Edin Smajovic, 23, was shot once in the chest soon after arriving at a Campbelltown car yard with associate David Meatuai at about 2.30pm on January 9, 2009.
A recent statement by one of the original investigating officers, Detective Senior Constable Max Kral, has pointed the finger at Anthony Tan, one of two owners of the Macarthur Auto Centre, who was initially charged over the murder, along with his colleague Nathan Reddy.
"From evidence and information available to me at this time I believe that sufficient evidence exists which identifies that Tan is responsible for the murder of the deceased Edin Smajovic," Senior Detective Kral said in the May 2017 document.
A large brief of evidence was tendered before Deputy State Coroner Teresa O'Sullivan in the Glebe Coroner's Court during a short hearing on Monday.
Police dropped their case against Mr Tan and Mr Reddy in February 2013 - understood at the time to be partly due to a confession by a prosecution witness.
In her opening address, counsel assisting the coroner, barrister Peggy Dwyer, said Mr Reddy had given police conflicting versions of events during multiple interviews.
Tan has consistently refused to be interviewed.
Senior Detective Kral said he found a version put forth by Mr Meatuai in August 2009 to be the most believable.
He claimed that while they were speaking to Mr Reddy outside the workshop doors, Mr Tan walked into the workshop and retrieved a gun from a white car, cocking it.
Mr Smajovic then allegedly produced his own gun and held it to Mr Tan's head, telling him repeatedly to put the gun down.
"Mr Tan shook his head, turned his body to the left and shot Mr Smajovic, who shot back straight away," Ms Dwyer told the court.
Senior Detective Kral said he believed Mr Smajovic and Mr Meatuai had attended the workshop over a drug debt, and that Mr Tan and Mr Reddy had armed themselves following a previous confrontation.
He said he believed there was evidence that, after taking Mr Tan to hospital, Mr Reddy went to an unidentified location and disposed of the gun used to shoot Smajovic.
Mr Tan was under police guard while being treated in Liverpool Hospital for a gunshot wound to his shoulder.
According to events in Senior Detective Kral's statement, the two officers guarding Mr Tan were instructed to temporarily leave the scene by a superior, giving Mr Tan an opportunity to wash his hands.
Mr Tan discharged himself from hospital against medical advice and flew to Vietnam days later.
Senior Detective Kral said a PACE alert, which would notify police if Mr Tan attempted to leave the country, had been requested but not been put in place before Mr Tan left for Vietnam.
Senior Detective Kral said he believed there was information to suggest Mr Tan signed himself out of hospital "to prevent covert investigation techniques being used by police against him".
"I believe he fled Australia days later to prevent him from being targeted similarly in the ensuing investigation. I believe this displays evidence of flight and knowledge of guilt," he said.
"This stolen property included records made by Detective Sergeant Bristow of a conversation he had with an informant," Senior Detective Kral said.
He said he and Detective Sergeant Bristow interviewed a man in relation to the murder in July 2010, and that that man said he'd been told that Mr Reddy had possession of the stolen laptop, and it had "all the stuff with the case on it".
"The comment about the stolen property was made without any prompting," Senior Detective Kral said.
Ms Dwyer told the court there were a number of factors about the police investigation that were of serious concern, "and may indeed have impacted on your Honour’s ability to determine the manner of death".
Ms Dwyer said she didn't suggest Ms O'Sullivan suspend the inquest and refer it to the Department of Public Prosecutions, nor that she make a finding about who shot Smajovic.