A Sydney father who took his anger and frustration out on his infant son, fatally shaking the 10-week-old, has been jailed for at least three years.
The 26-year-old shook the baby with "probably an eight" out-of-10 force while trying to feed the boy in their Bidwill home in December 2019.
He called his mother, who said she became "hysterical" when she heard her grandchild couldn't breathe and urged the offender call an ambulance.
The baby's heart stopped before paramedics arrived.
While the boy was resuscitated, his significant injuries and "brain dead" state led to his death in hospital the following day.
The father initially denied he knew what had happened, claiming he'd walked back into the lounge room and found the child unable to breathe.
But he came clean days later, admitting he'd been "angry and frustrated".
He pleaded guilty to manslaughter while in the local court.
"I wasn't coping, to begin with, with what was going on in my life," he told police in December 2019.
The offender had laid his grandfather to rest a week earlier, lost his job a month before that and was dealing with his mother's cancer diagnosis, the Sydney District Court was told.
His relationship with the boy's mother, who'd been at work at the time, had become strained.
She was caring for her terminally ill mother and had her ex-boyfriend staying at the Bidwill home.
Judge Penelope Hock said the stressors could be described as "a perfect storm" before a tragic loss of control.
"The offence was spontaneous, arising from a sudden loss of control, brought about by a constellation of events," she said.
While not mitigating the crime, the father's recent drug use, including marijuana after the day of his grandfather's funeral and a relapse into methamphetamine use, partly explained the crime, the judge said.
The baby's death had been a devastating tragedy for his mother and the rest of the family, a factor acknowledged in the father's "profound grief and remorse" in a sentencing hearing last week.
His full and frank admissions were tangible evidence of his genuineness and insight into his offending, the judge said.
Judge Hock also commended the mother's insight after "while understandably devastated", she said she felt the father had not intentionally set out to hurt their infant son.
The judge found the offender's chance of reoffending was "highly unlikely" and his rehabilitation prospects reasonable, given his genuine remorse, employment history and support in the community.
The man's time in custody included weeks at a time in a cell for 23 hours a day because of other inmates' threatened and actual violence, the court was told.
His lawyer had also complained the father had been unable to access adequate treatment while on remand, resulting in a deterioration in his mental state.
Judge Hock set a head sentence of five years and three months in prison, dating back to the father's December 2019 arrest.
His three-year non-parole period expires in December 2022.