Initially one suspect confessed but two others denied.
But after a grueling daylong interrogation after the first suspect who confessed implicated his colleagues.
The two later admitted to the crimes.
Originally, two of the three suspects, all Arakanese from Arakan state in Myanmar, were apprehended by police early in the morning hours.
These two men were currently being employed as waiters in a restaurant on the island.
The arrest came after police obtained an image captured by a closed-circuit TV camera in 7-Eleven convenient store showing the three men entering a convenient store and purchasing cigarettes and alcohol and then proceeding to a long on the beach close to the actual crime scene.
The LM cigarettes which one of the suspects purchased were the same as the same brand of cigarette butts the forensic police collected from the scene.
The DNA test of the cigarette butts matched those found in the body of Ms Hanna Witheridge, 23.
On being arrested these two men admitted to sitting on said log and consuming alcohol and playing a guitar but denied having any involvement in the murders.
Police officers then led the two to a safe-house where they were intensively interrogated.
While this was going on another team of police officers arrested the third man at a Surat Thani municipal pier after it was discovered that he had boarded a boat and left Koh Tao Island late last night.
He was escorted to 8th Region Police headquarters for questioning.
Comparing his features to images captured on CCTV, police were able to ascertain that he was one of the three men in the footage.
He had recently dyed his hair black when originally his hair was dyed blond.
Some blond strands of human hair were found at the scene and were kept as evidence. Police are awaiting DNA test results to confirm their case.
Later in the day, Pol. Lt. Gen. Jakthip Chaichinda, the acting Royal Thai Police deputy commissioner, revealed that the three men had admitted to having committed the crime.
Meanwhile the acting assistant commissioner of the Royal Thai Police, Pol. Lt. Gen. Panya Mamen, identified the three Myanmar workers to the media Win, Mao and Sor and it was Win who first admitted to the crime.
On the night of the incident, Win revealed that he and his two accomplices were drinking, singing and playing the guitar approximately 65 meters from the murder scene.
They sang songs in the Yakai (Arakanese) dialect which tallies with eyewitness accounts that on the night of the murder, some people had seen Burmese men playing the guitar and singing at that spot.
All eyewitnesses stated that the songs were neither in Thai nor Burmese language but no one could make out the dialect.
At this point, the police managed to have an Arakanese waiter who worked at a Bungalow nearby the scene as witness. He told the police that the group of men singing and playing guitar are Arakanese from Arakan state in Myanmar. The police then started to clandestinely follow the group’s movement.
Win went on to say that later on they had seen the two British tourists walking towards a cluster of rocky reefs and were romantically embracing and cuddling each other.
Win stated that he was curious and grabbed a garden hoe and went to sneak a peek of the couple making out.
He admitted to being sexually aroused and along with his two accomplices had used the hoe to beat the male tourist and then dumping his body in the sea. They then proceeded to rape the woman and finally killing her by hitting her with the same garden hoe.
They then disposed of the murder weapon which was later found by police.
Police have collected the DNA samples of all three men the test results are expected to be revealed tomorrow.
Pol. Gen. Somyos Phumphanmuang, the commissioner of the Royal Thai Police, flew to Koh Tao later in the day to personally question the men and following that, formal charges will be filed against them.