“It’s an unprecedented reward for a crime of this nature, but we don’t want somebody who has killed, as they have on this occasion, out there in the community, we want them behind bars.”
Ms Roberts said police were also open to negotiating an immunity deal with anyone who came forward with vital information, including those who “had some involvement” or were “complicit”.
WA Police Assistant Commissioner Brad Royce said protection could also be offered if needed, conceding it could mean it could be required for “a very long time”.
“We normally do a lot more work before we get to this space but this is in recognition of having a gunman in our community who is happy to murder in front of … the community,” he said.
“WA Police have a long history of solving investigations, particularly homicides … and we don’t give up.”
Mr Royce said while the killer may have thought they had gotten away with the crime, the reward made it “highly likely [their associates] will talk”.
Mr Martin, 51, was fatally shot by a sniper while watching the Outlaw Nitro Challenge at the Kwinana racing venue with his wife and stepdaughter.
His stepdaughter’s partner, Ricky Chapman, who was sitting behind Mr Martin, was also struck in the arm by the bullet.
Surgeons have retrieved the bullet from the 31-year-old’s arm for police to determine the firearm used in the killing.
More than 100 police officers have been assigned to Operation Ravello, set up to solve the bikie killing.
Several bikie headquarters have been raided by police, and another six search warrants carried out on Tuesday.
Heather McNeill is a senior journalist at WAtoday.