A man accused of killing his toddler stepson, who he shut in an esky filled with ice and restrained with duct tape, treated the boy like his own child, a court has heard.
The man and the boy's mother are jointly accused of murdering the three-year-old and concocting a story that he'd been tripped by a rope tied to the family's dogs in an Oberon park in August 2014.
In an interview taped more than a month after the boy's death, the man told police he taped a ball into the child's mouth and caused his penis to swell by flicking it with a wooden spoon.
"I treated him as my son ... everyone keeps twisting everything," he said in the interview played to the pair's Supreme Court trial on Wednesday.
"It was about being a family and ... like when we went to shopping the kids always come (sic) first."
The trial has previously heard the boy, known by the pseudonym Timothy, had only lived with the pair for about seven weeks before he was found in cardiac arrest at their home by paramedics.
The stepfather told police he wanted to be formally recognised as Timothy's carer and was angered when he was ignored by emergency staff treating the boy the month before he died.
He told police he put Timothy in the esky because he was trying to treat bruises on the back of his legs and once shut the lid because the boy kept trying to get out.
The child's hands were restrained on another occasion because he kept trying to take duct tape off his eyes, he said.
"Youse explain it like it's ... terrible or whatever but it was only a short period of time," he said about shutting the boy in the esky.
Timothy died in hospital three days after his mother called triple zero and said he wasn't breathing.
The stepfather said the boy always had injuries, including some he couldn't explain, and was once left at home amid concerns about how his appearance would be perceived during a visit to Sydney.
He told police not getting the boy help was "negligence and all that stuff".
"I understand it looks bad," he said in the interview.
"I should have just said 'stuff it, take him to a doctor'."
The Crown alleges Timothy's mother likely inflicted the fatal injury and that the stepfather was complicit because he must have known she wanted to and could kill him.
The defence has asked the jury to put their emotions aside, saying there was some medical evidence the boy's injuries were consistent with a fall.
The trial continues.