The Taiwan High Court has fined a local man previously convicted of adultery a further TW$1.1 million (US$33,400) after being caught continuing to sleep with his 33-year-old Vietnamese mistress.

The 58-year-old man surnamed Huang, a former shareholder of a renowned fish-ball stall in New Taipei City, had an affair with the Vietnamese migrant worker surnamed Nguyen, who then gave birth to a son, Taiwan Apple Daily reported.

The affair was revealed in 2015 by Huang’s wife who became suspicious because her husband went out frequently with Nguyen’s child. The wife learned that her husband was the biological father according to a DNA test conducted in August.

The wife was furious, after being rejected for more than 10 years with her husband claiming to have erectile dysfunction, filed a lawsuit against Huang and the mistress for committing offenses against marriage and family. The pair was found guilty and jailed for four months (or pay a fine of TW$120,000).

However, the wife presented the High Court with evidence that the pair continued their affair – records of erotic talk during sexual activity between Huang and Nguyen in a car.

Huang’s wife sought compensation of TW$10 million from the pair, who pleaded guilty to adultery. The court ordered them to pay a fine of TW$1.1 million as compensation.

Meanwhile, Nguyen filed a lawsuit against Huang’s wife for using instruments or equipment without reason to watch or eavesdrop on other people’s private activities, as she put a voice recorder in Huang’s car for more than six months despite the fact the pair had admitted adultery to the police.

The prosecutor looks set to press charges against Huang’s wife as a preliminary investigation suggests her action to gather evidence against her husband and his mistress was excessive.