Darko Janceski was killed in an execution-style murder outside his parents' home in Berkeley when a gunman on a motorbike fired several shots at him on April 14.

One bullet struck the 32-year-old in the heart, and he died on the way to hospital.

Police raided two homes on Tuesday morning in the nearby suburbs of Blackbutt and Cordeaux Heights and arrested two men, aged 24 and 38, who are being questioned by detectives about Mr Janceski's death. No charges have been laid.

Just months before his death, Mr Janceski's house had been firebombed and, in a separate incident, he was shot in the thigh outside his burnt-out home. He survived that shooting, only to be killed a short time later.

Mr Janceski was believed to be a disenfranchised member of the Comancheros outlaw motorcycle gang and had left the group on bad terms the year before his death.

In the weeks after he was shot in the thigh, Mr Janceski had expressed concerns to family and friends that he was "going to get whacked".

Detectives established Strike Force Calligan to examine Mr Janceski's murder, as well as the execution-style murder of Saso Ristevski, 37, in Lake Heights in September 2011.

Ristevski, who previously had been jailed for trafficking half a kilogram of cocaine, was gunned down outside his parents' house during an argument with three unknown men.

Five weeks later, Unanderra man Goran Nikolovski vanished and his burnt-out car was found in bushland at the nearby Macquarie Pass. Nikolovski had served time with Ristevski over the cocaine bust.

Police said the three men were all known to each other and shared a number of associates, and strike force detectives believe the cases may be linked.

A police spokesperson today said investigations into the death of Mr Ristevski and the disappearance of Mr Nikolovski were continuing.