and face all that again, it is like being back at the bottom of a hill, and is very difficult for all of us. There must be questions that the court service, the Government and the Gardaí have to answer. It seems only a full public cross-Border inquiry will uncover the truth.
"We were always aware that you're at the mercy of the courts in situations like this, but we never expected this result.
"Here we are, 6½ years on and the only person convicted has won his appeal, so not one person has now been held accountable for an atrocity which claimed the lives of 31 people, including unborn twins.
"What sort of message does that send out to society that we can accept that number of people can be murdered and no-one can be brought to justice?"
After the hearing, Mr Murphy's sister, Ms Angela Reilly, said: "We are relieved . . . he is doing okay, better than three years ago when justice wasn't served." Mr Murphy's solicitor, Mr Michael Farrell, said: "The judgment speaks for itself."
The Labour Party justice spokesman, Mr Joe Costello, said the result of the decision was "that more than six years after the worst single atrocity in the history of the 30 years of violence, not a single person has been convicted.
"Intensive efforts by police forces on both sides of the Border have failed to deliver for the Omagh victims and their families."
The Republican Sinn Féin vice-president, Mr Des Dalton, said: "Republican Sinn Féin welcomes the Dublin Court of Criminal Appeal's quashing today of Colm Murphy's conviction and 14-year sentence by the non-jury Special Criminal Court.
"The fact that the non-jury Special Criminal Court was willing to convict Colm Murphy based on evidence which it is unlikely would have been accepted by a conventional court, as well as infringing his right to presumption of innocence, highlights the assault on basic human and civil rights which the non-jury Special Court and the draconian Offences Against the State Act represent.
"In its most recent observations on the 26-county State's human rights record in 2000," Mr Dalton added, "the UN Human Rights Committee called on the Dublin Government to dismantle the non-jury Special Criminal Court. Despite this, the Dublin Government announced in December that it intended opening a second non-jury Special Criminal Court."