The father of a three-year-old Sydney boy who died after being left alone in a hot car has been released from police custody.
The boy was unable to be revived after being found in the car on Railway Parade in Glenfield in the city's southwest on Thursday afternoon.
Police were told the child had been in the car throughout the day.
The vehicle's owner, the child's father, broke the car's window to retrieve the boy before sitting nearby wailing and banging his head, the ABC reported.
The 45-year-old man was later taken to Campbelltown Police Station to be interviewed.
On Friday, police told AAP the man had been released from custody while officers continued investigating the death.
Campbelltown, near Glenfield, hit a top temperature of 33.4C at 4.30pm Thursday, according to Bureau of Meteorology data.
