The family of a West Auckland teenager who died after being attacked on a rugby pitch will seek manslaughter charges against his schoolmates, based on a new coroner's report.
Stephen Dudley died in June 2013, after a pair of brothers he went to school with punched him after rugby training.
A coroner's report found Stephen had an underlying heart problem and died when the stress of the assault induced a heart attack.
The 15-year-old had just finished rugby training when a teammate picked a fight. The teammate's older brother then joined in, laying one hard punch to Stephen's throat and more to his body.
Stephen collapsed on the field and despite CPR attempts by emergency services, he died in hospital less than two hours later.
The two brothers were charged with manslaughter but the charges were downgraded to assault after there was not enough evidence to connect the assault to the heart attack.
The boys were then discharged without conviction and with permanent name suppression.
However, coroner Gordon Matenga has accepted crown pathologist Paul Morrow's evidence that the assault was the most significant factor leading to the heart attack.
The Dudley family said the coroner's findings were vindicating but bittersweet.
The family felt robbed by their son's premature death and wanted justice, their spokesperson Ruth Money said.
The discharge without conviction was a dirty deal done between the lawyers, she said.
"We believe the appropriate charge is manslaughter, certainly against the eldest brother, who was very large when you compare the size of him and Stephen."
"It was a very violent, very physical assault... that's been backed up by the coroner's findings."
The family's lawyer, Nikki Pender, said they were writing to the solicitor-general to seek manslaughter charges against the two brothers.
"Stephen was happy and healthy one minute, the physical assualt happens, and he collapses."
There was no risk of double jeopardy - where someone cannot be tried for the same offence more than once - because the brothers were previously charged with assault, not manslaughter, Ms Pender said.
But the lawyer for one of the brothers, Ron Mansfield, said there was too much uncertainty over what was the key factor in Stephen's death and a new trial was unlikely.
"We're dealing with a criminal standard when looking at the culpability of a crime - the coroner's not."
"He's looking for the cause of death... They are quite distinct."
Assessing criminal conduct had already been done by people at a very senior level, involving specialists, Mr Mansfield said.
"The outcome was just and fair."
It was wrong to see the brothers as villains, he said.
The coroner recommended the school in question develop a CPR training program and said the Ministry of Education should form guidelines on the use of defibrillators.