The day of the Omagh bombing is one of those you tend not to forget. I was off work and had been out with my family when I received telephone messages from The Sunday Times saying there had been an explosion in the Tyrone town with up to eight people dead. Could I come in and find out what I could?

I wondered if there had been some mix-up. I’d lived in Omagh for years, finishing school there, and it was as pleasant a town as you could imagine with little sectarian tension. People tended to get on.

By then the IRA was on ceasefire and the Troubles were over. Even the weather was unusually good, but that served only to increase the number caught in the blast. The death toll was 29 plus two unborn babies. Another man was killed by an ambulance speeding away from the scene. It was the biggest atrocity of the Troubles and the worst mass-murder in British and Irish history.

At the time the massacre seemed like a possible tipping point which could reignite the violence by pumping new bitterness into the community. In the event it seemed to have the opposite effect — the attack was so indiscriminate, touching all sides of the community in a mostly nationalist town, that reprisal or revenge made no sense even to the twisted logic of loyalist paramilitaries.

Michael Gallagher, the leader of the Omagh Support and Self Help Group, said last Friday that we didn’t expect to be talking about this 10 years later; we expected the guilty to have been caught and convicted. We expected closure.

At first Bertie Ahern and Tony Blair talked of leaving no stone unturned and the RUC and gardai made the right noises about their investigations. They were on top of the case and appealing for evidence. Much was made of new forensic methods. Teams of detectives were brought in from other forces to help sift mountains of debris. They were able to reconstruct the timer and power unit that had detonated the device and Eric Anderson, the detective initially in charge of the investigation, was able to explain precisely the sequence the bombers went through.

Listening to the Real IRA’s excuses brought to mind a few lines of From the Irish, a poem written by my old teacher James Simmons years earlier:

“Familiar things, you might brush against or tread upon in the daily round, were glistening red with the slaughter the hero caused, though he had gone. By proxy his bomb exploded, his valour shone.”

One photograph from the time illustrates the underlying flaws in the investigation, however. It shows a detective in face mask and protective clothing, like a surgeon, examining debris through a magnifying glass. Sir Ronnie Flanagan, the RUC chief constable, is leaning over the detective’s shoulder for a better look. He wore a suit and tie with no covering on his face.

At the time there was no thought of extracting the minute quantities of DNA which the forensic science laboratory in Birmingham now uses but, even by the standards of the day, the RUC procedures were slipshod. In acquitting Sean Hoey, who police believe made the timing and power unit, Justice Weir accused two officers of lying about whether they had worn protective clothing; described procedures as “thoughtless and slapdash”; and said that storage facilities at the forensic science laboratory were “a complete mess”.

Relatives’ confidence in the investigation were further undermined when Kevin Fulton, a PSNI agent, claimed to have warned his handler about a Real IRA bomb shortly before Omagh. Nuala O’Loan, then police ombudsman, found that Fulton’s warnings would not have prevented the attack, but accused the police of poor leadership and of failing to follow up evidential leads.

To be fair to the police, for a few years after the bombing Sinn Fein would not encourage people to co-operate. With witnesses being sought in republican heartlands such as South Armagh, this attitude dealt a serious blow to the investigation.

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