The stepfather of a three-year-old boy who died after reportedly being knocked over by the family dogs has told 9NEWS: “I have nothing to hide.”

Joey Woodcock died in Westmead Hospital last week after being injured at a park near his home in Oberon.

His mother Lupe Naa and stepfather Andrew Woodcock told police the boy died after tripping over a lead while out with the family dogs.

A strike force of local detectives and members of the NSW homicide squad has been investigating the child’s death.

Today, Mr Andrew Woodcock, told 9NEWS it was a tragic accident.

"I have always said to the detectives I will tell you whatever you want to know. I have got nothing to hide.”

When asked if he understood why people were suspicious, he replied: “Yeah, a young kid died. Of course they are going to be suspicious.”

Mr Woodcock described how Joey was injured.

“They were just playing in the park. The dogs were on the rope. They pulled it out of my hand. It got him by the legs and flipped him backwards."

Joey was given CPR at the scene, first by his parents, then by paramedics. But he died in hospital days later.

"I checked Joey's pulse. There was a faint one....but his eyes were glazed over and stuff. But the detectives don't believe my story,” said Mr Woodcock.

Mr Woodcock admitted to 9NEWS he had hit the boy in the past.

"I said to the detectives I have smacked him when he has been naughty like a normal parent does."

Police issued a statement at the time saying: “Police were told the dogs were walking on a lead and they’ve got loose, tripping the child over with the lead."

They added: “We’re now trying to determine if the injury is consistent with what we have been told by the parents.”

Andrew Woodcock has admitted he hit his stepson in the past. (9NEWS) (9NEWS)

Andrew Woodcock spoke exclusively to 9NEWS about his stepson's death. (9NEWS) (9NEWS)