Taichung lawyer Liu Pei-yuan (
Surveillance camera footage released by Taichung police shows a man lunging at the victim with a knife more than 10 times while her mother attempts to stop him.
Police said Liu, 41, is a Taichung lawyer and a lecturer at Taichung's Tunghai University. He is also a doctoral student at National Taipei University's law school.
The victim, Chang Hsiu-feng (
Liu turned himself in two hours after the murder.
Liu said he had a kitchen knife with him when he began following Chang and her mother on Friday morning at 10am, police said.
At 2pm, when Chang and her mother entered a bakery, Liu entered the shop to confront Chang.
The surveillance footage shows Chang leaving the shop, followed by a man who started stabbing her in the back. Chang's mother tried to stop the attacker, but to no avail.
Chang was rushed to a hospital, where she died.
The police said Liu told them he had had an extramarital affair with Chang for four years and had been very fond of her.
He had wanted to divorce his wife and marry Chang, police said.
Liu said he eventually divorced his wife earlier this year by agreeing to give her almost all of his property.
However, Chang told him she wanted to end the relationship because he had no money now, Liu told the police.