Patrick Farrell, 61, is expected to face first-degree murder charges after being accused of killing his friend, bar owner Ernest Brennan.
Mr Brennan was stabbed to death early on Monday morning in the bar he ran with his wife in the Thai resort of Pattaya.
It also emerged Mr Farrell, from Derry, was grabbed by customers in the bar as he tried to flee.
The victim’s wife, Chantaneepaa Boonsap, the owner of Jimmy’s Place, told police her husband was drinking in the bar when Mr Farrell arrived. The pair started talking and drinking together and were with each other for some time.
Ms Boonsap claimed the suspect appeared rather drunk and said a disagreement broke out. The two men started arguing loudly. Other witnesses suggested the argument centred on a hotel and a taxi bill.
At this point, according to the statement, Mr Farrell is alleged to have pulled out a knife and plunged it into the victim’s neck. The 45-year-old Dubliner, who was sitting on a stool, fell forward onto the bar and was then stabbed again, this time in the back.
As the attacker attempted to flee, customers grabbed him and wrestled him to the floor, where he was held until police arrived.
Mr Brennan, originally from Howth in north Dublin but living in Thailand for some years, was rushed to Pattaya International Hospital, where he was officially declared dead.
Lieutenant Colonel Poonchai Churat, investigations inspector at Pattaya Police Station, said he received word of a stabbing at a bar on Second Road and raced to the scene at 1.30am on January 31.
At the bar, he met a man identified as Patrick Oliver Farrell, from Northern Ireland, being held by other customers.
Mr Farrell was taken to Pattaya Police Station along with the bloody knife found at the scene. He is currently in custody and is expected to face a charge of first-degree murder.