A woman was arrested in Bangkok on Monday over an alleged hitman plan targetting her husband, who died in Maha Sarakham in April.

Only days before his death from "natural causes" he had survived an attempt on his life by a gunman in Bangkok, police said.

Wannipa Hamala, 37, was arrested at her house in Ram Intra area after a police investigation into the death of her husband, Pichit Kleepchinda, a 44-year-old businessman.

Pichit died at home in Maha Sarakham in mid-April. On April 8 he had been shot at in Bangkok's Wang Thong Lang district. His death certificate stated he died of natural causes. His sister suspected foul play and went to the police.

Police on Monday also arrested two men, identified only as Sarote and Weerapat, in connection with the April 8 shooting.

Mr Sarote allegedly procured the gunman, the gun and the motorcycle used in the attack. Mr Weerapat drove the motorcycle the gunman rode on. A man named Nattapol is the alleged gunman. He remains at large.

According to police, Ms Wannipa and her husband had argued on several occasions over his alleged infidelity. Sometimes the arguments ended in violence.

Police believed Ms Wannipa looked for a hitman using an online app and contacted the three men in late March via a chat platform.

Their chats allegedly discussed hiring a hitman, the use of a gun, how to identify the target and a possible location for the attack. They also agreed to meet on April 1.

Ms Wannipa transferred a total of 45,000 baht to the alleged gunman from April 1-7 as an advance payment, and 33,000 baht to Mr Sarot on April 6 for procuring a gun and a vehicle, according to police.

She then asked her husband to meet her at a restaurant in Ram Intra area of Bangkok on April 8, so the men could identify their target. Pichit was shot at that night, but escaped unhurt.

Meanwhile, Mr Weerapat, who drove the motorbike on April 8, said that when he was hired he was unaware he was driving a gunman, until the attack occurred.

He said he was paid 4,000 baht to drive around a man who said he was looking for his girlfriend, and that he tried to drive away as the gunman was about to fire. The shots missed.