Jock Palfreeman's father says it would be magical to have his son home for Christmas but he's worried the "corrupt process" that jailed him in Bulgaria may mean he will never return to Australia.
The 32-year-old - who spent more than 11 years in a Bulgarian jail after being convicted of murder - was released on parole earlier this week but is banned from travelling.
The prosecutor-general has also asked Bulgaria's highest court to re-examine the case.
Simon Palfreeman says despite his son tasting freedom for the first time in a decade he's worried Jock may be sent back to jail to serve the rest of his sentence.
"It's incredibly worrying that Jock could get so close within the legal system of Bulgaria to the point where we're actually looking at how to get him home, and then to be stopped at the last minute by the same corrupt process that saw him jailed for 20 years in the first place," the Newcastle-based pathologist told AAP on Thursday.
"I've got to the stage now where until he's back on Australian soil, I really do not trust that he will be let out of Bulgaria."
Nevertheless, Mr Palfreeman is desperately hoping his son could be back in NSW by Christmas to be reunited with his ailing grandparents.
"Having him home for Christmas would be a great thing for him, but also a magical moment for his extended family," he said.
"I just hope the Bulgarian system is strong enough to withstand this corrupt assault."
Palfreeman's parole angered nationalist politicians in Bulgaria prompting the chief prosecutor to ask for the review. The Supreme Court of Cassation has two months to make a decision.
He was convicted after fatally stabbing a local student in 2007, but shas always maintained his innocence, saying he was defending a Roma being attacked by football hooligans.
Palfreeman's Bulgarian lawyer, Kalin Angelov, says it would be a "huge catastrophe" if he's returned to jail.
"I don't know what will happen," the lawyer told AAP.
"We're in some very strange legal territory and nothing is following the rules."
Foreign Minister Marise Payne on Thursday said the Australian government was concerned "if non-legal issues were seen to have an influence on the process".
"We have called and continued to call for the Bulgarian authorities to allow Mr Palfreeman to travel to Australia given his paroled status," Senator Payne told parliament.
Mr Palfreeman and his wife, Helen, have drawn strength from their son's character as demonstrated by his work setting up the Bulgarian Prisoners' Rehabilitation Association.
"It's amazing that after almost 12 years of imprisonment in such terrible circumstances he's managed to maintain passion, emotion, a sense of humour and an ability to achieve results," he told AAP.
Palfreeman has indicated he could ultimately settle in Bulgaria.
His father says he would be happy for Jock - who speaks fluent Bulgarian and is currently staying with close friends in Sofia - to live in the country if the prosecutor-general's application is thrown out and it's safe.
Bulgarian radio reporter Ekaterina Katratcheva says Jock Palfreeman is a polarising figure in her homeland.
Ms Katratcheva told AAP while he was almost forgotten after spending 11 years in prison the granting of parole put Palfreeman firmly back into the public spotlight.
"It was like an explosion, it became a very hot topic and a very divisive topic for our society," she said.
"Almost everyone in Bulgaria knows his name."
Australian Associated Press