A jury has been told a man accused of drugging and killing a toddler in the New South Wales Hunter Valley almost 20 years ago had the opportunity to put antidepressants in his chocolate milk.
Cecil Patrick Kennedy has been on trial for manslaughter for three weeks in Sydney Downing Centre District Court.
He has pleaded not guilty to the unlawful killing of Jordan Thompson, aged 21 months, in Singleton on March 19, 2005.
Mr Kennedy is accused of giving the boy a toxic dose of antidepressant medication amitriptyline, known by the brand name Endep.
Drug allegedly in milk drink
In her closing address on Thursday, crown prosecutor Kate Nightingale alleged the drug was mixed into the infant's chocolate milk on the morning of the day he died.
"The accused prepared chocolate milk, there was a can of Nesquik in the accused's kitchen, so the accused had the opportunity to give Jordan Endep in his drink," she said.
The infant's mother, Bernice Swales, was in a relationship with Mr Kennedy at the time and the child was in his care while she was out.
Mr Kennedy first told police the boy fell out of the bath and later said he may have drowned when he left him for 40 seconds unattended, before returning and finding him face-down in the water.
The court heard when Ms Swales returned, the infant was "floppy and pale", with no signs of life.
Cecil Patrick Kennedy has pleaded not guilty to manslaughter. (AAP: Bianca De Marchi)
In her closing address on Friday, defence barrister Linda McSpedden said her client was an innocent man.
"The accused has stated repeatedly he did not administer any drug to the child," Ms McSpedden said.
"Nobody saw him administer it to him ... and if he had administered that drug ... would he not have immediately got rid of those tablets then?"
The jurors were told the tablets were seized from a cupboard in Mr Kennedy's unit three weeks after the toddler died.
Drug like poison
Ms Nightingale said Ms Swales was reluctant to give her children pain relief and likened antidepressant drugs to poison.
The jury was played a recording from a police device planted in Mr Kennedy's unit, in which she discussed her concerns about the drug being found in Jordan's system.
"It is killing me inside, who would have done it? I didn't even know they [the tablets] were there," Ms Swales said to Mr Kennedy in the recording.
"I never seen the box, I never touched the box, that's why I said to them [the police], 'What's he had in his system, poison you might say'.
"To think, like, that has happened, like knowing that he's f****ng, like, poisoned."
Cecil Patrick Kennedy has been standing trial in the Sydney's Downing Centre District Court. (ABC South East NSW: Adriane Reardon)
Ms McSpedden said Ms Swales had been angry with Mr Kennedy for cheating on her with another woman.
"He did not for one moment show the demeanour of someone who was lying [when speaking to police] ... in fact he was volunteering things all the time," she said.
"You might conclude that this accused was not the sharpest knife in the drawer ... he was brought down by his own stupidity and folly when [he] lied [about the affair]."
Judge Craig Smith has spent Friday summing up, before the jury is expected to retire on Monday.