Standing behind 33 white crosses, one for each police officer killed in the line of duty, Diane Hunt said her son was killed because of his uniform.
It was because of his badge that Matthew Hunt was shot and killed in Auckland on June 19 while doing a routine police traffic stop, she said.
"Each day I think, 'Why Matt?'
"But then I think to myself, 'Well who should it be then? I can't say it should be Fred or Ted. But why Matt?' There are no answers. I don't know," Hunt said.
"So, I just sit there thinking, 'Why Matt? Why Matt?'"
Hunt said she wanted to make change in her son's name which would improve the lives of police officers who keep New Zealanders safe "every single day".
Hunt today presented Parliament with a 39,286-strong petition calling for mandatory life sentences for people convicted of murdering a police officer and their parole eligibility automatically declined.
The petition says the move would require amendments to the Sentencing Act 2002 and the Parole Act 2002.
Hunt launched the petition on July 30 - the day her son would have turned 29.
"I want no parole for the killers of police officers in New Zealand - a murder sentence here can mean about 10 years in jail and I don't believe that's an appropriate sentence for the murder of a public servant doing their job," Hunt said.
"First responders have this on their shoulders every day they go to work, they all need to get home.
"I don't want to suggest arming the police, but there needs to be another deterrent and this could be the way to stop this happening to any other person in New Zealand."
Upon presenting the petition to Police Minister Poto Williams, Hunt urged elected members to use their place in Parliament to give life to the petition.
She was supported by her local MP for Whangaparoa, National's Mark Mitchell, and Matthew Hunt's friend Sam Swaffield who presented her with a taonga in honour of the 33 police officers who have been killed in the line of duty.
Williams committed to putting the petition through the full select committee process but said the change might be required by the judiciary and the levers it had during sentencing.
"And I support that. This is a matter that will ultimately sit with the courts and the justice system."
But that would be part of the select committee process of the petition.
Hunt was killed as he and his partner tried to pull over a car just before 10am on June 19.
He was shot multiple times with a long-barrelled gun, which the Herald understands was a high-powered assault rifle.
Hunt's colleague was also shot several times but managed to get away and survived the attack.
A man has been charged with murdering Hunt, attempting to murder the other police officer and wounding a member of the public as he allegedly fled the scene in a car.
A woman has been charged with being an accessory to Hunt's murder after the fact, by enabling the accused killer to leave the scene in a car and avoid arrest.
Both have pleaded not guilty and are in custody awaiting trial in the High Court at Auckland next year.