SINGAPORE: As the novel coronavirus spreads in Singapore, a kind of puzzle began to emerge. Not on the frontline where doctors and scientists rush to find a vaccine, but behind the scenes where police officers race to find the cause of a “crime”.

On Feb 12, two employees of the Grace Assembly of God church were identified as confirmed cases of COVID-19. By the end of the month, the number of cases linked to this cluster had swelled to 17.

Authorities scrambled to determine how the cluster was infected. Knowing the source would mean greater assurance that the cluster was under control, and that the virus was no longer spreading in the community.

The Health Ministry (MOH) had started contact tracing as soon as the first case in the cluster was confirmed. But soon it became clear that more help was needed. This is where the Singapore Police Force’s Criminal Investigation Department (CID) comes in, as the department’s officers described their roles to reporters on Tuesday (Feb 3).

The police holds a daily video conference with the Health Ministry to share updates. (Photo: Aqil Haziq Mahmud)

The CID has been roped in to help with contact tracing because of its investigative expertise: Using data analytics to sieve large amounts of information, the ability to trawl through closed circuit television camera (CCTV) footage, and even knowing the right questions to ask during interviews.

On any given day, an average of up to 50 police officers work on contact tracing. Police say this resource-intensive operation can be quickly scaled up to involve 100 officers, when more people need to be tracked down and interviewed.

READ: Chinese New Year gathering identified as missing link between COVID-19 church clusters

This is helpful when authorities try to crack particularly tricky COVID-19 cases, like those that involve close contacts whose identities are not known in the first instance.

After all, the CID had helped determine the source of the Life Church and Missions Singapore cluster – a couple from Wuhan who had the disease had attended a service there.

In the Grace Assembly of God cluster, the links were murkier. The CID branch helping with contact tracing – split into teams of interviewees and analysts – had focused on Case 48, the 34-year-old man identified as the first confirmed case linked to the cluster.

READ: ‘Painstaking’ contact tracing work by SPF led to discovery of possible cluster at Paya Lebar church: Shanmugam

After MOH comes up with an activity log – close contacts, places visited – of a confirmed case, the CID interview team follows up with the individual and his close contacts to fill in the gaps.

This involves speaking to them multiple times over the phone, and sometimes even while wearing protective gear in the wards of hospitals and the National Centre for Infectious Diseases (NCID).

New information is fed to the analysis team, which then uses analytics software like word clouds and location maps to sieve out trends from chunks of data and come up with hypotheses. It is then back to the interview team to verify these hypotheses.

READ: 3 new cases of COVID-19 in Singapore, including DBS employee, 2 church employees

For many days the back-and-forth with Case 48 yielded no definitive answer. “There was a lot of trial-and-error in the whole process,” said analysis team member He Minghui, 37, who also works as an intel analyst for the police.

But this turned out to be a red herring.


The CID switched gears and turned its attention to Case 66, another confirmed case in the cluster whose symptoms had developed earlier than the rest. The 28-year-old man’s activity log indicated that he had attended a Chinese New Year gathering at Mei Hwan Drive on Jan 25.

This quickly piqued the interest of interview team member Assistant Superintendent of Police (ASP) Johnny Lim, 44. For a start, these gatherings could have involved close contact and the sharing of food, raising the risk of infection. Details about the gathering were scarce too.

READ: 9 new COVID-19 cases in Singapore, including 6 linked to Grace Assembly of God cluster

This is the kind of “instinct” that police officers have honed from their years on the job, and has proved useful during contact tracing, said ASP Lim, who investigates organised crime at the CID.

“It’s like crime solving,” he added. “More or less, it’s similar kind of skills required – piecing information from different people and different places together.”

READ: Grace Assembly of God COVID-19 cluster: How it unfolded

ASP Lim reached out to Case 66 for a full list of attendees, carefully jogging his memory as the gathering took place some time ago. There were more than 30 names. He called up most of them, asking questions like what time they were there, how they got there and who they were with. Again, he kept the questions to a minimum so as not to stress them out.

At the same time, the analysis team ran the names of those who had attended the Chinese New Year gathering through its database. Two names stood out – a couple who had attended the same Life Church service as the couple from Wuhan, based on the church’s records. This was the eureka moment everyone had been waiting for.

“There is actually a lot of effort put into the backward tracing part,” Ms He said. “There were many hypotheses put out, but we found this was the most solid one that could possibly explain the link between the clusters.”

READ: 3 new COVID-19 cases in Singapore; 5 more discharged, including Chinese national who was first confirmed patient

ASP Lim reached out to the couple but found out that they were well. The woman was never hospitalised for COVID-19, and the man was only identified as a confirmed case on Feb 19 as Case 83, weeks after the gathering, and had been discharged.

However, ASP Lim was undeterred as this would still mean making progress by ruling out another hypothesis. “It’s not a dead end,” he said. “This information is crucial for us; it still leads somewhere.”

Still, records showed that the woman had gone to Sengkang General Hospital the day after the gathering with symptoms consistent with COVID-19. The man had also been unwell towards the end of January, and repeatedly sought treatment at a GP clinic.

MOH arranged for them to be tested at the NCID, and serological tests – which look for antibodies in blood samples to determine infection even after recovery – subsequently confirmed they had earlier been infected with COVID-19.

police church clusters johnny minghui

Assistant Superintendent of Police Johnny Lim (left) and Ms He Minghui. (Photo: Aqil Haziq Mahmud)

As a result, the woman was designated Case 91, the Chinese New Year gathering identified as the missing link between the two church clusters, and the CID’s work vindicated.

CID officers said this was one of their biggest contact tracing success stories to date, especially as the branch managed to make initial contact with Case 66 and eventually Case 91 all within a day.

“This infection is like an invisible criminal; we don’t know where and when it has happened,” Ms He said. “It is unlike an actual crime, when we know there’s a victim and culprit.”


It’s harder to find this “criminal” considering these officers do contact tracing on top of their normal duties. At least four days a week, ASP Lim works in rotating 12-hour shifts that usually end at 10pm, comprising many hours on the phone and “running” to different places for interviews.

“My regular work has to be on hold until this is done,” he said, calling it “national service”.

READ: Not ‘enough information’ to suspect a COVID-19 super spreader in Grace Assembly of God cluster: MOH

Of course there are challenges. ASP Lim said people have doubted if he was really from the police after he identified himself on the phone. This slows him down in a process where speed is critical to ringfence the virus spread.

Being wary of officials asking for personal information over the phone isn’t necessarily a bad thing, however, and police have urged the public to authenticate officers’ identities by calling their police station.

In ASP Lim’s case, one person who attended the Chinese New Year gathering had questioned his identity even after calling MOH’s hotline. In situations like these, ASP Lim would usually try to verify himself to family members and get them to convince the skeptic.

“We will try to convince them as to who we are and that we are really doing legit business here,” he said, adding that he would pass them the CID hotline so colleagues could officially transfer the call to him.

police church clusters daily conference

Officers say they are working harder and putting in longer hours to balance core duties with contact tracing, but acknowledge the importance of this work. (Photo: Aqil Haziq Mahmud)

The other difficulty is teasing the details out of people.

“Patients repeat the same story a few times to different people,” ASP Lim said. “So when my turn comes, they can get quite impatient as they have to repeat it.” But he said people are “generally very understanding” after he explains the purpose of his job.

Closer to home, ASP Lim said his wife is supportive of what he’s doing despite the long hours, adding that she helps to manage the household chores. His three children aged 12, 10 and seven are too young to understand, he said.

“They know this virus from the television, so I just tell them that papa is going to look for the virus,” he added with a laugh.


Beyond looking back in time to find the source of infection, police officers deployed to what is called the field team are also tasked with forward contact tracing, like tracking down the people who had sat in the same taxi or cinema as someone with COVID-19.

This involves the gruelling task of reviewing hours of CCTV footage, conducting ground enquiries at different locations and identifying people simply based on how they walk or what they wear.

READ: 7 new coronavirus cases in Singapore, including taxi and private-hire drivers

Senior Staff Sergeant (SSS) Mohamad Shapie Saleh, 38, was involved in tracking down passengers who took the taxi of Case 35, a 64-year-old man who worked as a taxi driver.

As many of the passengers paid in cash, there were no official personal details. SSS Shapie, who works in the Crime Strike Force at the Bedok South Neighbourhood Police Centre, recalls being activated for an entire evening for this case.

He was asked to find four passengers based only on their attire and a generic pick-up point, in a task akin to finding a needle in a haystack.

“Based on the attire, we try to trawl all the CCTVs within the area to see if there’s a person matching this attire,” SSS Shapie said, stressing that the smallest details matter.

police church clusters interview

The field team helps to trace close contacts whom MOH is unable to reach or locate for quarantine orders to be served. (Photo: Singapore Police Force)

SSS Shapie was told that a man wearing a white top and black pants had boarded Case 35’s specific cab on Chai Chee Road. The mission was to find out where the man lived and confirm that he had indeed taken the taxi.

Like a game of Where’s Wally, SSS Shapie took some three hours to sift through footage from 40 police cameras at five HDB blocks in the vicinity. If the man disappeared from the footage, he’d have to go back and possibly look through cameras at nearby shops.

SSS Shapie managed to trace the man to a lift lobby at an HDB block, and finally from the camera in the lift, got a clear view of his face. The officer noted the floor he got out at and knocked on the doors of every unit there, describing how he looked like and asking if he lived there.

He found the man, confirmed that he had taken the taxi, and said the MOH would be in touch. Again, some of these passengers had trouble recalling if they had taken the cab as it happened weeks ago. They also doubted that police officers were helping out with contact tracing.

“They’re quite surprised and would not believe that they were being traced,” he said. “At the same time, they are also worried that they might have the virus.”


The process is a little different for Sergeant (SGT) Loh Seng Hong, 33, who was asked to track down two individuals who had sat near Case 48 in a shopping mall cinema in Orchard.

SGT Loh, who works in the Crime Strike Force at the Orchard Neighbourhood Police Centre, had already received from cinema staff CCTV footage showing their faces, based on ticket details and cameras at the booking counters.

police church clusters ground enquiries

Senior Staff Sergeant Mohamad Shapie Saleh (left) and Sergeant Loh Seng Hong (middle) conducting ground enquiries. (Photo: Singapore Police Force)

But SGT Loh did his homework and discovered that the footage displayed a time code that was faster by five minutes, and hence confirmed he had the wrong people. He looked through the footage again to get the right faces, then it was more of the same.

“Orchard is a shopping belt, so we trawled through mall CCTVs,” he said. “Some of them after the show, they don’t go back straight. So we needed to follow their movement when they went for dinner and stuff.”

It sounds easy because SGT Loh said he’s been in the Orchard strike force for five years. “We’ve looked through a lot of CCTVs,” he explained. “We have picked up the skills. Even by the walking patterns of individuals, we are able to identify them.”

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