An engineer was detained by the husband of a woman who recognised him as the person who she suspected of having taken an upskirt video of her almost a year ago.

The 37-year-old husband, a chef, followed Gu Wei Wei from Kovan Heartland Mall to Kovan market and food centre, where the accused was detained for trying to place his plastic bag containing his cellphone near a woman's skirt.

Gu, 29, a Singapore permanent resident from China, was jailed for six weeks yesterday on two counts of insulting the modesty of a woman at Cold Storage supermarket in Kovan Heartland Mall on April 29 this year.

Deputy Public Prosecutor Lee Zu Zhao said Gu had placed his mobile phone in a plastic bag and slit a horizontal opening at the side of it. He positioned the camera upwards, leaning it against the opening, and set it to video-recording mode.

He then approached an unknown woman and held the plastic bag underneath her skirt. He did the same thing to another woman at the supermarket.

When Gu was walking along the second level of the mall, a 39-year-old housewife spotted him. She recognised him as the person whom she suspected of having taken an upskirt video of her some time in May last year. She then called her husband while she continued to observe Gu from afar.

Her husband tailed Gu to Kovan market and food centre, where he detained Gu for trying to place his bag near another woman's skirt.

In mitigation, Gu, who was unrepresented, told District Judge Adam Nakhoda that he had lost his job because of the offence and brought shame to himself and his family.

The judge said the series of offences Gu committed that day did not appear to be the first time he had committed them. But since there was no charge against him over the May 2016 incident, he did not take that into consideration.

In another hearing yesterday, car salesman Jason Toh Han Soon, 33, was jailed for 18 weeks after he admitted to 13 of 38 charges of intruding into the privacy of a woman. A total of 428 upskirt photos, taken from Sept 22 to Dec 20 last year, were recovered from his phone.

He was detained by a 36-year-old woman on Dec 20 last year. She had seen him taking an upskirt photograph of an unknown woman on an escalator at Dhoby Ghaut MRT station, and called the police.

The maximum punishment for insulting the modesty of a woman is one year's jail and a fine.