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On 7th January 2021, the Drugs & Forensics Publications team had the pleasure of interviewing with scientists from the Health Sciences Authority (HSA). We were warmly received by three scientists: Ms. Zhang Hui Fen Hannah, Ms. Lim Shing Min and Mr. Kua Guo Wei.


Ms. Zhang is a Senior Scientist working in Drug Abuse Testing Unit of the Analytical Toxicology Laboratory (ATL-DAT). She has been working in HSA for around 12 years. Ms. Lim is a Senior Scientist from the Forensic Chemistry and Physics Laboratory (FCPL) and has been working for about 10 years, Mr. Kua is from the DNA Profiling Laboratory (DNAPL) and similarly has been working for about 10 years.

Tell us about your experience testifying in court. How did you prepare? What is the process like before, during and after trial for you as an expert witness?


Hui Fen: DAT is one of the forensic laboratories that requires the scientists to testify in Court frequently. Before we attend the Court trial, we will read up on all the case details and arrange an interview session with the Deputy Public Prosecutor (DPP) and the Investigating Officer (IO). So, during the interview, we will discuss about  the possible points of contention of the case, whether there is Defence Counsel or Expert being engaged for the trial, explain how the analysis are performed in the laboratory and results interpretation, and etc. Other than that, I will also read up the literatures pertaining to the case. For the court trial, I’ll make sure the case notes and other relevant documents and information are well prepared. After the trial, the IO will update us, whether we will be required  in court again or whether the case has concluded.


Shing Min
: For myself, I’ve only been to Court only once. Similar to what Hui fen has shared, generally there will be an interview with the DPP. This is mainly for them to ask any questions they have because of how technical our reports are. Generally, as lawyers, they need to understand what we have done with regard to what we put in our report. We will also check if there are any visual aid they require to help the Judge, the Court and the Defence Counsel understand what we wrote in our report and the conclusions that were made. These are the main preparatory work that we do.


Guo Wei: I think my two colleagues have mentioned most of the things that we go through and experience when we go to Court. For myself, I’ve only been to Court less than 10 times. What I want to add on is that a Court appearance or testimony is usually half an hour or an hour max. The amount of time we put in to prepare for Court trial is usually half a day, to days, or sometimes even weeks, because we’re handling a lot of pieces of evidence. However, when we go to Court, the points of contention are usually about one or two pieces of evidence only. As a forensic scientist, we don’t know which pieces of evidence are the most crucial in the decision-making by the Judge. We are preparing to be questioned for every single piece of evidence that has been examined by the lab, which can take very long. Sometimes when we go to Court, we may think “Hey I’ve prepared so much” but we’re only on the stand for about 15 minutes. Sometimes, not even for that long, because sometimes we’re just asked whether we’ve put up the report and we just say “yes”. Sometimes they just ask, “What’s your name?”. It’s not always that we receive a lot of questions.


Khai: That’s very interesting – only 10 Court appearances despite a long career. This leads nicely to my next question


Since you prepare to be asked about every piece of evidence in a case, can you tell me what was the most interesting piece of evidence you’ve talked about in Court? Or perhaps, about a piece of evidence where, you’re prepared to share it, but didn’t have the opportunity to?


Hui Fen: My laboratory provide testing of controlled drugs in hair and urine samples. We’re not like Guo Wei’s laboratory where they receive many different kinds of exhibits.


Shing Min: In FCPL, we deal with physical evidence and we have various disciplines. So my area of expertise is actually in toolmarks and manufacturing marks. So, the most common type of cases where the DPP calls us would be the narcotics cases where packaging materials are involved and there is a need to examine manufacturing marks of these packaging materials. Actually, I went to two trials. Both trials were for narcotics cases. Quite fortunately, I spent only an hour or so going through my report plus the visual aids, like how manufacturing marks are found, where are they on the materials, my findings and what they mean to the Judge. After the first round of explanation, I looked at the Judge. He seemed like he understood my findings, but of course afterwards came the Defence Counsel for cross-examination. Quite fortunately, they both said that they didn’t have any further questions. I could see the DPP’s face. It was a relief for me because none of them had questions and I was let off the stand. For the other case, I had more questions from the Defence Counsel. In Court, I also had to explain the manufacturing process. I think the case involved envelopes, so I brought envelopes to court to illustrate to the Judge how the manufacturing process went. I had to open up the exhibit to show the Judge and Counsel. They also asked for part of my case notes, asking about what I meant by chemical compositions. Those were my two experiences.


Guo Wei
: Okay, my experience in Court. A few years ago, if you followed the news, there was a murder at Gardens by the Bay. For that case, we did receive quite a few interesting items to analyse because there was no body found. The police went to the scene to collect tonnes of different things ranging from debris, to stones, to leaves, hair and this one particular thing that we found very interesting. They submitted what they thought was human tissue. It was a Sunday, and I was at home. The IO called me and said “Hey, we found something. Can you come pick it up and see if you can find any DNA on it”. So, I went back to the lab along with some of my colleagues immediately. We opened the evidence to take a look and my colleague asked me “What’s this? The IO says it’s human tissue??” Indeed, it actually looked like a longanto me, one that fell from a tree. Obviously, when we examined it, nothing came out of it. Then, we also received some soil, and upon examination, there was worm in it! And obviously, that didn’t yield any results… This is just one of the murder cases we handled. In murder cases, the police may seize tonnes of exhibits because the idea is that you never know what happened. We can’t just focus on one particular cause of death. So, the Police may submit over 50 kinds of evidence. In the end, only one or two may be relevant to the case. Some typical exhibits they submit for murder cases are knives and bloodstains. For obvious reasons, the knife will be one of the more important items. But I’ve also seen cases where they can’t find the murder weapon, so they end up sending things that happened to be at the scene. For example, we’ve received chairs before. Because the police managed to find some bloodstains on the chair, it’s up to us to find out who left the bloodstains. Maybe on the whole chair, there’s only one particular area where the bloodstains are and we need to look out for it. What else… Oh, I can’t remember what case this was for, but we’ve received a cut-out fence before! A fence that was about a 3-by-3 metres in length! I think it was a break in. Other things… For rape cases, a lot of times, they send us the entire bedsheet or mattress where the act happened.


Khai: May I ask, how do you deal with the large exhibits that get sent to you? I know in Chain of Custody that evidence is usually packed in small bags or envelopes or boxes. But what about lager items? How do they get transported?


Guo Wei: The police will package it and wrap it up in paper, like how you’d wrap a present but much bigger. We  do face some challenges in transporting and examining large exhibits in our lab due to space constraints– . The moment we have to examine such items, everything else will be put on hold. So, these were some of the more interesting items I’ve seen in my time at HSA. Before my time, of course, there were other things submitted. I’ve heard of leaves from the forest where supposedly a sexual assault occurred. Oh, there was also a case recently where a baby was abandoned at the rubbish chute in Bedok, so we received items from that scene as well. Although it’s difficult and we put in a lot of effort to examine the evidence we receive, eventually, if we get results and it helps the police in their investigation, we’ll all be very happy.


Do you think there’s anything unique about drug cases as compared to other types of cases?


Hui Fen: What I think is unique is that there are always two scientists involved in every drug consumption case in relation to urine testing. Under the Misuse of Drugs Act (MDA), there is requirement for a subject suspected to have consumed of a controlled drug to provide two bottles of urine specimens to be sent to our laboratory. These two bottles of urine specimens will be analysed by different groups of laboratory officers and scientists. The reports pertaining to the urine specimens are independently issued. So, this is different from the rest of the other forensic laboratories.


Shing Min: Usually in my lab, we’ll usually examine plastic bags, plastic films, straws – these are all common materials used on drug trafficking criminals to sell drugs to buyers. We’ve also had other cases like fibre transfer cases where they want to know whether the tape bundle containing the drugs were in backpacks and belong to the suspect because the suspect can possibly deny that they were aware that the drugs were inside their bag or if they had come into contact with the drug packages. We also get some cases involving urine where we need to the detect the presence of urine. This is because some of the drug offenders refuse to provide any urine samples to the narcotics officers and they end up urinating on their clothing, so we also have to do such examinations. But the bulk of our cases still involve packaging material examination. Generally, for such cases, the analysis required is to associate the possible locations or the link between buyers and traffickers through these packets. It’s possible to say from the packets that they were consecutively manufactured, so these may infer some sort of connection between the trafficker and the buyer. It’s more of if our evidence can prove that the traveller is aware that the drugs were in their suitcase.


Khai: Two years ago, we went to the Home Team Academy to learn about how the police catch these smugglers. One of the officers told us about how such smugglers used the buses coming in from Johor to smuggle drugs.


Have you managed to find fingerprints as you were unwrapping the different layers of drug packages? We learn about this in our modules where small trace evidence gets stuck in the tape between layers that can link suspects to trafficking.


Shing Min: Yes, I’ve encountered a case where I saw fingerprints when examining the exhibits. I saw ridge-like features that looked like fingerprints. Actually, fingerprints are not handled by HSA, so we called in the IO and he brought his colleagues over to take photographs of the ridges. In such cases, we will also try to preserve the ridges, even though they’ve taken the photographs, until we return the exhibit. It’s part of our training to be able to identify other possible types of evidence that may be helpful to the case. We may also suggest other examinations to the IO and see if they require such examinations.


Guo Wei: To link to your question on whether or not you can find fingerprints on the packages, we don’t exactly look for fingerprints. Of course, if we see it, we will inform the police. But we are more looking out for the DNA left behind by the person who handled the drug packets. Usually, they are plastic bags or tape bundles, as Shing Min mentioned. What’s so unique about these tape bundles? Well first of all, they’re very difficult to unravel. I don’t know how long these offenders take to warp these packages, but there are just layers and layers of tape. Electrical tape you can imagine is difficult to unravel.


Khai: Is that the thick black tape?


Guo Wei: Yes, something like that. Then you have to try and obtain DNA from them, and also know which part of the tape is on the inside and outside of the packaging, as this can affect the case at trial. How this is reasoned is that if your DNA is found on the outside and not on the inside, it’s possible than you may have been one of the persons handled the drugs but not necessarily package it.


Khai: Yes, you won’t want to incriminate yourself.


Guo Wei: Yeah. The accused may claim that someone gave them the packet and they passed it off to someone else. They don’t know what’s inside the packet. But if your DNA is found in the interior, the prosecutor can argue that you may have seen what’s inside the packet, so you can’t claim that you didn’t know. That’s one aspect. The other aspect is that we’re dealing with very low-level DNA, we call it touch DNA. People may argue saying that the DNA was transferred to the package, they have no recollection and that they didn’t handle the package, someone else did so my DNA was transferred from that person to the package because they happened to know this other person. So, these are the kinds of questions that may come up at trail. But as forensic scientists cannot comment specifically on how the DNA appeared there because there are tons of possibilities. But whether it’s probable is another story.


Khai: That’s very interesting! Good to hear that everything I’ve learned in class is utilised on the job.


Why is urine the best detector for drugs compared to blood and/or hair? What characteristics of hair and blood that make them weaker exhibits compared to urine?


Hui Fen: I wouldn’t say urine is the best matrix for drug detection. However, I would say  urine is the most common matrix  used to detect recent drug consumption due to its ease of collection, less invasive and it has relatively longer detection time compared to blood. So, for each unique biological sample, they have their pros and cons. It depends on the purpose of the use. For hair, it has the longest detection time and it is commonly used as  a complimentary matrix to drug testing in urine and blood. Why? Because, it has a longer detection time, so it enables us to know the drug abuse history if we conduct a segmental analysis on the hair. Whereas for blood, it has the shortest and fastest detection window, and it is commonly used to determine if the person is under the influence of drugs or alcohol at the point of arrest. So, yeah, it all depends on the purpose. I wouldn’t say that one is better than the other.


What kind of drugs can hair, blood and urine detect?


Hui Fen: For urine, we usually detect the metabolites of the parent drug. In general, after a drug is being consumed, it will metabolise in the body into metabolites. So, in urine, we will detect the metabolites for proof of drug consumption. For hair and blood, we usually detect the parent drug, i.e., the drug that has been consumed.


Can you tell me how accurate these tests that you conduct are? What’s the accuracy so far?


Hui Fen: To confirm a drug presence in a sample, we will conduct two tests; first a screening test, followed by a confirmation test. So, depending on what drugs are to be tested, either an immunoassay or  a high-resolution mass spectrometry test is conducted for the screening test. As for the confirmation test, the test is conducted together with a reference drug standard using an analytical instrument such as a gas or liquid chromatography mass spectrometer. We also have quality controls that are analysed together with the samples to ascertain the quality and accuracy of the test results.  All these methods and instruments that we put into routine use for caseworks are all validated and tested to ensure they are fit for the purpose. Apart from that, our laboratory also participates in international proficiency testing programmes to ensure that our results and tests are accurate and reliable. We are also accredited, meaning to say that our work is recognized by international accreditation bodies.


What are these international accreditation bodies?


Hui Fen: So basically, these are accreditation bodies that forensic laboratories need to go through to get the accreditation for the laboratory’s technical qualifications and competence in conducting forensic testing.


Khai: Okay, so that’s it for the expert witness-type questions. I’ll move on now to questions related to HSA.


What is a day in your life at work like? 

Hui Fen: For me, I will be overseeing the submission and analysis process of urine and hair samples. I’ll make sure that the samples are analysed correctly and when the results are ready, I’ll need to analyse and interpret them and put up a report. So besides doing case work, I also commit my time  in research and development to develop and validate new methodologies for the detection  of new drugs of abuse in hair and urine. I also spend time in answeringqueries that IOs have for me and prepare for upcoming trial, in any.


What are some new methods in drug testing that you’re currently working on?


Hui Fen: Currently, NPS (new psychoactive substances) are the new drugs of abuse which have overtaken Cannabis as the 3rd most commonly abuse drug in Singapore.  With the fast-changing trends of NPS, the laboratory is moving towards using more sophisticated and sensitive instruments such as high-resolution mass spectrometers for drugs detection. This is because some of these NPS are more potent and often present in very small amounts in biological samples, so we need very sensitive instruments to detect them.


Shing Min: Most of my time will be in the lab. Most of the case work will be spent at the microscope because when we examine the packaging materials for example plastic bags, we will do it under the microscope. This process cannot be automated so more time will be spent there. We do get quite a lot of bags per case, and by a lot it’s like in the hundreds, so much of our time will be spent using the microscope. So other than case work, we also do give talks to like agencies or schools, our client stakeholders to help them to understand the kind of work that we do at HSA and how our work can assist them in their cases and investigations. We may also be required to do validations for probably new packaging materials that we encounter, to look at what the manufacturing process is like and what type of characteristics can be used to distinguish these packaging materials. Sometimes we do get things like Styrofoam boxes. Recently we had cigarette boxes, tobacco boxes, even courier delivery packaging. So, all these are things that traffickers might use to pack drugs, so when we encounter such evidence, we first need to understand how it is being made, what characteristics are being imparted on them, so that when rendering a conclusion is can be as accurate as possible. So, that’s mainly what we do on a day-to-day.

Khai: I didn’t know that as a scientist you also do outreach. I thought that was mostly a different team in HSA. That’s interesting! Do you work with the Central Narcotics Bureau (CNB)?

Shing Min
: Yes, they have their training sessions quite frequently so our forensic scientists will go down to share about the evidence that we most commonly encounter in drug scenes. Because their scenes are different from the murder and house break-in scenes. The type of evidence found is also different. So yearly we do have colleagues going down. During such sessions it’s good that we also share on the other areas of our work that we have in FCPL so should they have any enquiries, they can ask us directly. We also do document examinations. Sometimes these are encountered in drug cases where we have the handwriting of the accused writing down the transactions of the drugs. All these will require our examination of the handwriting.


Guo Wei: Okay, for my day at the lab… Actually, it’s not much different from what Hui Fen and Shing Min have mentioned. The same things: examining evidence, have meetings, giving talks to the stakeholders. Maybe a more personal take on how my day usually looks like. So, I usually reach work in the morning. Then, because we receive tons of exhibits, and for each exhibit we need to write a report, every day I will be writing reports. I’ll also be checking reports from others because before we get to issue a report, there must be another person checking the reports. We also have to keep reviewing our protocols in the lab, ensuring that things don’t go wrong, maintaining the quality of our testing. And of course, the criminals also have access to the Internet and Google, so they keep improving their “techniques” to commit crimes. At the same time, our colleagues conduct research and development to keep abreast of all the newest technologies that are out there to make sure that whatever the criminal does, we can do it better. Yeah, they try to hide, we try to find them. So, R&D is part of our work that we have to keep doing. At the same time, we also have to juggle with the daily casework that we’re getting from all the police land division that we have. Sometimes, we also receive test requests from the SAF. You know Tekong is not all paradise. Crimes do happen at Tekong and we are tasked to help them as well.


Khai: Besides the SAF, do you get requests from private organizations? If I’m not mistaken, I read that the HSA does do that.


Guo Wei: No, for us at the DNAPL, we don’t receive requests from commercial organizations. We do receive cases for example, when a girl undergoes abortion and she’s underaged – well this is also a crime – then we will try to find who the father is. I think that’s about it that I can think of.


What kind of qualities are you looking for in people who want to go into your line of work? What traits must they have to excel and be able to do the kind of things you do?


Hui Fen:  For my laboratory, we need someone that has an analytical mindset and meticulous, diligent and most important of all, to have the confidence to give testimony in court.


Khai: Is testifying very difficult, like do you personally struggle when you testified for the first time?


Hui Fen: Well, I guess more or less, at my very first time, I was be a bit nervous, but my laboratory has trained me well in giving testimony in court. So, even though There may be points of contention, but I have prepared and discussed with the prosecutors and IOs for the trial.


Khai: Who does the training? That’s interesting. Is it other senior scientists or external people?


Hui Fen: Yes, training is done by our senior scientists or Directors. Other than that, we also attend trainings by the Attorney General’s Chambers (AGC).


Shing Min: Regarding qualities, I think one that’s very important to us is being meticulous. A lot of our evidence, we do trace evidence as well, so we require our scientists or lab officers, when entering a scene, to be able to identify the different kinds of evidence to provide suggestions regarding collection of all of these. Trace evidence can’t be seen, so you require an eye for details and the bulk of our work in most disciplines in my laboratory requires working under microscope. Generally during the interview, we will let interviewees have a practical test where they will be asked to operate a microscope. They will be given material that they have to see under the microscope and do some cross sectioning. So, their hands, their technique, they must be comfortable working with the microscope for long hours. It requires a lot of patience. I believe that we provide the training, so, as long as the person is willing to learn, we will be willing to teach. They must also have the interest in our line of work. We will also ask if they are afraid of blood, whether they are okay with seeing bodies and have issues or concerns. These are all the additional questions we will ask them because it’s part and parcel of our work.  Because crime can happen at any time. We can’t say we can only go down to crime scenes during office hours.


Khai: That’s interesting because I always thought the SPF has their own forensics team that goes down to crime scenes.


Shing Min: Yes, usually in most cases, they will be the one collecting the evidence. If they require our assistance, we will go down. But most of the cases are handled by them. If they need advice, then we will go down.


Khai: Does that happen often? When do they specifically ask for HSA to go down to crime scenes?


Shing Min: Generally, probably a few hours after the crime happened? After they’ve looked at the scene and they need advice, they’ll give us a call. We get calls probably around once a month or so. Not every crime requires us to come down to a scene. Some questions we get asked are how to collect a certain kind of evidence, so if we can offer the advice over the phone, we don’t have to go down.

: I see, so it’s like you’re always on call.


Shing Min: Yeah, we do have an office phone they can call if they need us to go down to a scene. It’s an office number.


Guo Wei: For us, it’s about the same. What we are looking for quite general for the forensic science field. You have to be meticulous, have an eye for detail. You need to be able to communicate both within your team and outside your team, for example, communication to the police. You must also be able to communicate your results well to the Judge. This is not only just in technical terms. Because judges are usually laymen, you’ll need to explain technical terms in simple ways so that everyone can understand your report. I think that is a very important skill to have because a lot of times as a science-trained person, you are stuck with jargons. Sometimes, certain things are very hard to explain in a simplistic way, but that’s a skill that you need to have because if you only stick to the technical terms, you will never get your message across. Then what will happen is that either they will accept your evidence since they don’t understand, or, since they don’t understand, they throw out your evidence. So is very important to have good communication on your part. Like what Shing Min mentioned, the evidence that we receive, especially for murder cases can be bloody items, so a person working in our lab, has to be able to withstand blood, We have received a fetus. You have to maintain your posture and know what you need to do. You cannot be emotional. Also, what you need is sort of a criminal mind I guess, because you need to know how to commit a certain crime so that you can imagine where the criminal has touched the things that you’re looking for. That is where you may be able to find the DNA of the criminal. So, imagine someone broke into a house, so you must think “Where could he have possibly entered the house” and this is where you determine the area you want to examine. I think Hui Fen and Shing Min have mentioned all the other traits.


On top of what you’ve already mentioned, do you have any other advice for graduates looking to work at HSA?


Guo Wei: I think in Singapore we don’t really have a major in Forensic Science. I’m a graduate in Biological Sciences. So, that is sort of sufficient to join HSA in the DNAPL. Of course, for other labs, Biology is not relevant. You may need other specializations. I would say that this is an interesting field, it’s very niche. As a Biology graduate, what I see from my ex-classmates is that they either go into research at labs or go into teaching. So, forensic science is different from the rest.


Hui Fen: I guess for my laboratory, it’s the same. If you’re not afraid of handling biological samples, testifying in court and you want a challenging career, you can join us.


Shing Min: I think for graduates, this job is very unique, very meaningful and very important, the work we do here. It’s really a fulfilling career because for the past 10 years I’ve been here, every year, I learn new things which I find very rewarding. It’s not just technical knowledge. Technical knowledge, like Hui Fen said, is always changing and we have to keep up, so it’s not very routine. Although the examination part is routine, but we always have to keep up with the ever-changing trends, the different kinds of evidence that can come in because they can come in any form, anything under the sun, like the fence Guo Wei mentioned. Anything is possible. So, it’s a very rewarding experience, both at a technical level and a personal development level. It’s just rewarding overall.


This concludes the interview. I would like to take this chance to thank Ms. Pauline, Ms. HuiFen, Ms. Shing Min, Mr. Guo Wei and Dr Syn for taking the time to speak with CJC-F.

*The views and opinions expressed in this article do not constitute legal advice and solely belong to the author and do not reflect the opinions and beliefs of the NUS Criminal Justice Club or its affiliates.

Authors’ Biography

Muhammad Khairul Fikri is a Year 3 undergraduate from the Faculty of Arts and Social Sciences. Khai is one of the Project Managers of “Drugs & Forensics”. He is pursuing a Major in Geography and two Minors; Forensic Science and Geographical Information Systems. He is interested in the applications of technology, particularly geospatial technologies, in forensic science and crime scene investigations.