Shocking CCTV footage shows the moment the gunman shot Tony Kenway, 39, with a single bullet in his right eye as he opened the door to his posh sports car.
The expat businessman, from Southampton, was executed at around 10.20am local time this morning in the city of Pattaya, in south Thailand.
Cops are now hunting for the suspect who is believed to be a hired hitman linked to the criminal underworld.
Video of the shooting shows the Brit dad get into the parked red Porsche Cayenne GTS 4×4 near Mabprachan Reservoir.
Two men on a Honda Click motorbike following Kenway before they approached him as he sat in the car.
It is understood Mr Kenway. who was married to 32-year-old Pans Kenway, was about to drive home after visiting a nearby gym when the gunman opened fire.
In the footage the gunman is seen walking away calmly before fleeing on a motorbike.
Medics rushed to the scene in the parking lot at front of Sanit Sports Club Co, but Mr Kenway could not be saved.
Police Colonel Jirawut Tantasri said: ”There was a motorbike waiting and the killer escaped with another person riding it. There are two people we are looking for.
”One bullet went through Mr Kenway’s right eyebrow into his head.
”We believe there was a conflict of interest in a business that Mr Kenway had been involved in. We know nothing more than that.”
His older sister Kirsty Kenway, 31, has paid tribute to her brother who had a “brilliant” life in Thailand and “did a lot for charity.
She told MailOnline: “I don’t really know what happened to my brother. He’s been in Thailand for years and he’s been happily married for five years.
“We speak quite regularly and I visited him over Christmas. We had an amazing time, taking the kids to water parks and he spent a lot of time with his niece. He loved being with his family.
“He did a lot of work in IT and was a big fan of sports cars, he was a petrol head.
“Pans [his wife] is brilliant and she was the light of his life. She’s devastated by what’s happened.”
Police described the killer as a chubby man, wearing a white T-shirt and a black jacket, sports shoes and a cap that partly hid his face.
Kernway’s wife Somporn, 32, told police her husband had set up a company doing website design at Jomtien Beach.
He lately had a business conflict with a shareholder, but she did not know if this was the motive for the murder.
Police were examining footage from security cameras in the area and questioning more witnesses.
A spokesman for Nong Prue Polcie in Pattaya said: ”We have started an investigation and we are looking for the attackers.”
The victim’s body was sent to Bang Lamung Hospital for a post-mortem examination.
The Foreign Office confirmed a British national died in Pattaya earlier today and it is providing consular assistance to his family.
A spokeswoman said: “We are in contact with the family of a British man following his death in Pattaya, Thailand.
“Our sympathies are with them at this difficult time. We are in touch with the local police.”
Staff at the Saint Sport Club gym that Tony had been visiting before he was gunned down paid tribute to the ”lovely man”.
Receptionist Nong Pheung said: ”Tony had been here in the morning. He was a very nice, lovely man. He was always happy and friendly.”
A statement for Saint Sport Club added: ”We are very sad to announce the death of Tony Kenway who lost his life this morning.
”We would like to offer Tony’s family and friends our deepest sympathy and condolences at this difficult time. Rip Tony.”
It comes after a British tourist tragically drowned on a paradise island in Thailand after going for a swim while drunk.