Police have established links between three men - one who was fatally shot, a second who was shot in the leg and another who has disappeared in suspicious circumstances.
Saso Ristevski, 37, was confronted by three men inside his home at Barina Avenue, Lake Heights, on September 28 last year before he was shot dead.
Officers found a substantial sum of cash at the scene and continue to examine DNA evidence.
Five weeks later, on October 31, 35-year-old Goran Nikolovski was reported missing by his family after leaving his Unanderra home in a Honda sedan.
Police found Mr Nikolovski's burnt-out car on a road off Macquarie Pass the following day. They believe he has met with foul play.
Investigations have since revealed the two men were known to each other and the two teams of detectives on the cases have been merged under Strike Force Calligan, police said on Friday.
They are also investigating the shooting of another man who was known to both men on January 29.
A 32-year-old man remains in hospital after he was shot in the leg outside his home in Barnes Street, Berkeley.
Two men are before the courts on charges relating to the incident, although investigations are ongoing.
Police want to speak to anyone with information about any of the incidents or the links between the three men.
They are asking a number of people who have anonymously contacted police previously to get in touch with them again.
