A feared standover man made a fatal mistake when he 'b***h-slapped' a powerful property developer while threatening him, according to underworld sources.

Hussein 'Skinny' Dehaini had reportedly attempted to extort the Middle East-born businessman before his gangland execution at Ascot Vale, north of Melbourne's CBD, in the early hours of Sunday morning. 

The ex-professional boxer, who retired in 2019, was blasted with bullets as he walked to his car. He tried to flee but the gunman chased him down and shot him again.

He had earlier attended an event at Trombar restaurant in Ascot Vale at 9pm on Saturday, and then partied on late into the night.

Dehaini left after midnight and had only walked a few metres towards his car before he was gunned down outside a vacant food truck.

The burly victim stumbled to a nearby Woolworths loading dock, where he was located by emergency services, but later died. 

'He's been out there for a meeting and thought he was okay,' an underworld source claimed. 

'Calls were made - and he was brown bread [dead].'

Controversial true crime reporter Ryan Naumenko said the attack was sparked by Dehaini slapping the powerful Melbourne property developer at an earlier meeting. 

'Dehaini allegedly physically b***h-slapped him around. Great offence was taken,' he wrote on his Outlaw Media website on Tuesday.  

Naumenko claimed the insulting act had been the trigger that sealed his fate.

'When the developer felt the pressure, another formidable interstate underworld player was reportedly brought in on his behalf to neutralise the threat,' he wrote. 

'The result was a professional hit in the early hours of Sunday morning in Ascot Vale.'

Another underworld source told Daily Mail Dehaini had been under the impression he was on safe ground that night. 

'But the (developer) already had boys here from Sydney ready to hit,' he said.

Dehaini had been well known to Victoria Police detectives after he was previously charged during an Echo Taskforce investigation into a Melbourne businessman who was allegedly bashed and kidnapped from his home.

One of the accused was a senior Melbourne outlaw bikie figure who was allegedly engaged to put the squeeze on the victim over an unpaid debt, the Herald Sun reported. 

Homicide Squad Detective Inspector Dean Thomas said on Monday that Dehaini’s links to both Middle Eastern organised crime groups and bikie gangs had complicated the investigation

'He does have criminal history and obviously he is associated with a number of serious organised crime groups,' he said.

'We take that into account and we have to consider that. Our mind is open to all previous crimes.'

Detectives have released footage of the killer’s getaway vehicle, which nearly mowed down a pedestrian seconds after the deadly ambush.

The white Mercedes C-Class was seen speeding and swerving through the intersection at Epsom and Racecourse roads, almost striking the man trying to cross the road.

That vehicle and its occupants remained at large on Tuesday.

Naumenko claimed Dehaini had been operating as an unofficial enforcer for Kazem 'Kaz' Hamad - the man accused of running Victoria's illicit tobacco trade. 

'That connection, combined with his long-standing links to Middle Eastern organised crime groups and outlaw bikie gangs, gave him serious weight,' Naumenko reported. 

'He had form as one of the early "soldiers" in Melbourne's tobacco wars that exploded in 2023, using his muscle to extract money from shop operators on behalf of syndicates.'

Naumenko claimed Dehaini had been respected among fellow criminals.  

'This particular beef was not some long-running vendetta. It erupted suddenly and escalated fast,' he added. 

'He was well connected in the worlds of Middle Eastern organised crime and outlaw bikie gangs. But even the most connected figures know there are lines you do not cross without consequence. 

'Slapping around the wrong developer, in the wrong circles, at the wrong time, was apparently one of them.'

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.