The trial of two Myanmar nationals, accused of killing two British tourists in Thailand has begun, despite fears about the manner in which the crime was investigated. The trial, which was originally scheduled to start in February, was unexpectedly brought forward, the BBC reported.

Zaw Lin and Win Zaw Htun, both 21, have been charged with killing British tourists Hannah Witheridge, 23, from Norfolk, and David Miller, 24, on the Thai tourist island of Koh Tao in September. They also face robbery and rape charges. The two suspects had initially confessed to the murders, but withdrew their confession and alleged that they had been tortured by Thai police while in custody.

Human rights group Amnesty International called for an independent investigation into what it called “mounting allegations of torture and other ill-treatment by police,” in relation to the case. Police deny the allegations of torture. There were also concerns that the investigation was carried out in a slipshod manner, with tourists allowed to walk through the crime scene and improper forensic procedures being followed.

In addition, the concern is that the suspects are being made scapegoats by authorities because of their Burmese ethnicity. In the aftermath of the murders, foreign nationals were also immediately blamed for the crime because, a police spokesman claimed, “Thais wouldn’t do this,” according to Time

An editorial in the country's Bangkok Post newspaper described the investigation as a “farce,” characterized by a “total lack of professionalism” on the part of the police, adding that the targeting of Burmese suspects was motivated by “rampant ethnic prejudice.”

Pavin Chachavalpongpun, an exiled Thai political analyst at Kyoto University in Japan, told Al Jazeera that the authorities' motivations were possibly financial also. “The aim perhaps [was] to protect the tourism industry,” he said.

Concerns about the manner in which the case was being handled led British Prime Minister David Cameron to pressure Thailand's Prime Minister Prayut Chan-ocha at a summit meeting to allow British detectives to review the case, according to the Guardian. Their review has not been made public.