Police said two of the suspects, Pongpitak Tapsawang, 29, and Prachak Muenjinda, 50, had confessed to robbing and murdering Michael Raymond, 68 and Suchada Baokhamdee, 52, at the Jack Beach Resort. They worked in the resort as security guard and cook respectively.
The third suspect, Jakkarin Yuyen, 30, denied the charge. Police alleged that Jakkarin visited the resort to borrow money from Prachak before deciding to rob the couple.
A maid at the resort found the badly beaten bodies of the couple Tuesday afternoon in their bungalow.
Police said the bodies were badly beaten and their belongings were ransacked. The suspects told police that they robbed the couple of Bt2,000, a mobile phone and an ATM card.
According to initial investigations, the couple checked in to the resort on Monday. The Briton had lived in Khon Kaen for about two years since marrying Suchada.
Prachuab Khiri Khan Governor Veera Sriwattanatrakul said that the gruesome murder badly tarnished the province and its tourism business. Resorts in the province should from now on be equipped with security cameras to ensure safety and help police if crimes occurred.
Meanwhile Thawatchai Daengchum, president of Huay Yang Tambon Administrative Organisation, said the crime had shocked people, as the beach area, which is home to several resorts, is known to be peaceful and is popular with foreigners.