SINGAPORE - A disgruntled Immigration and Checkpoints Authority (ICA) assistant superintendent decided to fix his former supervisor by sending an e-mail falsely stating that the officer could have taken photos of another man in a public toilet.

As a result of his actions, Thomas Foo Jian Yao's victim - Superintendent Lee Teck Seng, 46 - was subjected to an investigation, during which the authorities raided his office and home, impounded his passport and seized his personal mobile phone.

Foo, 29, pleaded guilty in a district court on Monday (March 16) to one count of giving false information to a public servant. Court documents did not state if he is still an ICA officer.

Deputy Public Prosecutor Emily Koh said Foo was upset with Supt Lee, who was his supervisor from October 2016 to October 2018. He felt that Supt Lee had discredited him in front of his new supervisor, and should have raised the matters, which were not disclosed in court documents, with him instead.

Foo carried out his plan while on holiday in Phuket, Thailand.

After buying a mobile phone and SIM card, he created an e-mail account with which he sent the message containing the false accusation at around 2.40am on Aug 8 last year.

Posing as a counsellor called Joseph, he sent the e-mail to nine people, including ICA's Deputy Commissioner Hsu Sin Yun.

Foo claimed that Supt Lee could have used a mobile phone to snap photos in a public toilet at Seah Im Food Centre near Telok Blangah Road.

When Mr Hsu received the e-mail, he forwarded it to the director of ICA's operations division. Another ICA officer then lodged a police report at around 4.30pm that day.

DPP Koh said that as a result of Foo's actions, Supt Lee was "unnecessarily subjected" to investigations.

On Aug 9 last year, police sent a message to the e-mail address which Foo had created in Thailand, asking for the sender's help in investigations.

Foo was in Century Square shopping mall in Tampines when he used the public Wi-Fi signal to reply to the police on Aug 21, last year, claiming that he did not have time to go down for an interview.

His whereabouts, however, were captured on devices such as closed-circuit television (CCTV) cameras that day and the police were able to identify Foo.

On Sept 3 last year, he finally came clean and admitted to the police that he had made the false accusation against Supt Lee. Foo will be sentenced on April 16.

For giving false information to a public servant, he can be jailed for up to a year and fined up to $5,000.