Garry was arrested with 18 grams of crystal methamphetamine hidden in his pocket, and drug-related equipment, including scales, on Saturday night in Phuket, the Phuket News reported.
The 52-year-old dive instructor for Raya Group Asia was busted in a police sting operation during a deal in a room at the Chalong Villa Resort and Spa.
Crystal methamphetamine, also known as ya ice, is a class one drug.
The deal was set up by a 25-year-old Thai man who had previously been caught by police for drug possession.
The man said Halpin had purchased crystal meth from him with the intention to sell it to tourists and teenagers.
The former Aucklander, who has lived in Phuket for 15 years, allegedly had the equivalent of about five “8 balls”, a measure of 3.5g, of the drug when arrested.
The Phuket Wan Tourism website reported tonight that Halpin said he had not confessed or signed a statement. He denied ever selling drugs to tourists.
He is expected to appear in court tomorrow.
Halpin was in Phuket in 2004 when the Boxing Day tsunami struck the popular Thai resort area. He spoke of snorkelling with his young daughter, now 13, the day before the event.
The New Zealander was well-known in Chalong, including to police, he joined the tourist volunteer police force in 2010.
The Phuket Tourist Volunteer Organisation supported local police activity and aimed to ensure international travellers to the area were protected from common tourist scams.
A Phuket expat who knew Halpin told the Phuket News the arrest was a shock.
“He was a nice guy, and very helpful. I’ve never heard anyone say a bad word about him.”
Halpin told news reporters that he had not signed a statement or made a confession, nor had he ever sold drugs to tourists. He is most likely to appear in court tomorrow, to face charges that could get him life imprisonment if convicted.
About 90 New Zealanders are behind bars in 26 countries around the world, according to the Ministry of Foreign Affairs and Trade.