Polprom Watcharasirinan, husband of senior Office of Insurance Commission (OIC), confessed to his mother to killing his wife, Pisutthinee Watcharasirinan, who was 7 months pregnant.
Mrs Pisutthinee was found dead in her apartment with multiple stab wounds on Saturday.
Police presented evidence indicating the last person to have seen the victim alive was her husband, Polprom Watcharasirinan, who disappeared with the couple's two daughters after the victim was killed.
The husband, now suspected by officers from Phahonyothin Police Station as the killer, has been taken into police custody for interrogation, but he was unable to speak coherently.
Earlier today, the suspect's mother, Chantanee Watcharasirinan, went to the Phahonyothin police to inform them of her son's confession.
She said her son told her that he had killed his wife on an impulse, and did not know what he was doing.
The victim's mother told the police that 20 years ago, the suspect was addicted to strong sleeping pills, Domicom, and was hospitalised before getting married.
Afterward, the suspect lost all contact with his family.
Meanwhile, a talk with the victim's two daughters showed that the girls thought that their mother had been asleep.
The suspect has been taken to the Forensics Department for fingerprint samples and DNA verification.