Heartbreaking engagement photos show California surfer who was murdered in Mexico with the fiancée he was due to marry in three months

The American man who was gunned down alongside two Australian friends on a surfing holiday in Mexico was just weeks away from getting married, his devastated friends have revealed.

Jack Carter Rhoad, 33, was found dead on Saturday with a single gunshot wound to his head alongside his friends in an abandoned well overlooking the ocean outside Rosarito in Baja California.

The recruitment worker from San Diego was due to marry his fiancée Natalie Wiertz this summer - and had joined Australian brothers Callum and Jake Robinson for the road trip down the Pacific coast before his big day. 

Natalie, 32, had just enjoyed her bachelorette party in Florida's Key West in April, where was the beaming bride-to-be was pictured partying with her friends.

One friend of her friends, Aubrey Byers, has set up an appeal following the tragedy.

'We've created this GoFundMe page to rally support for Natalie during this unimaginably difficult time and provide essentials such as housing, food, transportation, and more,' she wrote. 

'Our hearts ache with grief for their families, friends, and community. Their presence brought immeasurable joy, love, and kindness to those around them, leaving a mark on our lives.'

Carter, originally from Atlanta, announced his engagement with his last ever Facebook post in July of last year.

The pictures show Natalie screaming with delight as he kneeled down on a beach at sunset to slip a ring onto her finger.

And the timer is still ticking down on the webpage for what was to have been their wedding this August in Columbus, Ohio.

Carter had visited Mexico throughout his adult life after volunteering for a medical mission in Guatemala at 19.

'Obstacles are just opportunities in costumes,' he wrote on his LinkedIn page. 'They can be scary or they can be fun just depends on how you look at them.

'Building genuine relationships is one of the most rewarding things in life, and I feel humbled every day by the people who surround me.'

Natalie, a clothing designer for Vanity Fair Brands in San Diego, looked radiant as her upcoming wedding was celebrated by friends in the Florida sunshine.

Carter had joined his friends for the road trip south after the two brothers enjoyed a weekend at the Coachella Festival.

Callum was based in the US where he was an accomplished lacrosse player known as 'the Big Koala', and his brother Jake, who worked in regional hospitals across Australia, had flown out to San Diego two weeks ago to visit him.

Earlier, Daily Mail Australia revealed that Callum's devastated girlfriend Emily Horwath shared a heartfelt tribute on social media.

'You are one of one,' she captioned a photo of the couple sharing a kiss.

'I will love you forever.'

She also posted an Instagram story which said: 'My heart is shattered into a million pieces, I don't have the words right now.'

'This world lost one of its kindest, silliest and most genuine of souls this week. Rest easy. I miss you.'

The three were just a few days into their vacation when they disappeared on April 27.

In social media posts shared by Callum just before they vanished, the trio was seen relaxing at Rosarito Beach, where they were said to be surfing and camping as they moved up and down Mexico's west coast.

They reportedly planned to move on to Ensenada, about 50 miles (80km) down the coast, but concerns were raised when they failed to check into an Airbnb on Sunday.

Police said they found three abandoned tents south of Ensenada, which were splattered with blood, according to local media.

The brothers' mother issued a desperate plea on social media after the group failed to turn up at an Airbnb they had booked in Rosarito.

Mexican authorities also found shell casings at the campsite where the three men were last seen with further investigations leading them to the well about 2km away.

Three bodies, as well as a fourth body believed to be a local rancher, were discovered on Saturday in the clifftop well overlooking the ocean.

It is believed the rancher's body had been there for much longer and his death is not believed to be linked to the three young men.

It took rescuers up to 20 hours to pull the bodies out of the well, with physical characteristics, including hair and clothes, matching the three men.

Mexican authorities said bandits attacked the three to steal the tires off their truck before killing them all and dumping their bodies.

But the style of the slayings - a single gunshot to the head - has sparked fears locally about the possible involvement of drug cartels, which are rife in the region.

It is believed the region is riven by turf battles between the Sinaloa and Jalisco New Generation cartels, in addition to other groups.

In June last year, the city's mayor, Montserrat Caballero, announced she had decided to live at an army base for her own safety after receiving threats.

Three Mexicans have already been arrested over the deaths but authorities are not ruling out further accomplices with possible links to organized crime.

'We cannot rule out the possibility that there are additional individuals who were involved in this incident,' local Attorney-General María Andrade Ramírez said.

She added that the victims 'all have a hole in their head made by a firearm projectile'.

The Baja California Forensic Medical Service released the autopsy results as heartbreaking footage emerged of the Aussies' parents leaving Ensenada Forensics Lab after identifying Callum and Jake's bodies.

Three Mexicans, Jesus Gerardo Garcia Cota, alias El Kekas, his girlfriend, Ari Gisel Garcia Cota, and his brother, Christian Alejandro Garcia, were arrested on Wednesday and charged with forced kidnapping.

Ms García Cota, 23, reportedly had one of the missing men's mobile phones.

It is understood police were able to make the arrests after one of the brothers' mobile phones was turned back on, and pinged a local mobile tower.

All three suspects were found in possession of an assortment of methamphetamines and other illegal drugs, according to local outlets Zeta and Talk Baja.