The Daily Telegraph said Stephen Ashton, 22, who was killed at a bar, was likely caught in crossfire after an argument broke out between two groups of youths.
Police said the suspect, Ekkapan Kaewkla, 26, was in possession of a homemade gun when he was arrested.
Police said they will likely charge Kaewkla with manslaughter.
The Telegraph said Kaewkla admitted to fighting at the bar but denied shooting Ashton, who was taken to Bandon International Hospital and later pronounced dead.
Witnesses said a fist fight broke out between two groups at 4 a.m. Tuesday.
"Stephen was not involved in the fight," Police Col. Kittakarn Kramothong said.