There are too many questions about how such a security breach could have occurred, raising concerns regarding the competence and alertness of the officers involved.
These queries need to be answered quickly to reassure Singaporeans that the authorities are on top of their game.
Questions: How did the woman drive past immigration control in such a brazen manner without being detected?
It was reported that she tailed the car in front of her and went past the vehicle barrier without stopping for the usual immigration checks. Why did the officer manning the booth not notice her car when it went past? When did he notice and at which point was the alarm raised? If it took a full two minutes for the alarm to be raised, as was reported, why did it take so long?
After clearing immigration, vehicles proceed to the Customs checkpoint where officers check for contraband and goods to be declared.
This is some distance away, and if the officers there had been alerted in time, the offender might have been apprehended there. Were they alerted, and when exactly? What is the procedure for such alerts to be passed from the Immigration to the Customs checkpoint?
It is cold comfort to know that the woman had apparently sailed through Malaysian immigration checks as well, as her passport was not found on her when she was arrested.
Then, there is another set of troubling questions about how she was able to go undetected for three days.
Questions: What exactly was the nature of the alert raised by the immigration department to the police and security forces in Singapore after she left Woodlands?
Was it a high priority warning? What is the procedure when such alerts are raised?
For example, is every police officer asked to be on the lookout for the driver and the vehicle? This question is pertinent because, on the third day of her illegal stay here, the woman tailed a taxi and the cabby called the police to report her suspicious behaviour.
He was told to drive to the police complex in Cantonment Road, which he duly did, with the Malaysian driver hot on his heels.
You would have thought that was the perfect trap to lay. Mission accomplished?
Alas, when they reached the station, she was apparently questioned about her behaviour but she refused to answer and promptly drove away.
Did the police officer questioning her know she was a wanted immigration offender? If not, why?
The woman has been charged and the answers to some of these questions might be clearer when the case goes to court.
No one wants to be unduly critical of the men in blue because the job they do is a difficult one that sometimes puts their lives in danger.
Singaporeans know that the country's reputation as a peaceful and secure place is founded on the work they do and are grateful for it.
But it is a job that requires constant alertness and vigilance all round.
When so many lapses take place one after another, involving the Immigration and Checkpoints Authority of Singapore (ICA) and the police, it calls into question not just the competence and attentiveness of individual officers involved but also the integrity of the system as a whole.
Indeed, the Government knows the seriousness of this breach and it could not have expressed its displeasure more clearly than when Deputy Prime Minister and Home Affairs Minister Teo Chee Hean made public his comments:
"I have expressed my deep dissatisfaction to the Commissioner of ICA and the Commissioner of Police over the breach at Woodlands Checkpoint and the subsequent response actions. This case should have been prevented and dealt with more urgently and decisively as it could have resulted in more serious consequences than what occurred."
His anger wasn't unexpected because this wasn't a case of someone trying to sneak in stealthily in the dead of night but in broad daylight and under the noses of officers responsible for preventing such incidents.
If the offender had been, say, a terrorist out to create mischief, and not someone with alleged mental problems and who was behaving oddly, the consequences could have been very serious.
After the attack on the United States in 2001, and when Jemaah Islamiah terrorist cells were discovered here, the public was assured that the authorities were doing everything in their power to prevent an attack here.
Numerous arrests have been made over the years and persons detained under the Internal Security Act.
Singaporeans slept peacefully knowing the country's security forces appeared on top of the situation.
But the Woodlands breach shows how true the old adage is, that the system is only as strong as its weakest link.
Is the weakness, though, with the foot soldiers manning the booths at Woodlands and the police station at Cantonment? Or are there wider issues that need to be addressed by senior management?
For example, are officers trained well enough to respond to these incidents? What has been done to make sure their attention levels do not suffer as a result of fatigue or long hours of repetitive work?
Are the standard operating procedures (SOPs) on sending out alerts and disseminating information islandwide adequate and effective?
These issues are relevant especially after the Little India riot, when questions were also raised over whether the police responded fast enough to contain the situation.
One other area that needs to be addressed is the visible lack of enforcement officers on the ground - from Traffic Police to police patrol cars to litter wardens.
One online commentator wrote: "In the past, when I drove along the expressways, I (would) see traffic police in a BMW or on a patrol bike. Nowadays, I hardly see any."
Many have made similar observations.
It is obviously costly to have officers everywhere, and it might not be efficient to do so, beyond a certain number.
But one consequence of having too few boots on the ground is not only that people get away with offences but that enforcement officers become overworked, and their vigilance levels drop.
After the Woodlands fiasco, security was apparently tightened at the Causeway making it a nightmare for motorists driving into Singapore, with some reports citing delays of up to three hours.
Hopefully, this isn't the only way to do the checks properly.
There must be better, more effective, methods that do not create so much trouble for the public.
Whatever the reasons behind the extraordinary breach at Woodlands, the authorities need to react and respond fast.
Singapore's security depends on it.