Former café owner-turned-politician Somyos Suthangkun was shot dead on Monday night at a restaurant car park in Khlong Tan area after dining out with his wife.
Somyos, 62, owned the popular Phra Ram 9 café before it was closed and was a former Democrat Party list candidate.
He was about to get into his car, parked at the back of the Heng shark-fin soup restaurant on Patthanakan Road in Suan Luang district, where he had dined with his wife.
The two attackers arrived on a motorcycle and fired three shots at him about 9pm. He died on the spot.
A security camera filmed the two men waiting for Somyos for a while, then walking over to him and one shooting him in the head. The men were each described as 160-170 centimetres tall. Both wore caps that hid their faces.
After preliminary inquiries, police settled on three possible motives for the murder - a 4-million-baht gambling debt, a 25-million-baht legal case and a Rama 9 land dispute, according to Pol Gen Riangsak Charitek, a deputy national police chief.
Somyos was owner of the Rama 9 café, which was known for live performance by leading Thai comedians. Business plummeted after the 1997 economic crisis and the café later closed its doors.
Somyos later stood for election on the Democrat Party list and was the president of the Association of Entertainment Operators of Thailand.