Two innocent young men were executed by mistake in 2017 after Comanchero bikies shot the wrong people, Victorian police allege.
Police are urging those who know what happened to come forward in relation to the slayings in Melbourne of Muhamed Yucel in May 2017, and Zabi Ezedyar in August that year.
Detective Inspector Tim Day said the two men lost their lives "due to the callous stupidity, cavalier attitude to violence, and utter incompetence of members of the Comanchero Outlaw Motorcycle Gang".
He added police are "very, very close" to solving the murders.
Det Insp Day alleged that police have identified a number of Comancheros who had both direct and indirect involvement with the shootings.
"The actions of one individual in particular has brought scrutiny upon the club, and we know that there is angst amongst members of the club because of this," he said on Monday.
"Associates of one of the two suspects, who we believe is cowering offshore, have been both willingly and unwillingly involved in this offending."
Mr Yucel, 22, was leaving a garage via a laneway behind a house in Keysborough when several shots were fired, killing him and wounding two other men.
Investigators believe all three victims were shot as a result of incompetent gunmen attending the wrong property.
Three months later, 26-year-old Mr Ezedyar was shot visiting family friends in Narre Warren.
Mr Ezedyar was being greeted at the front door when he was fatally shot.
On this occasion detectives believe the gunman went to the right address but shot the wrong person.
Det Insp Day said officers know there are people sitting on the fence about coming forward, and urged them to do so.
"You know the line has been crossed on these two murders," he said.
"Again, these were two innocent young men who were doing nothing wrong and had their whole lives ahead of them.
"They didn't deserve to be gunned down by cowardly, incompetent fools."