Tony Di Falco, 61, was stabbed to death by Mehmet Bertan inside his Hillside home in Melbourne's northwest on October 4, 2024.
His brother Nick on Thursday detailed in the Victorian Supreme Court the void his death continues to leave on their grieving family.
"He was far more than a victim," Nick Di Falco said.
"He was a beloved brother, devoted father, a church member ... and heart of our family gatherings."
He said Mr Di Falco deserved peace and joy after having "fought and survived cancer and was looking to rebuild his life".
"What makes this tragedy more painful was his final moments (were spent feeling) fear and confusion," Nick Di Falco said.
"He suffered at the hands of someone he should've been able to trust."
Bertan, 34, has maintained his guilty plea to manslaughter after opting not to pursue a mental impairment defence.
He has been diagnosed with schizophrenia.
Six weeks before killing Mr Di Falco, Bertan experienced a psychotic episode where he falsely believed his family home would be robbed, prosecutor Cara Foot said.
He went to a service station, doused himself in petrol and planned to set himself alight to "distract" the supposed thieves from entering the home.
Psychiatrist Rajan Darjee previously told the court he did not believe the accused recovered from that episode and remained psychotic and unwell throughout the period.
Another psychiatrist agreed he was experiencing psychosis, though the experts were split on his awareness of that at the relevant time.
On the morning of the attack, after his mother and sister's partner had left for work, Bertan arrived in a taxi with a knife in a bag.
He walked inside before stabbing his stepfather multiple times, including three fatal blows to his neck.
Mr Di Falco collapsed and died out front trying to get help.
Bertan then broke into his sister's room, telling her, "one last sexual favour before I kill you".
He took all his clothes off, jumped into his pregnant sister's bed and grabbed her.
Once police arrived and distracted Bertan, she jumped out of the ground-level window.
Bertan was shot three times outside the home by retreating police.
The sister had previously moved out of the family home after Bertan threatened to sacrifice her and her unborn baby, the court was told.
She returned after he moved to a boarding home.
The offending arose from a decade-long serious mental illness which was not properly treated, leading to Bertan's self-control being "seriously impaired", defence lawyer Glenn Casement said.
Ms Foot said Mr Di Falco's death was a serious example of manslaughter and the judge needed to consider the community's protection.
Bertan's mother married Mr Di Falco in 2023 after his father's death in 2010.
Both parties agreed Bertan loved his stepfather and his stepfather loved him back.
He will be sentenced at a later date.
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