Nikola Golem, 51, was sentenced to nine years in jail on Friday after he failed to attend to the needs of his stepfather Tomislav Nemes before his death in February 2022.
But he will be eligible for parole on August 21 after Supreme Court Justice Rebecca Treston took into account almost three years served in custody and Golem's serious physical ailments.
Mr Nemes' two grieving daughters from his first marriage described their anguish at being cut off from their father for months before he died and their desperate search for answers afterwards.
They described how Nemes had been brutally betrayed by Golem, who failed to seek medical attention for Mr Nemes after he fell into a coma and died in his Gold Coast home about February 24, 2022.
The court heard Mr Nemes shared the home with his stepson and second wife Dragica, who has refused to co-operate with police inquiries and has not been charged.
Mr Nemes had been bed-bound for six months before his death and the court was told he and his wife, who was a Jehovah's Witness, were suspicious of conventional medicine.
The court heard the successful businessman had his phone confiscated by Golem after he was suspected of making speculative financial investments, cutting him off from his family.
In her victim impact statement read to the court by prosecutor Stephanie Gallagher, Mr Nemes' daughter Suzanna Beljanski described how she and her children drove from Canberra to the Gold Coast in desperation in April 2023.
But she was denied entry and did not know her father had been dead for more than a year.
When police entered the property four days later to conduct a welfare check after pleas from his daughter, they were confronted with Mr Nemes' decomposing, unrecognisable and partially mummified remains.
Ms Beljanski told the court how Mr Nemes had been cut off from his family, children, grandchildren and elderly mother after earlier maintaining a close relationship with all of them.
"He lost his safety in his own home, he lost his dignity, he lost his children," she said in her statement.
"When he died, he was not given the basic respect for the dead."
The court heard that for a time Mr Nemes' wife had continued to sleep alongside him until the smell became overpowering after being lied to by her son, who told her his condition was improving.
Mr Nemes was sealed in the air-conditioned room with a towel under the door.
His other daughter, Elizabeth Marzano, told the court how their father had cared for his significantly disabled stepson.
"He carried Nik on his back up flights of stairs because he believed he could not manage them himself ... he drove him wherever he wanted to go so Nik would never feel isolated or left behind," she said.
Golem's lawyer agreed the objective facts of the case were horrific.
However, he pointed to mitigating factors, including his client's disabilities, cognitive impairment and the alleged failure of his second wife to take appropriate action before or after Mr Nemes's death.
"He didn't murder anyone," lawyer Martin Longhurst said.
Golem, who pleaded guilty to manslaughter and interfering with a corpse, had continued to provide care for Mr Nemes until he fell into a coma, the lawyer said.
But he admitted that his client's behaviour after Mr Nemes' death was "incredibly grotesque".
He told the court Golem suffered a brain injury in a car crash when he was eight months old, causing him to be intellectually impaired, with an estimated IQ of 70.
He said his time in custody had been spent in a wheelchair, he wore protective headgear after a chunk of his skull was removed and he suffered seizures.
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