Case crumbled as evidence of convicted fraudster began to fall apart
The case against Seamus Daly hinged on a mobile phone and the evidence of a convicted fraudster.
The signals of two mobile phones, believed to have been used by the bombers, charted their movements on the day of the atrocity.
Phone mast evidence tracked the pair as they crossed the border and arrived in Omagh at 2pm on August 15, 1998 - around 20 minutes before the bombers parked their car and primed the bomb.
A builder from Kilkenny, Denis O'Connor, claimed to have received a phone call from one of the phones at 3.30pm, some 20 minutes after the bomb had exploded.
He said that the caller was Seamus Daly.
For the Public Prosecution Service (PPS), Mr O'Connor's evidence placed one of the bomber's phones firmly in the hands of Daly during the bomb run.
Mr O'Connor, who has a conviction for tax fraud, became the prosecution service's star witness.
However, as soon as he took to the stand to give evidence during a pre-trial hearing last week, the case against Daly began to unravel before it even really got started.
The hearing was to allow a district judge to decide if there was enough evidence to return Daly for Crown Court trial.
Under intense cross-examination, Mr O'Connor admitted that the call he believed was from Daly may actually have been received a week before the bombing.
Further questions also arose over his reliability as a witness when he contradicted himself over whether or not he had ever met another man successfully sued for liability for the Omagh bomb - Dundalk-based publican and building contractor, Colm Murphy.
These flaws in the evidence of the PPS's key witness undermined the case against Daly so badly that a decision was taken not to continue with the prosecution.
It is understood that the PPS was aware of some of the discrepancies in Mr O'Connor's evidence six days before the preliminary hearing.
However, they believed he was still a reliable witness, given that he had given evidence at the successful civil case.
But after reviewing 173 pages of Mr O'Connor's court deposition over recent days, Director of Public Prosecutions Barra McGrory decided that the evidential test for prosecution was no longer met.
The case crumbled before it even hit the Crown Court.