Manning said Huata was the only adult in the house during the time window in which the alleged injuries were sustained and urged the jury to consider the facts and evidence only.
The Crown told the jury the evidence showed Huata was a good stepfather until he snapped and lashed out, causing the death of Matiu.
However the defence said the boy had sustained the injuries by tripping over in what Huata's lawyer, Russell Fairbrother, described as a "freakish accident".
Fairbrother said "not one neighbour heard a sound of a child being tortured or attacked" and added that Huata had no history of violence or bad behaviour.
Manning said the jury would hear from experts that Matiu died of a significant head injury by way of blunt force trauma, akin to injuries that could have been caused by a car accident.
An aunty of the Flaxmere toddler, Jolene Morrell, described the young boy to the jury yesterday as happy and bubbly, but full-on.
The trial before Justice Susan Thomas is expected to last two weeks.