One of the ‘Colombia Three’ looks set to have an IRA weapons conviction dating back 30 years overturned in his absence after it emerged that vital evidence was not seen by the original trial.

Martin McCauley (51) can be arrested if he steps foot back in Northern Ireland on an outstanding international arrest warrant that would see him extradited to South America to serve a 17-year jail term.

Along with two other men, Niall Connolly and James Monaghan, he was arrested in Colombia in 2001 and accused of training guerrillas of the Revolutionary Armed Forces of Colombia (Farc).

In 1982 McCauley was shot and seriously wounded by an undercover RUC team in a farm shed near Lurgan.

His friend Michael Tighe (17) was killed by officers who had staked out the shed.

McCauley, from Lurgan, received a two-year jail term that was suspended for three years for possession of three rifles discovered in the shed.

The killing was one of six so-called shoot-to-kill cases investigated by John Stalker, who had served as assistant chief constable of Greater Manchester Police.

He was removed from the inquiry in disputed circumstances but later revealed in his memoir that, unknown to the RUC men involved, the entire incident had been secretly recorded.

“An electronic bug, installed by MI5, had been operating, concealed in the rafters, throughout the entire police assault on the barn,” Mr Stalker said.

“No-one in the security services or police could ever have possibly imagined that its use was to become known to the world, when one day, by accident, it eavesdropped on death.

“This tape has become a rope in a bitter tug-of-war between those who believe the method of intelligence gathering should be protected at all costs.”

The secret recording was never made available to the defence or shown to the judge in McCauley’s original trial.

Police who gave evidence confirmed they were encouraged to make false statements to protect a source.

They admitted not entering the barn after seeing a gunman as claimed but had instead been directed there by colleagues in Special Branch.

In 2005 McCauley made an application to the Criminal Case Review Commission, set up to examine miscarriages of justice.

It has now referred the case to the appeal court, referring to “information obtained by the commission that was not known by the trial judge and that, in the commission’s view, raises a real possibility that the Court of Appeal will now quash the conviction”.

Mr McCauley’s solicitor, Fearghal Shiels of Madden & Finucane, welcomed the decision.

“It is clear that the entire events which took place in the hayshed were monitored by the RUC,” he said.

“The existence of the tape and the vital evidence it contained was concealed from the defence and the judge who heard Mr McCauley’s trial.

“Given the conflicting accounts of the police on the one hand and the accused on the other of the events in the hayshed it is difficult to imagine a more crucial piece of evidence.”

Incident threatened peace process

The high-profile case of the ‘Colombia Three’ threatened to the destabilise the peace process a decade ago.

Jim Monaghan, Martin McCauley and Niall Connolly fled Colombia to escape imprisonment in 2004 after the IRA, which was on ceasefire, was accused of providing explosives training to left-wing rebels.

They were initially cleared of training the Farc group but found guilty of travelling on false documents and illegally entering the country.

The Colombian government appealed the ruling and the three were convicted of assisting terrorists and sentenced to 17 years in jail.

How they managed to escape the South American country remains clouded in secrecy but the three resurfaced in a public appearance in the Republic in August 2005.

An extradition warrant was granted in Northern Ireland but not the Republic where the men are believed to be.

Monaghan, from Co Donegal, was previously jailed for IRA offences while Connolly, from Co Dublin, was a Sinn Fein representative in Cuba.

There is no extradition treaty between Colombia and the Republic.