Zeljko "Steven" Mitrovic, 45, was shot dead at his Dynamic Transport business in Hassall Street, Wetherill Park, after a heated confrontation with up to seven men at 3.50pm on Tuesday.
Detectives said yesterday that, after an initial exchange in the company yard, Mitrovic was followed to his first-floor office by three men where a further altercation ensued, resulting in one man producing a gun and shots being fired.
A 31-year-old worker at the facility was shot in the right arm, although police believe he was not a target of the attack and has no links to any gang.
A senior police source confirmed the identity of at least one individual involved in the melee had been established and, once found, would be formally questioned.
Detectives are now creating a vast personal and financial profile of Mitrovic's life, including his many business and company interests, which are believed to be at the heart of the conflict.
They do not believe the murder was bikie-related.
Mitrovic and his wife, Suzana, were due to appear in the Sydney District Court today for a civil matter in which they are suing a man whose dog allegedly bit their son.
Legal sources yesterday said the matter was not related "in any way" to the shooting.
Mitrovic, jailed over a double-murder in 1998, was a member of a newly formed Hells Angels chapter at Burleigh Heads.