Skip main navigation
We use cookies to give you a better experience, if that’s ok you can close this message and carry on browsing. For more info read our cookies policy.
We use cookies to give you a better experience. Carry on browsing if you're happy with this, or read our cookies policy for more information.
Photo of Dr Penny Haddrill

Ask Penny

Please post your questions for this week in the comments section.

Penny will select the most liked/interesting questions and publish her response to these on this step by Wednesday of Week 6.

Please ‘like’ questions posted by other learners if you are also interested in having these answered.

Firstly, thank you very much for all your excellent questions and comments again this week, I hope you are enjoying the final week of the course, bringing together all of the scientific evidence we have looked at as the case has unfolded. In case anyone hasn’t yet found the answers to the ‘Ask Penny’ questions from Week 3, you can access these on the ‘Ask Penny’ article in step 3.15.

Given that last week was looking at the analysis of illicit substances, there were quite a few questions related to drug analysis. Wendy O’Brien asked a question about the types of analysis that pharmaceutical companies and drugs manufacturers do, which unfortunately is outside my area of expertise, so if anyone knows the answer to this then please do submit an answer below Wendy’s question. Ruth Baker and Doug Karo also submitted various questions about drugs, including synthesis of new drugs, keeping up with definitions of these new drugs, when drugs seizures would be profiled and the purity determined, and issues associated with prescription drugs.

In terms of the production of news drugs and how law enforcement keep up with this, a major issue in forensic drugs analysis in recent years has been the analysis of ‘new psychoactive substances’, previously known as ‘legal highs’. These terms refer to chemicals that used to be legal, but produced similar effects to illegal drugs such as cannabis, amphetamines and cocaine. These were produced with the aim of avoiding the laws controlling the use of illicit substances, which in the UK is the Misuse of Drugs Act (1971). For example, synthetic cannabinoids are a group of chemical compounds that mimic the effects of cannabis. This is because they are synthesised to have structures that allow them to bind to the body’s cannabinoid receptors. The drugs originated in the late 1980s to early 1990s, by chemists who understood how these receptors were bound by the active ingredient of the cannabis plant, ∆9-tetrahydrocannabinol (∆9-THC), which produces the ‘high’ associated with this drug. Synthetic cannabinoids were therefore produced to imitate this effect, by binding the cannabinoid receptors in a similar way. The use of these substances increased hugely in the last decade or so, particularly in Europe, as the chemicals involved were not controlled or regulated by law. In addition to this, very often as forensic drug analysts became familiar with the chemical structure and nature of one legal high, and therefore were able to test for it, the drug producers would adjust the chemical structure of the substances slightly so that the drug’s effect remained the same but the chemical was undetectable in standard drug screening tests. This, in combination with a rise in incidents of poisoning and the number of fatalities, led to an increasing need to regulate these drugs.

Controlling these substances has been very difficult around the world, as no countries had laws to regulate them. However, in the UK, this changed in 2016, when the Psychoactive Substances Act came into force. This law is a blanket ban on the production, distribution, sale and supply of these substances, and these activities are now punishable by up to seven years in prison. Legal highs are added into the list of banned substances as they are discovered, after forensic drug analysts have determined the chemical structure of the substance, and the health risk posed by the compounds has been assessed. However, our pharmacological understanding of these substances is still very limited, and this has slowed progress in identifying new psychoactive substances. New substitutes for legal highs evolve at such a rapid pace that is difficult for the authorities to keep up with, and the drug producers are generally always ahead of the law. If you would like to read more about legal highs, this BBC article gives some more information about them, and this BBC News article discusses the introduction of the Psychoactive Substances Act in 2016.

In answer to the question about drug profiling and when this would be done, UK forensic service providers all have their own drug testing labs and these will all have the capability to do drug profiling. However, drug profiling is not actually done very often as it is very costly, and usually the key issue is just to identify an unknown substance as being a specific controlled drug. This is done using presumptive testing and then confirmatory testing such as GC-MS (gas chromatography mass spectrometry) or TLC (thin layer chromatography). Drug profiling would involve more detailed chemical analysis to determine the components present in the substance in question and to estimate the amount of each component (e.g the drug, cutting agents, impurities). This can be useful in linking different batches of drugs together, and also in linking drugs to a production site/lab. For example, a sample of heroin might also contain diamorphine, paracetamol, and caffeine, and potentially also things like mannitol (a sugar) or anti-fungals. In terms of central coordinated databases of drugs, forensic providers maintain their own databases and regularly make this information available to police, documenting the different types and quantities of drugs found in a given time period. There are also some projects collecting data to monitor seizures of different types of drugs when recovered in relatively large quantities, and these can be used for intelligence purposes.

With regards to determining the origin laboratory of drugs seized, the majority of drug testing done in forensic laboratories is not done to identify the origin lab, the majority of the work done by these labs is to identify what drug someone was in possession of. Linking to a source lab is therefore relatively rare, and the forensic analysis part of drugs investigation is often completed very quickly. However, if the chemical structures produced in different labs are different then they can be differentiated using chemical analysis and so this can be a very powerful method. Similarly, the type and context of the case would determine whether the police/prosecution would request that the forensic laboratory test the purity of a drug. If the police are only charging someone with possession of a drug then the purity would not be important and the forensic analysis would simply involve identifying the drug. However, if someone was being charged with supplying a drug, then the purity would be tested in order to estimate the street value of the sample seized, and this could influence a sentence or fine later on.

One of the questions also asked about prescription drugs—our course didn’t cover prescription drugs, but that doesn’t mean that they are not of interest to forensic laboratories. Forensic labs will regularly analyse samples of prescription drugs, if requested by the police. This might be because the identity of some tablets is unknown and the police want to know what they are, or because the suspect doesn’t have a prescription for the drugs. In addition, many prescription drugs are also controlled, so they can be possessed with a prescription but are classified as controlled, e.g. in the UK diazepam is a drug that can be issued with a prescription but it is also a Class C controlled substance. There is also a pharmaceutical database containing information about prescription drugs that can be used by forensic labs to identify unknown samples.

Anne Weatherly asked about what would happen if the legal team acting for a defendant in a criminal case were able to introduce an element of doubt into the evidence presented by a prosecution expert, and whether this would mean all earlier cases this expert had been involved with would be called into question. The answer would depend on the case context and what the issue was that introduced the element of doubt. There are often different ways of interpreting the same piece of evidence and the prosecution and defence experts might quite legitimately draw different conclusions from the scientific evidence in a case, and this happens frequently. This is how the criminal justice system should work—if there are different explanations for a particular piece of evidence then the jury should hear all of those potential explanations so that they can make as informed a decision as possible. However, if the expert in question had done something that could be demonstrated to be wrong, e.g. they had not followed procedure, or had fabricated or incorrectly interpreted results, then it is possible that previous cases they had been involved with might be reviewed. There have been a couple of examples of this in the media in the UK recently, including questions over toxicology testing at Randox Testing Services and just last week questions were raised over tests carried out by an individual scientist at the Metropolitan Police Forensic Services.

John Lateanoasked about crime scene investigators and whether the individuals in white suits at a crime scene are police officers or trained forensic staff. The answer to this depends a bit on jurisdiction as in some countries, such as the USA and South Africa, crime scene investigators will tend to be police officers, whereas in the UK they will not be police officers, although in some parts of the country they may be civilians employed by police forces. However, they will always be trained in the forensic investigation of crime scenes and will therefore know what to look for and how to find it. As John suggests, coordinating and managing these specialists can be very challenging and may involve very long and unsociable hours for them, and they may often be called to scenes at very short notice and at all times of the day and night.

Finally, Michael Boyle asked about Rapid DNA and its use in the UK and how this compares to its use in the USA. Rapid DNA technology is in use in the UK, most notably at Key Forensics, who offer RapidHIT ID DNA testing, and recently received accreditation for this technology. In addition to this, the National DNA Database Strategy Board have been carrying out some pilot studies looking at this new technology, which may therefore become more widely used, although it should borne in mind that there are still some concerns over the use of this technology as outlined in this article in Forensic Magazine. Until recently, LGC offered an alternative rapid DNA testing technology called paraDNA, but it is my understanding that this is no longer available.

All that remains now is to say that I hope you enjoy the rest of the material in Week 6. The video revealing what really happened will be made available at 16:15 BST this Friday 18 May 2018 and we are asking you to vote up to 16:00 BST on Friday 18 May 2018 for whether you think Mr Ward is guilty or not guilty. We really hope you will take the time to vote, and we would love to see lots of responses. I would also encourage you to vote according to your analysis of the evidence, and not on your gut feeling. This week we have been looking at a logical system for bringing together evidence and analysing it and thinking carefully about what it means from a scientific point of view. You should therefore focus on the science, work through it all logically and base your decision solely on what the evidence tells you. I really hope you have enjoyed the course, it has been a real pleasure interacting with you and reading all your comments and questions. I have really enjoyed seeing how interested you have all been in the case, and how much discussion you have had about it each week.

Thank you very much for joining us for Introduction to Forensic Science and don’t forget to cast your vote before 16:00 BST this Friday 18 May 2018.

- Dr Penny Haddrill

Share this article:

This article is from the free online course:

Introduction to Forensic Science

University of Strathclyde

Contact FutureLearn for Support