A man fatally stabbed his senior in Saimai Soi 8 and surrendered to police, alleging revenge after the victim stole his cannabis pipe and threatened to shoot him.
The case involves Mr. Kachaphat Thammasit, or Best, 35, who illicitly sold kratom juice and was stabbed by Mr. Kritthaphon Muangmai, or Bank, 25, with a knife under the left breast and in the center of the chest, dying at a shop near Saimai Soi 8, Saimai district, Bangkok, on the evening of 5 Feb 2026. The cause stemmed from longstanding anger, as Bank accused Best of theft and they had a prior assault case at Saimai Police Station last year.
At Saimai Police Station at 11:30 a.m. on 6 Feb 2026, Mr. Kritthaphon Muangmai, or Bank, 25, the suspect, surrendered to Police Colonel Nathatphong Kiram, Superintendent of Saimai Police, along with Deputy Superintendent Police Lieutenant Colonel Ditsayadech Yimyaem and Investigating Officer Lieutenant Colonel Sorakrit Naksut. He brought a 12-inch folding knife and a green Honda Giorno motorcycle, Bangkok registered, as evidence. The Min Buri Criminal Court issued arrest warrant no. J.239/2569 on 6 Feb 2026, charging intentional homicide and carrying a knife in public without lawful cause.
Bank stated he works as a delivery rider and lives in the same housing project as Best. He claimed Best acted as a local boss selling kratom juice illegally. Last year, Best allegedly stole Bank's cannabis pipe, which angered him and led to a physical fight requiring police involvement. Best threatened to shoot him if they met again, deepening Bank's grudge. Before the stabbing, Bank saw Best leaving a convenience store, stopped his motorcycle, confronted him by asking, “Are you going to shoot me?” then drew a knife and attacked. Bank then fled on his motorcycle to visit his mother near Bhumibol Hospital before deciding to surrender.
After questioning, authorities took the suspect and evidence to Saimai Police Station for further legal proceedings.