A trial at the non-jury Special Criminal Court has collapsed after it emerged the accused taped a conversation in which gardaí told him that his partner would be arrested and his child would go into care if he did not accept responsibility for other items.

Eimantas Valteris, 33, of Park Vale, Grange Rath, Drogheda, Co Meath, was arrested by gardaí in 2013 as part of an ongoing operation to counter dissident republican activities in the border area.

He was the first Lithuanian to stand trial at the Special Criminal Court.

The prosecution decision not to proceed with the trial came after the court heard a "voir dire" or trial within a trial.

During the voir dire, defence counsel Hugh Hartnett SC introduced the audio of a recorded conversation between Mr Valteris and two gardaí, one of whom was Detective Sergeant Padraig Boyce of the Special Detective Unit.

Det Sgt Boyce accepted under cross examination from Mr Hartnett that he was one of the two gardaí heard in the audio, which was recorded by Mr Valteris during an encounter he had with the two gardaí after his initial arrest.

During the playing of the audio in court, the gardaí were heard telling Mr Valteris that "we'll look after you" if he accepted responsibility for three other firearms and four silencers. The gardaí told him they knew the items were a "batch of four".

Mr Valteris was told that if he did not accept responsibility for the other items then the gardaí would be "directed" to arrest his wife. She had been in a particular premises collecting rubbish for about 30 minutes.

"If you don't take responsibility, she'll be next".

Mr Valteris was told by the gardaí that if his partner was arrested then their child would "go into care".

He was told that he was "digging a hole to put your missus" in if he wanted "to go down that route".

The gardaí told Mr Valteris that they knew he was "bullshitting", that they would "have to go to your house now and arrest your partner…She'll be in custody".

The gardaí were heard asking Mr Valteris: "Have we a deal or no deal … If we don't (have a deal) I'm going to have to arrest your partner".

On the fourth day of the trial, prosecuting counsel Mr Tony McGillicuddy BL told the three-judge court that the State was entering a "nolle prosequi" on the charge - in other words not proceeding with the prosecution - and Mr Valteris could be discharged.

Ms Justice Isobel Kennedy, presiding, ordered that Valteris should be discharged.