Members of the Mongols bikie gang spent weeks spying on a defector and electronically tracking his BMW before executing him in a hail of bullets, Gold Coast police say.
Detectives have no doubt the gang is responsible for the hit on former member Shane Bowden, who was shot 21 times with a machine gun and a shotgun as he sat in his car outside his Pimpama home last October.
The 48-year-old, who'd defected to rival bikie gang the Finks, had months earlier escaped an attempt on his life in Melbourne and fled to Queensland.
Police still don't know the identity of the two shooters who carried out the execution, but hope security camera footage of two men fitting a tracker to the underside of Mr Bowden's black BMW might finally crack the case.
They have also released footage of a number of vehicles of interest, cutting laps around Mr Bowden's residential complex and surveilling his movements in the three weeks before he was murdered.
"We believe this crime has been committed by members of the outlaw motorcycle gang, the Mongols," Detective Superintendent Brendan Smith told reporters on Friday.
"This is the extent of their sophistication, that they are using tracking devices and personal surveillance on their victims."
Det Supt Smith said a recent search at a related crime scene at Fernvale had uncovered important evidence, including electronic devices and a vehicle of interest.
Just last week police also released vision of a blue or silver coloured Holden Commodore and a maroon coloured Ford Falcon they believe were used as getaway cars after the execution. They were later found torched.
"We know there was a number of people involved right through from the actual shooters, to the planners, to the leaders, to those involved in providing those getaway vehicles that were burnt out," Det Supt Smith said.
Investigators have offered protection from prosecution and a $250,000 reward to any accomplices to Bowden's shooting who could help solve the crime.
"This is their opportunity to come forward and seek this indemnity," Det Supt Smith said.
"Don't be the last one on the bus - it might be too late and you'll find yourself sitting in the dock."
Bowden was initially a member of the Finks and was part of its "terror team" jailed over the Gold Coast's so-called ballroom blitz brawl in which three people were shot and two stabbed in 2006.
After his release he defected to the Mongols but was booted out and rejoined the Finks just before he was killed.
