But he later turned the chapter towards honest work. In 2005, he started a labour hire business called Rent A Bro to do painting, demolition and other work. The same year, Dunn co-founded Te Ara Tika o te Whanau Trust.
"We are setting this up for our kids, creating the employment, bringing them in," he told the Herald at the time.
The trust teamed up with the Salvation Army to organise a series of live-in P treatment programmes for gang members. One such reintegration programme was run from the historic Massey Homestead -- where Dunn's funeral will be held tomorrow.
The programme was given a $1 million grant over two and a half years from Prime Minister John Key's action plan on methamphetamine, launched in 2009.
The Salvation Army expressed its sorrow at Dunn's loss yesterday.
"It is with great sorrow that we pay tribute to Roy Dunn, a visionary like Moses intent on leading his people into the Promised Land. For Roy, that Promised Land was a better life for gang members and their whanau -- a life free from addiction and prison," the church said on Facebook.
"Our prayers are with Roy's wife Kerry and whanau at this time."
A convicted rapist, Dunn came from a troubled background. He was taken from his parents by the state at age 7 for stealing a bike from school.
Denis O'Reilly, a veteran community worker who employed Dunn as a youth worker, told the Herald in 2010 that Dunn did not see his family for another five years.
"So by the time he was 12 he was an angry, rebellious young fellow who determined to make war on New Zealand society."
Dunn said in a 2010 interview with the Herald he joined the Mob in the mid-1970s when he was 14. He changed course in the late 1990s after being introduced to Otara community worker Sam Chapman.
"We were already doing it 13 years ago - trying to make things better, without the drugs, without the criminal activities, to break the cycle for the next generation."
Dunn used his chapter's 25th anniversary celebration, attended by about 350 people in Onehunga in 2005, to launch a campaign to "eradicate" P in the gang.
He said the 130-strong Notorious chapter has lost 12 people to P in the past six years to 2010, mostly through heart attacks. "That was more or less a wake-up call. They were leaving behind their kids and grandchildren, and a lot of them got taken by CYFs."
Dunn also worked to bring young members of the Mongrel Mob, Black Power and Tribesmen together in an effort to end traditional gang rivalries.
Dunn was one of the two Mongrel Mobsters that Teina Pora falsely named during five days of confessions with police.
Pora apologised 20 years later in person to Dunn when he was released from jail on parole. Pora's conviction was later quashed by the Privy Council.
