Ōpōtiki Mongrel Mob Barbarians boss Steven Taiatini died after he was run down by a ute in Ōpōtiki, police believe.
Hundreds of gang members attended the 45-year-old's burial at Hillcrest cemetery near Whakatāne on Wednesday.
A burnt out Holden Colorado 4-by-4 was found on Waitohe Valley Road, off State Highway 2, on Sunday morning and police believe it was set alight overnight on Saturday.
Detective Inspector Lew Warner said investigators suspected that vehicle was involved in Taiatini's death.
His fatal injuries were consistent with being hit by a vehicle, Warner said.
Police said they knew that several people saw what occurred on the night Taiatini died, and urged them to come forward.
Eight gang-related vehicles were searched on Wednesday night and police said they seized three firearms and six offensive weapons from five of the vehicles.
Two people were charged with firearms offences and two summonsed to appear in court for possession of offensive weapons and drug-related charges.
Police closed part of State Highway 2 on Wednesday as a convoy of hundreds of motorcycles and cars travelled from Ōpōtiki to the cemetery, while three schools were staying closed until Monday.
Bay of Plenty district commander Superintendent Tim Anderson defended the road closure saying if they did not exert some control it would be a "complete debacle".
"Whilst the roads were closed for a short period of time yesterday, if we had no involvement and it [was] left up to the gangs I can guarantee that those roads would have been closed a lot longer, due to the unlawful activity that they would have committed, due to a number of other things," he told RNZ's Morning Report.