By Brad Ryan, ABC
Photo: Instagram/Supplied
Mexican authorities said they believed two Australian brothers and their American friend were shot dead by thieves who were trying to steal their car for its tyres.
Three people remain in custody over the disappearance of Jake and Callum Robinson, originally from Perth, and American Jack Carter Rhoad, who were camping in Mexico's north-west.
Three bodies were recovered from what had been described as a well in the area on Friday, local time. They are yet to be formally identified, but authorities believe they are the missing men.
All three died from gunshots to the head, according to the Baja California Forensic Medical Service.
The attorney-general for the Mexican state of Baja California, María Elena Andrade Ramírez, told a press conference on Sunday, local time, that authorities' early theory is the men were killed in a robbery gone wrong.
She said it appeared the attackers were passing through the area when they decided to steal the campers' ute, which they wanted for its tyres, and they shot the campers when they resisted.
A 23-year-old woman, her partner and his brother were detained last week by Mexican authorities.
One of the men, named as Jesús Gerardo García, now faces a "forced disappearance" charge. He has a history of drug dealing, domestic violence and vehicle theft, Andrade Ramírez said.
His brother and the woman are in custody for possession of methamphetamine.
The woman was allegedly found with a mobile phone belonging to one of the Australian men.
The attorney-general said investigators were confident more than three people were involved in the attack.
She could not rule out a connection to organised crime, she said. Violent drug cartels are rife in Baja California.
Family of the Australian men have travelled from Western Australia to Mexico.
Andrade Ramírez said they would be asked to identify the men at a facility in Tijuana.
DNA tests would only be carried out if the family members could not identify them by sight.
- ABC