That question has lurked beneath many a discussion about the terrorist's stunning getaway on Feb 27.

It came to the fore in Parliament yesterday when Prime Minister Lee Hsien Loong responded to a question from opposition Non-Constituency MP Sylvia Lim over government responsibility for the escape.

Mr Lee made his stand clear: that the Government accepts responsibility for the mistake, as expressed in the DPM's apology to Parliament the day after.

Beyond that, the question of individual ministerial culpability was one for the Prime Minister to determine.

Said PM Lee: 'I will ask the same questions of the minister: How is he involved in the matter? Has he been incompetent or negligent? Most serious of all, is there a question of integrity? If so, he has to go, even if the actual incident is minor.

'I will also ask: Is the minister able to put things right or does the situation call for a new pair of hands not encumbered by what went before to take charge and make a fresh start? Of course, the Prime Minister himself is accountable too, to Parliament and ultimately to the electorate.

'However, we should not encourage a culture where officials and ministers resign whenever something goes wrong on their watch, regardless of whether or not they are actually to blame. That would be the easy way out. It may temporarily appease an angry public but it will not fundamentally solve the problem.'

So, with that framework in mind: Was the escape in this case the result of any personal wrongdoing on the minister's part? Clearly not.

Was it the result of an erroneous policy he made? No.

Was it the result of mistakes committed by others, mistakes that he knew about? No.

The escape took place because of operational lapses in an agency under his ministry.

As minister, he has to accept responsibility, which indeed Mr Wong has with his swift apology and in facing Parliament for three hours on Monday to give a comprehensive accounting of the event.

Fatigue etched on his face, Mr Wong sat impassive and sober when PM Lee stood in front of MPs to explain why he retained full confidence in his deputy.

I, too, do not see the need for the minister to resign, nor would it be wise of the PM to remove a steady minister at a key portfolio.

Anonymous bloggers and grandstanding kopitiam rabble rousers aside, I am doubtful if many right-thinking Singaporeans seriously think Mr Wong should resign over one lapse in one of his agencies.

There is a difference between comments made to ventilate emotions and hard-headed comments meant to be acted upon. The 'heads should roll' and 'minister must go' comments belonged more to the former than to the latter category.

But they gained traction in the cocktail and kopitiam circuit because of a perception that the Government was not accepting responsibility to a sufficient degree.

From the Government's perspective, the minister's apology was made on behalf of the Government and was swift and full.

But citizens may not see it that way. Some feel that the words in the apology side-stepped responsibility.

Now, this is a matter of opinion. But if you split hairs, you can argue that 'I'm sorry that it happened' is different from saying 'We made a mistake and I'm sorry for the mistake'.

The former expresses regret at an incident happening, a view no doubt shared by most Singaporeans, who were also sorry that Mas Selamat escaped. The latter accepts institutional and personal responsibility.

This is a small detail, but nuances matter in political communication.

The distinction may have caused the perception that the Government was not facing up to its responsibility to a sufficient degree.

PM Lee, in expending political capital built up since he became premier in 2004, has made clear that the Government accepts responsibility and that he retains full confidence in DPM Wong. This, together with Mr Wong's detailed account of what happened, should go some way towards mollifying those who thought the Government was ducking responsibility.

But it will not satisfy them completely. This is because many people tend to understand the notion of accepting responsibility for mistakes in only one way: that heads must roll.

However, there are different degrees of sanction for errors made by people in an organisation: from internal verbal censure to public censure, written censure or financial penalties.

Dismissal is the most extreme sanction and is not one to be taken lightly, as it may serve the organisation no good.

In the Mas Selamat case, those who think that heads should roll will not be satisfied that those removed from their posts were the Whitley Road Detention Centre's staff.

As questions from Ms Lim and her Workers' Party colleague Low Thia Khiang alluded to yesterday, this left unanswered the issue of institutional accountability and the Ministry of Home Affairs' (MHA) oversight role over the Internal Security Department (ISD).

The minister himself has accepted responsibility in giving a detailed accounting and an apology.

Singaporeans hold the Government to very high standards of accountability.

PM Lee's repeated calls to avoid a witch-hunt are salutary.

But Singaporeans want to know that some form of sanction extends beyond the detention centre to those up the line, and that the buck did not stop at Whitley Road - but went beyond that to the Novena area where the ISD and the MHA headquarters are sited.

muihoong@sph.com.sg