Update March 8, 2018: A 21-year-old man has been nabbed for causing public nuisance, the police said in a statement.
Officers from Jurong Police Division arrested the suspect on Wednesday (March 7) and seized a laptop, a mobile phone, as well as two pinhole cameras.
Preliminary investigations revealed that the man is involved in other similar cases.
If found guilty, the suspect may face a fine of up to $1,000. A person convicted of insulting the modesty of a woman will face a jail term of up to a year, or a fine, or both.
A pinhole camera was found in a handicapped toilet in Nanyang Technological University (NTU) on Mar 1.
The police said that they received "a call for assistance on a case of insulting the modesty of women in Nanyang Drive" at 5.03pm on Thursday (Mar 1), reports The Straits Times.
According to Lianhe Wanbao, the camera was supposedly hidden in a plastic hook that was mounted on the side of the door facing the toilet bowl.
It is understood that the camera was found by a female printing service contractor.
Inside the camera, an SD memory card was found but it is unclear if any videos or photos were inside.
A cleaner at the school told Wanbao that a woman rushed up to him on Thursday saying that someone had installed a pinhole camera in the toilet.
She had reportedly noticed the hook on the door of the toilet, which had not been there before.
She also noted that the hook, which had a freshener pack hanging on it, was placed in a relatively low position, just above the air vents on the door.
She said that it was positioned at the same level as the toilet bowl.
Feeling it was unusual and after some checking, she asked for someone to call the police.
Police investigations are ongoing.