A Derry man has been found not guilty of possessing explosives, but a jury has been unable to return a verdict on whether he attended a terrorism training camp in Syria.
The panel was also unable to decide whether Eamon Bradley received training in the making or use of weapons for terrorism.
Northern Ireland's director of public prosecutions is expected to inform the court within a fortnight whether the he could face a retrial.
The 28-year-old denied six charges, including attending a rebel training camp in the Middle East war zone and receiving training in guns and grenades.
This was the first case of its type taken in Northern Ireland and it took the jury around six hours of deliberations at Derry Crown Court.
Mr Bradley was alleged to have been involved with a Syrian rebel group opposed to the regime and the so-called Islamic State group.
The "bedrock" of the prosecution case surrounded interviews he gave to police after he was arrested in Northern Ireland over images of him apparently posing with guns posted on social media.
He allegedly told a detective he was spirited into Syria from Turkey in a makeshift raft and joined the forces of the Army of Islam.
Mr Bradley is also said to have described being given months of training in using weapons before attending three battles as a junior soldier armed with a firearm and a grenade.
He denied firing a single bullet and allegedly returned home disillusioned after initially going to help the Syrian people.
Judge Brian Sherrard said Mr Bradley's defence had attempted to introduce doubts about the police interviews centring on his apparent lack of knowledge about military matters and about the Army of Islam.
Prosecutors said he was not a fantasist, and his account to police was the truth.
Mr Bradley is originally from Melmore Gardens in Creggan.
Bradley told police he signed up as a soldier in the rebel group in 2014.
He described, according to police notes of his interview, attending a training camp and carrying an assault rifle and grenade as a junior infantryman or mujahid fighter.
But he denied all six charges he faced.
An expert witness testified that the AK 47 assault rifles Bradley was photographed in front of could have been deactivated.
A lawyer for the defence said one of the battles the defendant told police he was present at did not happen.
According to earlier testimony he gave to police he used a Facebook page to research the fighting, convert to Islam and make contact with people who told him how to get there.
They pinpointed a village on the Turkey/Syria border and he said he was given a WhatsApp mobile messaging number to make contact with the rebels once there, according to interviews read out during the trial.
He allegedly flew from Dublin to Turkey in February 2014 then was smuggled across the border with Syria, crossing a river in a tractor wheel, according to the transcripts.
Bradley said he went to help the Syrian people.
A lawyer for the defence said it was a flimsy and threadbare case and there was no evidence to corroborate that he was even in Syria.
He said his client was not Derry's answer to Britain's First World War desert adventurer Lawrence of Arabia and was simply in Turkey on holiday.
According to the prosecution, he had truthfully agreed that he committed terrorism offences when questioned by detectives and was not a fantasist.
Barrister for the prosecution Ciaran Murphy QC said he was referring it back to the director of public prosecutions Barra McGrory QC.