Why an expert on security in Mexico has serious questions about what happened ... trends now
An expert has raised major questions about a key theory that has emerged about the brutal deaths of two Australian surfers and their American friend.
The remains of Callum, 33, and Jake Robinson, 30, as well as their friend Carter Rhoad, 30, were found dumped in a 45metre-deep well on a property in Mexico's on Saturday, each with a single gunshot wound to the head.
The Robinson brothers, originally from Perth, were in northern Mexico on a surfing trip when they failed to check in to an Airbnb near the city of Ensenada in the Baja California region on April 27.
The official story from the State Attorney General of Baja California is that the trio were purely victims of petty crime.
Police allege the perpetrators saw the travellers' vehicle and wanted to steal the tyres, with the victims murdered when they resisted.
However, there are still many unresolved questions.
Australian brothers Jake, 30, (right) and Callum Robinson, 32, (second from left) are pictured with their parents Debra and Martin
Jack Carter Rhoad, 30, was murdered with the two Australian brothers
There have been suggestions that Mexico's infamous cartels and organised crime gangs were responsible for the murders.
Organised crime researcher Dr Philip Johnson, a lecturer in the College of Business, Government and Law at Flinders University in Melbourne, told Daily Mail Australia there wasn't much evidence to support the theory.
'I don't think there's anything here to say this came down the chain of command from a drug cartel or some other sort of criminal organisation,' he said.
'I think it's really important to say cartels aren't organisations with clear memberships, there's no card-carrying cartel situation.
'Larger and wealthier, more powerful organisations work with subcontracts to a lot of different local gangs.
'So these guys could be relatively petty criminals, not in any particular way associated with a larger cartel.
'That doesn't mean they haven't done business for them.'
Dr Johnson explained the cartels' involvement in violence was due to the impunity with which they were allowed to operate by the state, police and military.
According to local media, blood was discovered at three abandoned tents where the brothers and their American friend were believed to be staying before they vanished. A truck, said to belong to either Jake or Callum, was also found burnt out at a nearby farm (pictured)
Australian brothers Callum, 33 (left) and Jake, 30, were last seen with their American friend on April 27
'Some cartels are quite well armed and have very experienced 'soldiers', so to speak, but what really allows them to do what they do is the fact that they can do it and get away with it and do it again and get away with it,' he said.
Dr Johnson said the fact another body was found in the well with the Australian brothers and their American friend - which had been dumped previously - was evidence of this impunity.
The area where the murders occurred is currently under the control of the vicious Sinaloa cartel.
Members of the Sinaloa cartel have claimed they handed over the travelling trio's killers to the authorities.
A representative from the organisation denied any wrongdoing and said the cartel had turned over the culprits to police after becoming afraid of 'unwanted attention'.
'They were low-level robbers acting alone. But we handed them over,' the Sinaloa member told the Daily Beast.
'We learned that the cops were looking for the gringos and also began looking for those who were responsible. We called the authorities to let them know where to find them.'
In response to these claims, Dr Johnson said it was possible a branch of the Sinaloa cartel knew something about the triple murder, or took action after learning about the crime.
'Larger organisations will be more
