BANGKOK - A lawyer for two Myanmar migrants accused of murdering a pair of British holidaymakers on Thursday said key witnesses are too afraid to come forward, hampering his clients' defence as they prepare to enter a plea.
The men stand accused of murdering David Miller, 24, and raping and murdering Hannah Witheridge, 23, on the Thai diving resort of Koh Tao in September.
Zaw Lin and Win Zaw Tun, both migrant workers aged 21, were formally indicted for trial on Thursday and are due to enter a plea on Monday, according to prosecutors on nearby Koh Samui, where the case will be heard.
"The court will ask the defendants whether they confess or deny the charges," chief prosecutor Paiboon Archavanuntakun told AFP.
The pair -- who did not appear in court on Thursday -- are also accused of battery and illegal entry to Thailand, among other charges, he added.
They were arrested in October after police said they had found the men's DNA on Witheridge's body and that they had admitted to the crimes.
But Zaw Lin and Win Zaw Tun later retracted their confessions, alleging they were obtained under duress.
Their families and legal team have also protested their innocence, saying the men have been made scapegoats by a police force desperate for a quick conclusion to a crime which raised fears over tourist safety in the kingdom.
One of the two men's lawyers told AFP his clients vulnerable immigrant status meant witnesses were scared of testifying or willing to come to his defence.
"This case is not fair... they were migrant workers so witnesses do not dare to testify (for the defence)," Nakhon Chomphuchat, head of their Thai legal team, told AFP.
"We have many disadvantages... we still have not seen the prosecutors' evidence, we just have to fight as best as we can," he added.
On Tuesday the defendants submitted a letter to the court urging witnesses to come forward to help clear their name.
Migrant workers, particularly from neighbouring Myanmar and Cambodia, are often accused of crimes in the kingdom.
Rights groups say they lack fair access to Thailand's already murky legal system.
'My son is not a murderer'
Questions over the police probe prompted British Prime Minister David Cameron to urge his Thai counterpart, Prayut Chan-O-Cha, to allow Scotland Yard detectives to review the Thai case.
A team of British detectives visited Thailand in November but are yet to reveal their findings.
On Thursday the father of Win Zaw Tun repeated his belief in his son's innocence.
"Our son is not a murderer, but he has been locked up like a criminal," he told AFP in Myanmar's commercial capital, Yangon.
"I want the Thai government to capture the real criminal. Knowing my son is in jail makes me suffer terribly. If I could swap with him I would," he added.
The grisly murders delivered a fresh blow to the kingdom's image as a tourist haven after months of political protests that ended in May's army coup.
Martial law is still in place across the country, and tourist arrivals have eased off on last year.