Callum Robinson, 33, and his brother Jake, 30, were on a surfing trip with their American friend Carter Rhoad, 30, in the state of Baja California when they failed to check in to a pre-arranged accommodation near the city of Ensenada.
When Mexican police arrived at their last known whereabouts, they discovered a campsite covered in blood.
Days later, three bodies were found in a well and earlier this week the brothers’ parents travelled to Mexico and confirmed their identities.
“It is with heavy hearts that we share the news that Callum and Jake Robinson have been murdered,” mother Debra Robinson told reporters after travelling from Mexico to San Diego, California.
“Our hearts are broken and the world has become a darker place for us.”
Baja California is well known for beautiful beaches and tiny villages and the trio’s last images on social media showed them enjoying these sites.
But the northern border state is also rife with violent crime, with the Australian government’s Smartraveller website warning of drug-related crime and gang violence.
Baja California state prosecutors believe the alleged killers were driving by when they spotted the trio’s pick-up truck.
They attempted to steal its tyres and parts but the men resisted.
All three were found with bullet wounds to the head.
The alleged murderers attempted to destroy the evidence, burning the tent and driving the coveted pick-up away before setting it alight as well.
Australian brothers Jake and Callum Robinson and American friend Jack Carter Rhoad failed to show up for an Airbnb booked in the Pacific resort of Rosarito.
The bodies were dumped in a 4m-deep well about 6km away, on top of a fourth body prosecutors say had been there much longer.
Three suspects are being held in connection with the case - two were caught with methamphetamine and one had one of the victims’ phones.
A criminal charge of forced disappearance, equivalent to kidnapping, has been laid against one of the three.
The man, Jesus Gerardo, has a criminal record of drug dealing, vehicle theft and domestic violence.
Jake and Callum’s father Martin Robinson thanked everyone involved in the effort to find out what happened to his sons and those who supported them, including the Department of Foreign Affairs, the Australian Federal Police and Australia’s ambassador to Mexico.
Martin Robinson also thanked Australian Foreign Minister Penny Wong, who made a telephone call to the couple this week.
Debra Robinson said her sons and their friend Carter Rhoad, were “young men enjoying their passion of surfing together”.
“We have been overwhelmed with the outpouring of emotions and support that we have received,” she said.
“We know they were truly loved and impacted many lives.
Mexican security forces frisked men at a checkpoint in Ensenada, Mexico. Photo / AP
“Callum was a loveable, larger-than-life character and considered the United States his second home,” she said.
“Known as ‘Big Koala’, he played professional lacrosse in the PLL (the US Premier Lacrosse League) and represented Australia in the world championships.
“His brother, Jake, was a happy, gentle and compassionate soul who was pursuing a career in medicine.
Mexico’s Foreign Minister Alicia Barcena also offered condolences to the men’s family as surfers in San Miguel held a paddle-out in tribute to the trio.
More than 100 people also gathered for a vigil in San Diego, where Callum lived.
In 2016, Adam Coleman and Dean Lucas - two surfers from Perth - were killed while travelling through Sinaloa.
