Murder accused tried to help boy

A Sydney man accused of murdering a seven-year-old boy says he repeatedly asked the child's mother to call an ambulance but she told him he was overreacting, a court has heard.

The boy was found dead at his Oatley home in Sydney's south in May 2013 after relatives called paramedics, saying he had hurt his head falling from a pogo stick.

Following his death, the man was charged with his murder and a further 27 offences, including producing child abuse material, neglect and numerous counts of assault.

The boy's mother is also accused of murder.

Applying for bail on Monday, the man's lawyer told the Supreme Court the murder case against him was weak.

She said the man had told police in an interview in November 2013 that he had urged the mother "several times" to call an ambulance but effectively left the decision to her.

"He had only known the mother for some three months," his lawyer said.

"The accused says the mother told him `You are overreacting, he is going to be fine'."

She said the man had noticed swelling on the boy's head and had tried to care for him by using packets of frozen vegetables as ice packs.

The man's mother told the court she would post $5000 as security upon his release.

Meanwhile, a woman now dating the man's father said he was a "really nice guy" who was "very genuine" and she would be happy for him to live with her.

"He is a lovely guy who was just in a bad spot at the time," she said.

But the crown opposed his release, saying evidence suggested the injury wasn't from a "simple fall" but due to "violent force".

There were also concerns that if released he could pose a risk to his other children.

Justice Lucy McCallum will hand down her decision on Wednesday.