For having sex with his underage student, the former head of character and citizenship at a secondary school was jailed for four years and nine months last Monday.
The case drew widespread attention, and the irony of the teacher's position escaped no one.
In response, the Education Ministry has pledged to be more vigilant against such cases, on top of its already "stringent" selection and screening regime.
The ministry already holds regular conversations with its teachers on the Code of Professional Conduct for Educators, a spokesman told The Sunday Times.
"Despite our best efforts, there have been educators who have fallen short of the expected standards. We take a serious view of each case - each is one case too many.
"To uphold the good name of the profession and to safeguard the well-being of our students, we will work with schools to step up vigilance," she added, without providing further details.
Chairman of the Government Parliamentary Committee for Education Lim Biow Chuan wants to know what else the ministry is doing. He has filed a parliamentary question - to be addressed in tomorrow's session - on its plans to protect students from "sexual predators".
In the latest case involving the 33-year-old teacher and his student, then 15, Deputy Public Prosecutor Kavita Uthrapathy had urged the court to pass a stiff sentence.
She noted a "worrying trend" of cases involving teachers and their students - there were five convictions last year.
Since February 2008 - when stricter laws were enacted to protect minors from sexual abuse (see box) - there have been at least 14 cases reported in the press of teachers having relationships with students under the age of 16.
Of these, 11 fell under Section 376A which criminalises "sexual penetration of minors". The offenders were sentenced to between 10 months and 10 years behind bars. The other three involved sexual exploitation, or outrage of modesty.
The figure may be minuscule, considering the 33,000-strong teaching profession, but each time such a crime surfaces, it sends shockwaves across the country.
In the latest case, the teacher and his student grew close after an overseas school trip in 2012. She began confiding in him about her family, and struggles in her studies.
Before long, increasingly personal messages were being exchanged on WhatsApp and Facebook. He told her to toss a coin to decide whether to start a physical relationship with him.
The court heard that they had sex eight times - often unprotected - right up to two weeks before his marriage. The girl was so depressed by the marriage that she contemplated suicide.
In such cases, offenders usually cannot be named due to a gag order to protect the identity of the victims. But they do not fit a particular profile, and can be man or woman, young or old, married or single, and of any race.
While some shower their students with gifts - Calvin Klein perfume in one case and a copy of the book Eat, Play, Love in another - others leverage on text messaging and social media platforms to get closer to their students.
With so few of them around, and no particular "type" to look out for, there is no easy way to weed out potential offenders.
The spike in cases in recent years could be because there are more opportunities for social interactions between teachers and students.
"Many teachers prefer to be seen as friends to their students, and not just as teachers," noted Mr Lim.
And sometimes, they cross the line.
Teachers - with the trust placed in them and their authority over students - must be the ones who discern right from wrong. But they are not infallible, psychiatrists said.
Dr Ken Ung, a consultant psychiatrist at Adam Road Medical Centre, said: "Teachers are also human beings with emotions. They know the act is wrong but when feelings and emotions come into play, logic and reasoning take a back seat."
Such relationships are also difficult to detect or trace - until they go awry, or parents notice something amiss and raise the alarm - because both parties know it is wrong and it is in their interest, at least at first, to keep it a secret.
Said Dr Ung: "Often both are getting something out of the relationship and it is not in their interest to end it."
Such cases tend to arise due to stress, or a lack of a loving figure at home, he added.
"This could be the nice distraction, the powerful thing they turn to for solace and comfort from the general unhappiness."
Parents play an important role in curbing such cases, said Mr Lim, as they "know the emotional needs of their children best".
They should keep an eye out, keep the lines of communication open, but not be overly concerned.
Dr Ung, who has a son in secondary school, is not particularly worried. He said: "Out of so many thousands of pupils and teachers, the number of (such) cases can be counted on one hand every year.
"As an analogy, do I get worried every time I fly? No. Plane crashes are not common at all."