Thailand is predominantly a Buddhist country but the majority of people in its three southernmost provinces, Pattani, Yala and Narathiwat are Muslims and ethnically Malay in origin. For the best part of a century, heavy handed efforts to integrate them into the wider Thai state have caused resentment and sometimes open rebellion.

This situation worsened markedly in 2001 when efforts by Thaksin Shinawatra, Thailand's then prime minister, to expand his political influence in the south, infuriated separatists. They responded with attacks on the Thai military and state employees, which in turn provoked a crackdown by the authorities.

By 2005 the army had imposed martial law on the southern provinces and a loose network of separatist groups were waging a brutal guerrilla war. Since then, nearly 4,500 people, mostly civilians, have been killed in tit-for-tat attacks and hundreds of people have been arrested and detained on suspicion of links to the insurgency. 

More recently the Thai government has been been pursuing a "hearts and minds" strategy to win the southern populace over. But the suspicious death of one of those detainees at an infamous army base has rekindled allegations from human rights groups that Thailand's military have been torturing prisoners.  

Filmmakers Orlando de Guzman and Andrew Marshall have been investigating the death of Sulaiman Naesa, just one of the many casualties of this conflict. Some of the images in their film may be disturbing.