NSW toddler's murderer jailed for 35 years

A NSW man has been jailed for 35 years for the bloody murder of a 20-month-old toddler.

Timothy Andrew Whiteley, 28, was the only person near the girl when witnesses heard a large bang emanate from her room in a Newcastle home in June 2018.

He attempted CPR and tried to keep her alive, telling police he believed the girl had fallen out of bed and hit her head.

But, after a Newcastle jury in November convicted the 28-year-old of murder, NSW Supreme Court Justice Stephen Rothman said the substantial, fatal injuries inflicted could not have been accidental.

The toddler, weighing 11kg and standing 84cm tall, died from multiple injuries, including bleeding to the brain, broken ribs, a collapsed lung, lacerations to her liver and bleeding in her abdominal cavity.

Blood splatter in the room suggested Whiteley initially assaulted the girl in her bed and then may have thrown her forcefully into a chest of drawers, the judge said.

Whiteley's motive was suspected to relate to text messages between the toddler's mother and another person.

But the judge couldn't make a finding beyond reasonable doubt about the specifics or motive for the attack.

"I do not have an explanation for an assault of a young child of extraordinary violence," Justice Rothman said, in reasons published on Thursday.

The judge accepted the former Steggles chicken chaser had "snapped" in a spontaneous and unplanned outburst.

But Whiteley, who'd been stressed about the loss of glasses that held substantial sentimental value, had no history of domestic violence and there was no history of abuse against the toddler.

"Yet the offence occurred ... and a young, defenceless infant is dead," the judge said.

He acknowledged Whiteley suffered nightmares and other issues related to being a child abuse victim and a child witness to domestic violence.

Whiteley had good prospects of rehabilitation, notwithstanding untreated emotional dysfunction, the judge said.

With his sentence dated from his arrest in August 2018, Whiteley will be eligible for parole in 2042.

The toddler's mother was this week found guilty by another Newcastle jury of the girl's manslaughter due to the four-and-a-half-hour delay in calling an ambulance.

The woman testified at Whiteley's trial and denied attacking her daughter before she was put to bed about 11.30am.

She is due to be sentenced on April 23.