Officers descended on the quiet northern Sydney street where Mr McGurk was murdered four months ago and, using lasers to determine possible bullet trajectories, recreated four possible scenarios - that he was shot from just outside his car door, from across the street, or from two positions in garden beds further away.
By the end of the day police had all but ruled out the possibility of a long-distance shot.
"Following the scenarios we have enacted this evening, we believe that Michael McGurk was shot at close quarters," head of the murder investigation, Acting Superintendent Mick Sheehy, told reporters at the scene last night.
"What we have established this evening is that the likelihood of firing a shot greater than 10 metres, greater than the width of this street, you need someone with some specialised training and equipment capable of conducting that shot ... it's unviable."
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Supt Sheehy said Mr McGurk could have been shot as close as one metre away from his car door, but it was "certainly a viable option" that he had been shot from a car positioned across the road.
Detailed re-creation
Police parked a Mercedes-Benz identical to that driven by Mr McGurk at the exact point on Cranbrook Avenue, Cremorne where the 45-year-old was shot in front of his son, then aged 10.
If he had been shot from across the road, it was unlikely his assassin would have been able to see the boy sitting in the front seat, Supt Sheehy said.
A mannequin was placed in the driver's seat to represent the position police believe Mr McGurk was sitting in when a bullet struck him in the head on September 3 last year.
Supt Sheehy said the re-creation was as much about confirming suspicions as it was about eliminating possible options, although Thursday's investigation had reinforced and consolidated forensic evidence.
"There is a number of theories which we need to either establish or negate to being a viable option in relation to the murder of Michael McGurk," Supt Sheehy said.
Mortgage fraud
Police are yet to charge anyone over the killings after months of investigations by scores of detectives, although Supt Sheehy confirmed they were investigating a number of persons of interest.
Since his death, Mr McGurk has been linked to an alleged $150 million mortgage fraud racket involving hundreds of Sydney homes.
"To be honest there is a number of people who had some conflict with Mr McGurk," Supt Sheehy said.
"He had some questionable business practices which have been identified (and) there is significant lines of inquiry."
Unmarked police cars were brought to Cranbrook Ave and parked in the exact place other vehicles were parked on the night of the shooting.
Lengths of green cord were used to highlight the "sector" from which the bullet was fired.
Two men believed to have witnessed the shooting and seen in the area at the time are still wanted by police.
Forensic tests
There have been numerous forensic tests carried out on objects seized from the scene and police also say they have a number of firearms but have not confirmed if the offending weapon is among them.
"We have a number of weapons in our possession which we are examining," Supt Sheehy said.
"At this stage I'm not in a position to say we have or have not obtained the murder weapon."
Police would not say if Mr McGurk's wife and children are still living at the Cranbrook Ave address.
