The eight-week-old girl's father had a ready explanation as to why she had a bruised face when her mother returned home.
The mother had been collecting her older daughter from school, leaving the father at home with their new baby and toddler son.
"Your son just gave your daughter a black eye," the father is alleged to have announced as she walked through the door.
"He hit her in the face with a hairbrush."
The little girl – who had been born premature and weighed just 2.75kg – was dead before the sun rose on the following day.
Her father stands accused in the NSW Supreme Court of her murder.
He cannot be identified for legal reasons.
The court heard that an autopsy determined the baby died as a consequence of blunt force causing a spinocranial injury, and that in addition to bruising and abrasions on her face she had further injuries that were outwardly undetectable.
These included a skull fracture, retinal haemorrhages, spinal cord damage and rib fractures.
"All of her ribs at the front of her chest and back of her chest had been injured during her life," Crown prosecutor Margaret Cunneen said in her opening address to the jury.
"Some were injured, some were healing, and some were almost healed."
The baby's older sister, who was six at the time of her death, said in her police interview that the baby's father – who was her own stepfather – was "always hurting [the baby]", the court heard.
"He always throws [the baby] on the bed when she's crying," she is alleged to have told police.
"He's always shaking her up and down. He pushed his right hand right into her stomach. He put his one hand behind her back and one hand on her stomach and pushed [the baby] right hard."
The girl, now 9, will give evidence by video link to the court.
The accused man's barrister, Hugh White, said he had pleaded not guilty to murder and denied causing his daughter's death.
"A lot of what has been said, [the accused] disagrees with," Mr White said.
The court heard that later on the evening of the hairbrush incident, the baby's breathing became irregular, before finally stopping after 4am and an ambulance was called.
Kirsty Danvers, who was the first paramedic on the scene, said when she arrived at 4.58am she noticed bruising on both the baby's eyes and her forehead.
"I picked her up and started performing CPR in my arms while walking to the ambulance," Ms Danvers said.
"She was not breathing, she had no pulse, she was grey and she was limp."
She said as other ambulance officers arrived on the scene and noticed her bruising, they exchanged glances.
"We just looked at each other and said, 'What's with the marks there?' " paramedic Rory Shanahan told the court.
The trial continues.