Two Myanmar men accused of murdering two British vacationers in Thailand went on trial on Wednesday in a case that caused outrage in Britain and raised questions about the competence of the Thai police and the treatment of migrant laborers.

British tourists David Miller, 24, and Hannah Witheridge, 23, were murdered last year on Koh Tao, or Turtle Island, a popular tourist destination in southern Thailand.

Thai police said in October that Zaw Lin and Win Zaw Htun, two 22-year-old migrant workers from Myanmar, had initially confessed to the killings. The confessions followed weeks of speculation and pressure on police to solve the murders.