Two burnt-out cars were found in nearby Croydon Park and Bexley North a short time after the shooting, with police probing a connection.
On Tuesday night, Comancheros sergeant-at-arms Tarek Zahed and his brother Omar were sprayed with bullets as they left BodyFit gym in Auburn.
Omar died at the scene after going into cardiac arrest, while Tarek survived wearing 10 bullets to the head, torso and legs.
He remains in a stable condition in hospital after making it through surgery on Wednesday.
Security has been increased around Zahed’s hospital room, with police on Friday confirming a Comancheros associate was charged with stalking and intimidation after being refused entry twice, and allegedly threatening a security officer.
Police are still searching for Omar’s killer.
Two weeks before the Zaheds were attacked, fellow underworld figure Mahmoud ‘Brownie’ Ahmad was killed in a hail of bullets as he left a Greenacre home.
Nobody has been charged over Ahmad’s murder.
Police say they had warned both Ahmad and the Zarek brothers that they were marked men. Just days before he was killed, Ahmad was told there was a $1 million bounty on his head.