In the hearing of the appeals plea from Michael Campbell, who has been sentenced to 12 years, the Vilnius court decided on Thursday that testimony from another Irish citizen, Brendan McGuigan, was also necessary in the case. Both Campbell and McGuigan are suspects in a another investigation and are currently litigating for extradition to Lithuania.
"The court will take measures to have the two individuals interrogated," judge Viktoras Kazys said on Thursday.
Last year, a Vilnius court sentenced Campbell to 12 years in prison for assistance to a terrorist group, possession of firearms and attempts to smuggle them. He was detained in January of 2008 after purchasing arms from an undercover agent.
The Court of Appeals noted that Campbell had been convicted for the deeds performed in a criminal group; however, other potential participants were never interrogated.
The convict's brother Liam is listed as one of the key leaders of Real IRA and has been found responsible for 1998 bombings in Omahg, Northern Ireland, which killed 29 and injured more than 200.
Lithuania's law-enforcement is waiting for a decision on his extradition to Lithuania. "The extradition process is in progress, it is in its first instance and is yet to be completed. As far as I know from my colleagues, the procedure is in process in Belfast," Campbell's lawyer Ingrida Botyrienė told BNS.
The second suspect, McGuigan, is currently in the Republic of Ireland, and his extradition procedure is also yet to be concluded.
"The only possible way to interrogate them is to question them via competent institutions in the locations they are at now," said the lawyer.
She said the court's step was logical, adding that prosecutors should have made the move during the pre-trial investigation.
The prosecutor had asked the court to increase the sentence to 16 years but the Vilnius court sentenced him to fewer years, saying the Irishman's actions were under control of security officers and no actual damage was done.
At a court hearing in August, prosecutors cited secret witnesses as saying that Campbell had asked what amount of explosives was needed to blow up a government vehicle and said he planned to use the weapons against people.
Campbell pleaded not guilty, saying he had been provoked by British security agents.
The Real IRA is a paramilitary organization that strives towards a united Ireland. Under Irish laws, Real IRA is an illegal organization, which the Council of Europe has listed as being related with terrorist attacks.
