They are hoping to see the same success everywhere criminal syndicates are found, said Central Investigation Bureau (CSD) acting chief Pol Maj Gen Thitirat Nonghanpitak.
Gen Thitirat led about 300 police to join military forces for the dawn operation on the resort island on Friday.
A team of 756 security officers, including commando police and soldiers, raided 26 spots believed to be hideouts of powerful people or criminals.
They arrested five suspects and confiscated 20 guns and 835 rounds of ammunition as well as three kilogrammes of kratom.
Gen Thitirat decided to look into criminal cases on the island after local businessman Panas Kao-uthai, 49, was gunned down in a restaurant early this month, apparently as a result of business conflicts among influential figures.
His death frightened people on the island, which is one of Thailand’s top tourist destinations.
Gen Thitirat was concerned that the high level of crime on the island was tarnishing the reputation of the island as a safe destination. Authorities were urged to speed up their probe.
During the operation on Samui, CSD officers and their counterparts from Provincial Police Region 9 also looked for the gunman who killed Panas, who was still at large.
On Friday night (March 20), Charoen Sisaeng, the suspected gunman, turned himself in to police for fear of being killed during the operation.
One day before the officers launched the raid, four other suspects in the Panas killing were arrested.
They are Samart Boonsin, who is alleged as a local influential figure; Chanai Sooksom, a former local politician; Chalit Boonsa, a businessman; and Chayut Kaewaram, another suspected gunman.
Clues were obtained from security camera footage, police investigators said. Their hunt for the killers went easily as they could be identified from camera footage as they were escaping.
The investigators soon knew there were two gunmen. They said one of them is Chayut, who was seen entering Mr Samart’s house.
What most attracted the police’s attention were allegations that Mr Samart had been at odds with Panas.
The officers nabbed Chayut as he was about to take a ferry off the island.
Police said the Ratchaburi native initially denied involvement in the murder plot, but later confessed after police backed their accusation with security camera footage.
His confession helped police to identify another alleged gunman, Charoen.
Police believe business conflicts in various projects with Mr Panas led to the murder. The three suspects denied being involved.
The investigation revealed Panas and the suspects who are business operators were arguing over real estate projects and revenues from a trade fair on a pedestrian street in Tambon Bo Phut.
Their conflict was so severe they allegedly threatened to kill one another.
The investigators believed the three suspects hired gunmen to kill Mr Panas because they were worried many local businesses would end up in the hands of Mr Panas who had good connections with investors outside the island.
The deadly conflict alerted Gen Thitirat to other mafia problems in Samui, so he ordered Friday’s crackdown on criminal activities. He was also responding to concerns expressed by tourists about the rising crime rate.
Pol Maj Gen Thitirat also vowed to “cut the mafia’s cycle” everywhere, particularly tourist destinations in Thailand, where crimes occur in the same way as Samui’s.
The approach involves raids on target areas as well as moving to block financial transactions of mafia suspects.
In the Samui operation, police from the Economic Crime Suppression Division and Technology Crime Suppression Division were also ordered to inspect the suspects’ mobile phones, computers, and business tax information to look for any irregularities.
Gen Thitirat took over the running of the CSD after the arrest of the previous boss, Lt Gen Pongpat Chayapan, on bribery, corruption and lèse majesté charges. Pongpat has received sentences totalling more than 30 years in jail.