The Mongrel Mob was born out of state-run institutions for teens in the 1960s - the very institutions under the spotlight for mistreating children in their care.
In recent years, the Royal Commission of Inquiry into Abuse in Care has probed these state and faith-based set-ups.
But there is a sense gang members have been reluctant to engage. That is something the Waikato chapter of the Mongrel Mob is out to change.
On Friday evening, Paul Zentveld, a former patient of the Child and Adolescent Unit at the notorious Lake Alice psychiatric hospital, spoke to a room full of Mongrel Mob members and their families.
He told them about his experiences there in the 1970s, when he was drugged and given painful electric shocks as punishment.
Zentveld's story began a weekend hui at Poihākena Marae in Raglan about trauma. It is run by the Waikato Mongrel Mob Kingdom, in what is thought to be a New Zealand first.
"It's all about, 'where did these people come from' - male and female," he said.
"They came from government institutions, and so they had no support, no help, and too, many have taken their own lives. Something's got to be done."
That could include getting gang members to share their stories with the Royal Commission and register for compensation and other redress, something Zentveld said was important.
"They have got a human right to be part of this whole abuse in care inquiry. No government's going to stop this. We're going to make a difference here. There's thousands of them, they told me the other day."
That is thousands of lives shaped by childhood abuse.
Waikato Mongrel Mob Kingdom public relations officer Louise Hutchinson said the hui included workshops on topics such as trauma and aggression, run by former gang member Lucky Te Koha and the Kingdom Brotherhood.
Waikato Mongrel Mob Kingdom public relations officer Louise Hutchinson. Photo / Andrew Warner
Some people might not be ready to look back on past trauma, but they should be given a chance to, or the skills to advocate for and support family members who needed it, she said.
"We just felt it was time to have the opportunity to run an event surrounding that. A lot of people still aren't really aware that the commission's on or what it's about, because they're just so busy living in survival mode."
Bringing Royal Commission staff into a setting comfortable for gang members could help break down barriers.
"They need to have their voices heard, and I think in the climate of crime and violence in the nation, and everyone saying, pretty much, 'It's all the gangs' fault' - well, the gangs have their own story to tell.
"I think that needs to become, just like the Land Wars and Polynesian Panthers, part of the education system. We need to tell the story of where this all started."
University of Canterbury senior lecturer and author of 'Patched: The History of Gangs in New Zealand', Dr Jarrod Gilbert, said the Mongrel Mob grew out of boys' institutions such as Epuni in Lower Hutt, and Kohitere Boy's Training Centre in Levin.
"It's directly where they formed, so the history between problems in state care and the Mongrel Mob is intrinsically intertwined."
While some gangs or chapters grew more anti-social and criminal, others were moving in the opposite direction.
Often this came with the age of members and their priorities in life changing, but the mechanisms were complicated.
"The Mongrel Mob Waikato, particularly in a Mongrel Mob sense, is in many ways breaking new ground.
"They're acting in ways we really haven't seen the Mongrel Mob behave. This hui is an example of that."
Gilbert said it could be hard to get gang members to trust the Royal Commission, even though it was independent of the government.
"There are cultural norms that have been created within the gangs, and that's a fierce sense of self-sufficiency and, really, a rejection of state agencies around them. That's been a core ethos of the gangs since they started."
The commission was sending three representatives to the hui. Its head of Te Tiriti engagement, Julia Whaipooti, said their main role was to listen.
"We know that there is a pathway and a connection between abuse that occurred in state care and those that look for community within a gang set-up, so it's really important for the inquiry that we are talking with, and accessible to, all survivors to share their experiences."
The Mongrel Mob Waikato Kingdom said the weekend's hui would not be its last dealing with trauma and abuse in care.
