Not only did Heng Li Ying, 29, betray other women by secretly filming them in the changing rooms of the True Fitness outlet at Suntec City Mall, but she also sold the videos for profit.

Yesterday, she was sentenced to 30 weeks' jail after admitting to three counts of intruding into the privacy of three women on April 19 and 26 in 2014. The identities of two of the women are not known.

Two other similar charges as well as one of having 23 obscene films were considered during her sentencing.

To promote the sale of her videos, Heng even offered free obscene videos.

Potential buyers would send her messages on the Sammyboy forum and transfer money to her bank account before she released the videos via download links.

The marketing executive earned at least $1,540 selling the videos, each lasting from less than a minute to about two minutes, to at least 22 people between early 2014 and May 7 the same year.

Deputy Public Prosecutor (DPP) Winston Man said Heng was able to use facilities belonging to True Fitness when she signed up for a two-year membership in 2012.

Some time in early 2014, she created an account with the username "gargar787" on Sammyboy, which is an online forum with sections that allow users to post and exchange sexually explicit material, including self-recorded sex videos and pornography.

As she had difficulties in holding down a permanent job then, Heng created a discussion thread labelled "Changing room peektures" to advertise videos depicting women in various states of undress, for sale at either 10 or 20 cents per second of footage.

The DPP said that after True Fitness was alerted to the sale and circulation of compromising videos of customers in its changing rooms, its staff lodged a police report on April 10 that year.

Seeking 16 weeks' jail per charge for Heng, DPP Man said she not only derived financial benefit from her offences, but also circulated the videos online.

Her lawyer, Mr Rajan Supramaniam, said his client was truly remorseful and regretted committing the offences which had ruined her life and career.

Pleading for leniency, he said Heng apologises to the victims and the court for her wrongful actions.

District Judge Chay Yuen Fatt agreed with the prosecution that this case was more aggravated than an earlier invasion of privacy case, and a higher sentence would be imposed.

Heng, who was allowed to defer sentence until June 12, could have been jailed for up to one year and/or fined on each charge.