Connor Morris had rejoined the Head Hunters in recent months - a notorious gang which Sir Paul Holmes, Millie Elder-Holmes' father, condemned before becoming fond of his adopted daughter's partner.
Police believe the death of the 26-year-old was a random act of violence rather than a gang-connected hit.
Read more: Emotional visit to gang HQ for Millie
But the revelation that Mr Morris was back in the fold of the motorcycle club's East Chapter in Ellerslie after leaving the gang several years ago could increase the risk of retaliation on those responsible for his death.
"The guilty will be punished and held accountable for their gutless, weak actions and feel our flames," a senior member said on social media.
A recent photograph shows Mr Morris wearing a leather vest, or "cut", emblazoned with the chapter's distinctive skull insignia and standing in a gym beside other Head Hunters including William "Bird" Hines and professional fighters James Te Huna and Mark Hunt.
"I was privileged to meet two of the biggest names in the fight game last night," Mr Morris, who had trained as a fighter, wrote in June.
Underworld and police sources said Mr Morris was kicked out of the club after falling foul of its hierarchy, some time after he and girlfriend Miss Elder-Holmes made headlines for drugs charges in 2008.
The photograph of Mr Morris wearing a cut was the first sign police saw that he was back in the gang as opposed to simply being the son of senior member Chris Morris.
Other signs were that funeral notices are signed HHFFHH - Head Hunters Forever, Forever Head Hunters.
He and his father, Chris, also known as One Eye, both shifted from the West Chapter of the gang to the more "disciplined" East Chapter, which is run by president Wayne Doyle.
Members of the East Crew are banned from smoking methamphetamine.
"A lot of guys will transfer to East if they've had enough of that scene.
"If you're trying to kick a drug habit, that may be a motivation," said one source with knowledge of the gang world.
Broadcaster Sir Paul Holmes became a vocal campaigner against methamphetamine when his stepdaughter was in the midst in her addiction battle and was a strong critic of the Head Hunters and their "scum ilk".
He was estranged from Ms Elder-Holmes because "we will have nothing, ever, to do with Head Hunters".
But the young couple overcame their battles with P and Sir Paul later reconciled with his daughter and her partner.
"He really liked Connor and gave him a lot of credit for turning their lives around," said one family friend.
* This story has been removed from Facebook because of insensitive comments about the death of Connor Morris.
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