A Specialised Court in Medellin, Colombia's second city, yesterday heard evidence against Mr Jim Monaghan, Mr Martin McCauley and Mr Niall Connolly. The Irishmen were arrested as they tried to leave Bogota airport in August 2001.
They are accused of entering the country with false documents, and the more serious offence of training leftist rebels from the Revolutionary Armed Forces of Colombia, or FARC, in bomb-making techniques. If found guilty, they face up to 20 years in prison.
The three men have sent communiques to the court in Bogota, the country's capital, before each of the pervious hearings, saying they would not appear at their trial.
In December, during a two-day session of the trial at the Specialised Court - the Colombian equivalent of the Special Criminal Court - Judge Jairo Acosta ruled that one of the prosecution witnesses, Mr John Alexander Caviedes, could give evidence in Medellin where he is now living.
Mr Caviedes (19) claimed at yesterday's hearing that he was a member of the FARC from 1997 to 2000 and that he was the driver and bodyguard of Mr Fabian Ramírez, one of the senior commanders in the organisation.
Mr Caviedes is currently on a re-insertion programme for former guerrillas. In December he sent a fax to the Bogota court saying that as a FARC deserter he feared for his life if he travelled to Bogota by road.
At yesterday's hearing he said he drove "foreigners" around the former demilitarised zone controlled by the FARC, but gave vague descriptions of the accused. He also claimed to have received training in bomb-making and mortar assembly from three men whom he was told: "belonged to a revolutionary group in Ireland". Just before the hearing ended at 3:15 p.m., Mr Caviedes turned to the prosecuting lawyer and said: "I would just like to say that I have more evidence that might interest you, but the only thing that I am asking for in return is more protection for my life.
"The evidence I have is a video and photos of the training sessions given by the three men." The prosecution lawyer said he would request a place for Mr Caviedes on the state witness protection programme.
Members of Colombia's two main guerrilla groups who voluntarily give themselves up are normally placed on re-insertion programmes in different parts of the country. Over the years many deserters have been killed.
The three Irishmen claim they cannot get a fair trial in Colombia and that the case has become politicised and is tainted by declarations from high-ranking Colombian government officials.
Ms Caitríona Ruane, spokewoman for the Bring Them Home solidarity campaign, said the case should be dropped.
"The testimony of Caviedes is riddled with inconsistencies, it is obvious why the authorities didn't want this witness to be heard in Bogota".
She added, "we are calling on the Irish government to call a halt to this farce and to stand up for the rights of Irish citizens. There is no justice for the three men.
"It is time that the Irish government stopped pretending that they can get a fair trial and that Colombia is a democracy."
Accompanying Ms Ruane at yesterday's hearing was Dublin solicitor, Mr Pat Daly, who was acting as an observer, and Ms Deirdre Farrell from the Irish Embassy in Mexico on behalf of the Irish Government.