TIJUANA, MEXICO: Three bodies were identified by relatives Sunday as those of two Australians and an American shot dead during a suspected botched robbery during a surfing trip to Mexico, authorities said.

The corpses were found with bullet wounds to their heads, according to officials in crime-hit Baja California state, suggesting an execution-style triple homicide.

The news confirmed the worst fears of the families and friends of holidaying Australian brothers Callum and Jake Robinson, and their American friend Jack Carter.

The trio were believed to have been murdered during an attempt to steal their pick-up truck, state prosecutor Maria Elena Andrade said at a press conference.

The vehicle -- which had been burned -- was found nearby.

The bodies “all have a hole in their head made by a firearm projectile,“ Andrade said, adding that the friends had previously visited Mexico several times without any problems.

The state prosecutor’s office later confirmed in a statement that the bodies had been formally identified as those of the missing surfers.

Three suspects, two men and one woman, have been detained on suspicion of involvement in the case, according to prosecutors.

One of those arrested has a history of violence, drug dealing and robbery, officials said.

Investigators said earlier that the bodies were recovered from a cliff-top shaft in an “advanced state of decomposition.”

Another corpse found at the site had been there longer and was unconnected to the others, officials said.

AFP journalists saw authorities use a pulley system to extract the mud-covered bodies from the shaft on Friday near the town of Santo Thomas, about 30 miles (45 kilometers) southeast of Ensenada.

- ‘Tragic loss’ -

The Australian brothers’ mother, Debra Robinson, had sounded the alarm on a Facebook page for Baja California tourists several days ago, after the young men dropped out of contact.

“Reaching out to anyone who has seen my two sons. They have not contacted us since Saturday 27th April,“ she wrote, attaching a poster from friends desperate for news of their whereabouts.

A missing poster shared on social media said Callum Robinson was 33 and his brother Jake was 30. It named their friend as Jack Carter Rhoad, aged 30.

Callum Robinson’s Instagram page showed several images from the trio’s Mexico trip: enjoying beers with their feet up in a bar, lazing in a jacuzzi, eating roadside tacos, looking out at the surf.

Six-foot-four (1.93 meters) Callum had played in the US Premier Lacrosse League, which left a message on its website saying the lacrosse world was “heartbroken by the tragic loss” of the trio.

“We offer our hearts, support and prayers to the Robinson and Rhoad Families, as well as all who loved Callum, Jake, and Jack,“ it said.

Jake Robinson was a doctor in Perth, according to Australian media.

Baja California is known for its inviting beaches, and its resorts are popular with US tourists, partly because of their proximity to the border.

It is also one of Mexico’s most violent states because of organized crime gangs, although cartel activity doesn’t commonly affect foreign tourists.

Dozens of surfers protested in Ensenada on Sunday with messages written on their boards including “beaches, security, freedom, peace” and “no more deaths.”

The latest case echoes that of two Australian surfers who were murdered and their bodies burned while traveling in the northwestern Mexican state of Sinaloa in November 2015.

Criminal violence in Mexico has claimed 450,000 lives and led to more than 100,000 disappearances since the end of 2006, when the government launched a controversial anti-drug strategy involving the military.