"This was a serious injury and it's important the proper message gets out ... that they can potentially die from the use of an air rifle."
The inquest heard after returning from school, Keegan said he was going to a farm shed to use an air rifle his father had bought him about six months previously.
A short time later his grandmother Patricia Pirini heard the shed door slam and saw Keegan lying on the ground "wriggling around like he was in pain".
Keegan said to his grandmother "I have been shot", before family members called the police.
Keegan was flown to Tauranga Hospital then taken by ambulance to Waikato Hospital where he died in the early hours of November 6.
An autopsy found he had been shot through the heart with a .177 calibre air rifle. The pellet had entered his chest between his ribs, travelled though his heart and was found lodged in his spine.
Detective Senior Sergeant Greg Turner of Tauranga CIB told the inquest the rifle's trigger could have caught on a foreign object and gone off.
"Perhaps Keegan was pulling the gun across the pool table toward him and it's caught on a foreign object, or any number of objects in the shed that it could have caught on. My best bet is it was accidentally triggered by being caught on a foreign object."
When asked by Mr Matenga if he had any message for the public about the use of air rifles, Mr Turner said they should be treated like any other firearm, locked away when not in use, and anyone under 16 should always be supervised.
Keegan's maternal grandfather Duncan MacPherson questioned whether Keegan should have been allowed to use the air rifle without adult supervision and why his father, Jayson Pirini, was not charged with any offence regarding the shooting.
According to New Zealand law anyone under the age of 16 is not allowed to use an air rifle without supervision.
Mr Turner said police did consider pressing charges against Jayson Pirini but after much discussion did not, instead issuing him with a pre-charge warning.
"It was my decision not to charge him. Clearly I'd seen the distress caused to Jayson by this incident. I considered the lesson had been learned."
Mr Turner said the air rifle was stored in Jayson Pirini's wardrobe and Keegan was allowed to shoot at targets without adult supervision.
In his statement, Keegan's paternal grandfather Francis Pirini said he and his son Jayson had taught Keegan about firearm safety.
