A 21-year-old former private Sydney school student has been arrested in Bulgaria on terrorism charges and faces eight years in jail if convicted.
John Zakhariev has been in custody since September, at the foreigners' wing of the maximum security prison in Sofia, in the Eastern European country's capital.
Bulgarian authorities allege he attended shooting ranges, kept "jihadist material" and tried to join a terrorist group in Syria four years ago to fight, but was rejected due to lack of combat experience.
But the family of the Waverley College catholic school graduate believe he is being made an example of for crimes he did not commit.
Mr Zakhariev is the son of a Vietnamese-Australian mother and a Bulgarian-Australian father.
He converted to Islam during high school but reverted to Christianity mid-last year, he told Bulgarian media.
In the interview, he said he was distressed by the stories of those affected by the tragedies in Syria and "I wanted to go to see what the situation was, to see what I could do to help the Syrian people."
The young man's lawyer Hristo Botev told Fairfax Media Mr Zakhariev joined Sydney's Street Dawah preaching group in 2013, led by Mohammad Ali Baryalei, who later became a high-ranking Islamic State recruiter.
Another member of the movement helped him fly from Sydney to Turkey via South Korea and be escorted over the border.
Mr Zakhariev was reportedly staying in a house controlled by Jaish al-Muhajireen wal-Ansar, which his lawyer said was not a prescribed terror group at the time.
He only lasted eight days and left after observing the jihadists' brutality, then continued to travel across Europe before returning home to attend university, Mr Botev said.
In 2015 Mr Zakhariev reportedly attempted to travel to his father's home country of Bulgaria in but was questioned by ASIO at Sydney Airport. His passport was confiscated but returned two weeks later, according to Fairfax.
A year later he applied for a Bulgarian passport to travel to the country to help his elderly father Svetlomir, a former UN diplomat, who was moving back to his mother country. Svetlomir was trying to support his son when he died aged 82, two weeks ago.
Mr Zakhariev planned to work and travel across the European Union with the passport, his lawyer said. He also added that he visited a legal shooting range in the country's capital but it was not sinisterly motivated.
Sister Nevena Zakhariev said her brother had planned to study tourism in Canada or the US, but was soon arrested.
"At first, I just thought it was a big misunderstanding, we laughed it off thinking he'd be home in a couple of weeks because he's done nothing wrong," she told Fairfax.
"But as months and months passed, it became more serious. My fear is that the government wants to make an example out of him and he'll go to jail for something he didn't do."
A DFAT spokesman could only confirm "consular assistance" was being provided to an Australian detained in Bulgaria, in accordance with the Consular Services Charter, but could not confirm the person's identity.
Mr Zakhariev is due to face court on Friday.