NSW father in court over son's death

A Sydney father accused of stabbing his five-year-old son to death seemed confused and asked where he was during his first court appearance over the "horrendous" alleged murder.

The 36-year-old, who cannot be named for legal reasons, appeared via video link from Amber Laurel Correctional Centre a day after his son died in hospital.

"Where am I?," he asked after he sat down.

"You're at Parramatta Local Court on Saturday morning," magistrate Michael Price said.

The man had been questioned by detectives for most of Friday after allegedly stabbing his young son at Carlingford in Sydney's northwest between 6.30am and 7.15am.

The boy's grandmother tried to get him help by cradling him into a car and driving away.

She drove about 250 metres before she stopped to call for help, realising the extent of the his injuries.

The five-year-old died about an hour after arriving at Westmead Children's Hospital.

"The level of violence is horrendous ... it's probably about as bad as it gets," Superintendent Rob Critchlow told reporters on Friday.

The father during his court mention did not apply for bail and it was formally refused.

The magistrate made an order that he not contact prosecution witnesses, including family members, except where it is done by his lawyer.

The man didn't respond when his matter had finished and he was told he could leave the AVL room, with prison officers called to come and collect him.

He is next scheduled to face Parramatta Local Court on July 30.