By Vincent Kearney
Home affairs correspondent
More people were killed in the Omagh atrocity than any other during the Troubles
It was the worst atrocity of the troubles, but no-one has been convicted of the 29 murders in Omagh 10 years ago.
The chief constable has said he is frustrated that the killers haven't been caught, and admits it's now unlikely they ever will.
The police file on the Omagh bombing remains open, but Sir Hugh Orde is frank about the chances of securing a conviction.
"Unless we get a substantial new lead or perhaps a new witness stepping forward or someone confesses to the crime it is highly unlikely that you'll see the investigation reaching a successful conclusion in the sense of a criminal prosecution that leads to a conviction," Sir Hugh said.
"That doesn't mean there's any less determination to solve it, it means we need something new to investigate because what we currently have has been investigated to destruction."
Michael Gallagher, who lost his son Aidan in the explosion, finds it difficult to accept that those responsible haven't been caught.
"It's been an unbelievable catalogue of failures," is how he put it.
"There was a feeling that those responsible were going to be caught very shortly. I never thought I would be sitting talking about it 10 years after the event.
"And as far as justice is concerned, we're as far back as we were 10 years ago."
The hopes of the families of those who died were raised by firm statements of intent by the police and British and Irish governments in the immediate aftermath of the bombing.
Standing amid the rubble a shocked and angry Tony Blair had this to say: "People rightly expect that we will take whatever measures we can, properly and legitimately, to bring those responsible to justice."
Both governments introduced new laws aimed at making it easier to convict those suspected of involvement and Bertie Ahern, the taoiseach at the time, gave this pledge: "We will continue to try to bring the perpetrators to court and to lock them up for a very long time."
The police devoted huge resources to the investigation in its early stages and vowed that the killlers would be caught.
But the former Police Ombudsman Nuala O'Loan later published a damning critique of that investigation, accusing the police of letting down the victims and their families.
Sir Hugh Orde admits it is unlikely the killers will be brought to justice
Ten years on, no-one has been convicted of the murders. One man, Colm Murphy, was sentenced to 14 years for conspiracy to cause the explosion, but the conviction was later overturned and he's awaiting a retrial.
The only person charged directly with the 29 murders, south Armagh man Sean Hoey, was cleared of all charges last December.
His trial ended with the judge severely criticising the police, accusing two key prosecution witnesses of lying and labelling much of the evidence presented in court as useless.
Many of the families of those who died say they don't expect anyone to be convicted of the murders, and find it hard to accept.
Stanley McCombe lost his wife Anne in the blast. He said senior RUC officers visited him days after the explosion and told him they knew who was responsible.
He believes the police on both sides of the border do know the identities of the killers, but suggests there is no political will to put them in jail.
Sir Hugh Orde insists his officers did the best they could with what he calls "second-hand goods" from the initial investigation, and says they will continue to do all they can to catch the bombers.
But he understands the families' anger.
"I fully understand their frustration, because I think it's probably the same as my frustration," he said.
"They had an absolute right to have that crime brought to justice in the traditional sense and put through the courts and to see the people who committed that atrocity locked up and, literally, the key thrown away."
Some of the Omagh families are taking a civil action, suing five men they claim were responsible for the attack.
But they know it's highly unlikely that they'll ever see the people who bombed Omagh put behind bars.