The 42-year-old handed himself into police after a 31-year-old Craigieburn man was killed in Taylors Hill on Sunday night.
The Caroline Springs man was interviewed but released without charge on Tuesday evening, with police to make further inquiries.
Emergency services were called to Vaucluse Boulevard about 11.30pm on Sunday, finding the Craigieburn man in a black BMW sedan with critical injuries. He died at the scene.
Police say the BMW had been following a white Mitsubishi sedan through the Taylors Hill estate when the Mitsubishi crashed into bollards.
It's believed a man got out of the Mitsubishi and confronted the male driver and male passenger in the BMW, before firing a shot into the car, killing the passenger.
No one else was physically injured during the incident.
The 42-year-old Caroline Springs man, believed to be the shooter, handed himself to police on Tuesday morning.
Detectives are confident they know the identities of the other two men.
Police believe it was not a random attack and the men are all known to each other.
Any witnesses or anyone who may have footage of the incident should contact detectives.
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