A forensic pathologist has given evidence at an inquest suggesting an assault contributed to schoolboy Stephen Dudley's death, but an undiagnosed heart condition made him more vulnerable.
The final day of the coroner's inquest into Stephen's death is underway at the Auckland District Court, where three medical professionals are giving evidence.
The 15-year-old died following a fight after a school rugby practice in 2013. Two teenagers were charged with manslaughter following his death, but that was downgraded to assault after Stephen was found to have an undiagnosed heart condition known as sarcoidosis. The teens were later discharged without conviction.
Forensic pathologist Dr Paul Morrow performed an autopsy on Stephen's body following his death and found sarcoidosis in his heart -- a form of inflammation that can affect various parts of the body. However, the sample found was so small Dr Morrow needed a microscope to see it.
He could not find sarcoidosis in Stephen's other organs, and told the inquest it was relatively uncommon to just find the condition in the heart.
Dr Morrow said he believed the events leading up to Stephen's death, such as the assault, caused stress on his heart and his condition made him more vulnerable in that situation.
"It is highly likely that the stress of the assault induced a fatal arrhythmia in this young man," said Dr Morrow.
But a lawyer for one of the teenagers involved in the assault pressed Dr Morrow on whether the stress that he says caused Stephen's cardiac arrest could have built up from other factors in his life -- like studying for school exams.
Heart specialist Doctor Jon Skinner agreed the likely trigger for Stephen's cardiac arrest was the assault, but said he doesn't believe they'll ever know what the exact cause may have been.
"Nobody's certain in this room, all we know is that he collapsed and died during an altercation," said Dr Skinner.
Both doctors were questioned for almost five hours today, and it's that evidence regarding Stephen's heart condition which will be key to the Coroner's findings.
The inquest is expected to wrap up today.