When the defence opened its case on Monday the jury was told Matiu's injuries were caused by a hyperactive child who catapulted into a small brick wall after accidentally tripping on a towel.
Yesterday Dr Garavan testified to the possibility of this scenario; concluding in a report that it was not an unreasonable possibility. That scenario included specific factors, including the boy having wet feet, running when he came into contact with a lino surface, and sustaining a subdural haematoma from a combination of hitting the brick wall and proceeding to fall down two steps.
Upon cross-examination yesterday crown prosecutor Steve Manning put to Dr Garavan that he did not consider that Huata had slapped the boy, an admission he made to police, in his report.
"I did not think much of it," Dr Garavan said.
Prosecution earlier called its own expert witness, neuropathologist Professor Colin Smith.
Mr Manning referred to Professor Smith's statement that if the defence's theory was correct it would be the first of its kind; with current medical literature holding no idea of such a fatal brain injury being caused in a home without circumstances such as falling out of a tree.
Professor Smith had previously said a scenario in which Matiu had accidentally fallen into a wall was "highly unlikely", to which Dr Garavan yesterday highlighted that being highly unlikely does not mean it's not possible.
When opening its case at the start of last week the prosecution said Matiu's injuries were more akin to those of someone involved in a serious car crash.
The jury is expected to hear closing arguments today.
