Chamlong Phummalai was arrested on Monday at a house belonging to a relative of his wife in Ang Thong's Pho Thong district for the March 28 killing of Wassana Burakorn, 37, an education official.
Wassana was shot dead in the compound of the Khurusapha (Teachers Council of Thailand) in Bangkok. Mr Chamlong had been reportedly romantically involved with the victim who wanted to break up with him after finding out he had a wife.
The victim had also filed a complaint against the suspect with police a week before the shooting over a motorcycle theft.
Police said Mr Chamlong admitted during questioning he had threatened Wassana the day before the killing when he asked her about progress in a 700,000-baht loan application she had made for him.
According to police, the suspect "sat down next to the victim, pointed to a gun he was carrying and asked her if she knew what it was".
The next day Mr Chamlong deflated her car tyres in anger when he saw her chatting with another man. When she later refused to answer his questions about the theft charge and the loan, he shot her three times, police said.
Mr Chamlong was taken Tuesday for a crime re-enactment at the Khurusapha compound. Family members of the victim, who were among the crowd watching the reenactment, shouted to police to press for the death penalty.
Metropolitan Police Bureau commissioner Lt Gen Sanit Mahathavorn, who ran the re-enactment, said police would oppose any bail request. He said police were waiting for the results of ballistic tests from the gun handed to them by the suspect.
Somchai Sornjin, 57, who drove the getaway car and took Mr Chamlong to a bus terminal, was charged with being an accessory to the crime. He was arrested earlier.-BANGKOK POST