A young Australian who suffered serious facial injuries when he was bashed by two Americans in Thailand is facing assault charges — and his family believe he is being unfairly targeted.

Jack Hansen-Bartel required three operations after he had teeth knocked out and his jaw bone shattered in an altercation in a nightclub while on a holiday on Koh Samui.

The two Americans involved, Raymond Chang and Ryan Wang, walked away from the fight unscathed.

"I just remember bleeding profusely — my gum bone [being] all shattered," Mr Hansen-Bartel told the ABC's 7.30 program.

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He said it started when he met Tiffany Mariko Turner at the beach earlier that day in June last year.

Both were students at international schools and had come to the Thai beach resort to celebrate the end of school.

"I was having the time of my life, I just graduated, I had my close friends, my uni friends, my brother — all celebrating, all looking forward to what the future held," Mr Hansen-Bartel said.

He said Ms Mariko Turner and their friends arranged to meet at a bar called Henry Africa.

"In Henry Africa, she leaned in to kiss me, we were kissing on and off," Mr Hansen-Bartel said.

He said Ms Mariko Turner then suggested they cross the road to a nightclub called Green Mango.

Chang, Wang claim Hansen-Bartel 'molested' girl

At Green Mango, Mr Hansen-Bartel met two American college students, Raymond Chang and Ryan Wang.

Mr Wang later gave this statement to police: "While I was partying with my friends I saw Jack Hansen-Bartel walk into the club, looking like he was drunk, walking into Tiffany Mariko Turner, who was one of my close friends."

Jack Hansen-Bartel says he was assaulted in Thailand. ( ABC 7.30 )

"Jack was really intoxicated and he couldn't stand straight and the way he sounded was clearly drunk," the statement read.

Mr Chang backed up his friend's story.

In his statement he said: "[Jack] couldn't walk straight, and walked into Ryan and Tiffany, who ... were dancing near each other."

Both men said Ms Mariko Turner was already at Green Mango with them and Mr Hansen-Bartel approached and started "molesting" her.

But CCTV footage from the Green Mango appears to contradict the men's evidence, showing Mr Hansen-Bartel and Ms Mariko Turner walking in together.

"You can see in the CCTV footage, [I] don't have a drink in my hand," Mr Hansen-Bartel said. "You can see that I'm standing straight, doing nothing."

At one point, Mr Chang approaches Mr Hansen-Bartel on the dance floor and speaks to him.

"He's saying, ah, 'this girl's with my friend, so back off'," Mr Hansen-Bartel said.

"I said 'yeah, no worries, I didn't know she was with anyone, I just met her anyway'."

The CCTV shows Mr Hansen-Bartel walking away. He joined his brother and friends at another bar, and later returned to Green Mango.

It was during this second visit to the bar that the fight happened, but it was not caught on camera.

"I just turn around and I see punches coming, from one guy," Mr Hansen-Bartel said.

"[I] get hit in the eye, fall down to my knees, try to get back up, before I can do anything I get hit again once more and then I pass out."

His friends, including Husam El Roumy, were on the dance-floor too.

"We turned our back on Jack and then when we turned back again Jack was already on the floor, unconscious," Mr El Roumy said.

"[He] couldn't speak and there's blood everywhere."

Mr Hansen-Bartel's brother and friends dragged him out of the club and called an ambulance.

The next day, the beaches of Koh Samui were abuzz with chatter. Mr Hansen-Bartel's friends found Ms Mariko Turner lying on the beach.

"And we just ask her simple question: if she knew about last night," Mr El Roumy said.

"And she told us that she did not know anything and she wasn't there and that she had no clue."

Assault charges laid, parents step in

Mr Chang and Mr Wang were initially charged with assault.

And that was when the parents got involved: Mr Hansen-Bartel's mother, Australian expat Annie Hansen, and Mr Chang's father, American businessman Raymond Nobu Chang.

"I have no words," Ms Hansen told 7.30. "My world just completely collapsed."

She said Mr Chang (senior) produced a document offering her 800,000 baht to drop the charges against the two boys.

Mr Chang (senior), who declined to speak directly to 7.30 because of the court case, provided that document.

Jack Hansen-Bartel's injuries after he said he was assaulted in Thailand. ( ABC 7.30 )

It offers Ms Hansen 800,000 baht, but he said that happened after she asked for 10 million baht.

Mr Chang (senior) wrote to 7.30 in an email: "Ms Hansen demanded that we pay her 10 million Thai Baht or else she would make sure the two boys 'rot in jail'."

Ms Hansen did not dispute asking for 10 million baht to compensate for her son's injuries.

From this moment forward, Mr Hansen-Bartel's case turned against him. Ms Mariko Turner turned up at the police station with Mr Chang (senior).

"The father said to me 'I have Tiffany Turner in this room and I think you need to know what your son's like'," Ms Hansen said.

"She (Tiffany) said 'your son is very terrible, he was dragging me into Green Mango bar, he was molesting me, he was falling over everywhere, and all his friends were trying to prop him up to stop him falling over'."

But when the CCTV shows Ms Mariko Turner and Mr Hansen-Bartel arriving together, his friends are not with them.

Ms Mariko Turner would not speak to 7.30 but her father John Turner emailed a statement: "Ryan and Raymond were not the instigator of the fight, Jack was."

"Jack was repeatedly told to leave my daughter alone, and Jack refused. Jack put his finger in Tiffany's mouth, unwelcomed, therefore Ryan directed him to not do so," the statement read.

There are differences between what Ms Mariko Turner told the police and what Mr Turner now says happened.

Ms Mariko Turner's police statement makes no mention of their earlier meeting at the bar Henry Africa.

Mr Turner now agrees his daughter was at Henry Africa, but said she was manhandled and forced to drink by Mr Hansen-Bartel.

He said she left and later bumped into him outside Green Mango.

Assault charges move to Hansen-Bartel

Six weeks after the initial assault charges were laid, Mr Chang (junior) and Mr Wang returned to court and later that day, Mr Hansen-Bartel was shocked to find he was being charged with disturbing the peace and street fighting.

Annie Hansen says her world has "completely collapsed" over the saga. ( ABC 7.30 )

In June this year, Mr Hansen-Bartel's charges were upped to assault and he was briefly taken into custody.

He is due in court in November and faces up to six months in jail. His mother is shocked. "He was a victim of a crime," Ms Hansen said.

"At no stage in the last year has he been treated as a victim of crime," she said.

Mr Chang (senior) said his son had been miscast.

"He is a good kid who stepped in to help a friend against an Australian who was hassling a girl," he said.

Mr Chang (junior) and Mr Wang never sought medical attention after the fight but a year later, Mr Hansen-Bartel still needs operations for three missing teeth.

Ms Hansen now feels abandoned by the country she adopted 15 years ago.

"I never dreamed in a million years that such a simple case would be amplified into such an amazingly horrible set of circumstances," she said.