Defense witnesses for two Myanmar migrant workers accused of murdering two young British tourists on a Thai resort island have testified that torture and intimidation are commonly used by local investigators.

The three witnesses who testified Thursday — a member of the National Human Rights Commission, a lawyer and a fellow migrant worker — all described how a violent and abusive system caused the two defendants to make confessions they later recanted.

Defense lawyer Nakhon Chompuchat said it was a problem for his clients' case that other workers were too scared to testify.

The bodies of David Miller and Hannah Witheridge were found Sept. 15 last year on a beach at Koh Tao. Autopsies found both suffered severe head wounds and Witheridge had been raped.