Updated

Thai prosecutors say they have indicted two Myanmar migrant workers for the murder of two British tourists on a resort island.

The bodies of David Miller, 24, and Hannah Witheridge, 23, were found Sept. 15 on a beach on Koh Tao, an island in the Gulf of Thailand known for world-class scuba diving. Autopsies showed both had suffered severe head wounds and Witheridge had been raped.

Police said in October that DNA evidence proved the suspected killers were two men from Myanmar who were working illegally in the country — Win Zaw Htun and Zaw Lin, both 21.

The two claim that their initial confessions were extracted by beatings and threats.

Britain's Foreign Office has expressed concern to Thai authorities about whether the investigation was conducted properly.