A male relative of a slain 83-year-old Japanese man's Thai wife has been arrested and implicated in the killing.
The man's body was found on Tuesday in his home in Angthong's Wiset Chai Chan district, and it is alleged that the wife had taken out a contract on his life.
The Provincial Police Region 1 is scheduled to hold a press conference on this case today.
Angthong investigation superintendent Pol Colonel Seri Songkit said yesterday that Sampan Jaemjaeng, 47, was arrested while travelling on a public bus yesterday.
The bus had stopped at a petrol station on Mitrapap Highway in Sara Buri province.
Sampan is accused of stabbing retired businessman Kasuo Yoshitoka to death on Monday night.
A police source said Sampan - former slaughterhouse worker with a prior conviction of a robbery-murder of an elderly person in Sing Buri province - initially confessed to the killing along with another man.
He claimed he had been hired by the victim's wife Paranee Napadol, 48, to whose sister he is married.
He claims she promised him Bt40,000 (S$1,600) for the killing.
Wiset Chai Chan police yesterday summoned Paranee and another 40-year-old man for information - both of them have maintained their innocence.
Police also had rescue workers dive down the victim's back-yard well where the suspect claims to have dumped the knife and ladder used in the murder. The divers found the ladder, but the knife was later found in Sampan's bag.
Meanwhile, Paranee's younger brother Theerapong defended his sister, saying there was no reason for her to have had her husband killed because the couple had a loving relationship.
He said Sampan might be implicating her out of anger because she had refused to become a guarantor for the purchase of a motorcycle.