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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.

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. There were some really interesting questions this week, and it was great to see so many of the questions being answered by other students; you all worked really well together this week.

One of the topics that came up in several questions was legal highs, and several of you contributed to some interesting discussions about these substances, including Robert Sserubiri, Susan Burton, Tracy Harris, Kathleen Warburton, Martin Sweeney, Krishnamurthy G, Sarah Quilter, Jill Hazel, x Svargo, Colin Armstrong, Ines Chr. Hey (Bowden), Kayla Wildman, Richard Aggus, Charlotte Louise Butterworth and Denni Morrison. The terms ‘legal high’ or ‘new psychoactive substances’ refer to chemicals that produce similar effects to illegal drugs such as cannabis, amphetamines and cocaine. These chemicals are produced with the aim of avoiding the current laws that control 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 19080s 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 has 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 the rise in incidents of poisoning and the number of fatalities, has led to an increasing need to regulate legal highs.

Controlling these substances has been very difficult around the world, as no countries have had laws to regulate them. In the UK, this changed earlier this year, on May 26th 2016, when the Psychoactive Substances Act 2016 came into force. This new 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 article discusses the introduction of the Psychoactive Substances Act 2016, earlier this year.

Kelley Peter also asked about the issues of relying solely on presumptive tests for the forensic identification of different substances. These types of test exist for both biological substances such as blood, saliva and semen, and for chemical substances such as drugs and explosives. All of these tests are based on a colour-change test that indicates whether a substance may be present or not. However, for all of these tests, there are a variety of substances that can cause false positive results on the tests, which means that the results of these tests cannot be used to definitely conclude that a substance is present. As such, a presumptive test cannot be reported formally, and a forensic scientist would not testify in court about the results of such a test. For example, the presence of cleaning products such as bleach can lead to false positive results for the presence of blood, as can various household substances such as horseradish. False positive results on presumptive tests for drugs have also been reported, as a result of cross-reaction with drugs that are not illegal, including some prescription drugs, such as aspirin. In addition, some everyday substances give false positive results on these tests, including, coffee, chocolate and soap. The issue with this potential for false positive results means that presumptive tests cannot be relied upon, and more detailed confirmatory analysis needs to be carried out before a forensic scientist can conclude that a substance is present. For example, after a presumptive test for semen, microscopy is carried out to visually detect the presence of spermatozoa, and after presumptively testing for drugs, analytical methods such as gas chromatography mass spectrometry are carried out in order to determine the chemical composition of a sample. These confirmatory tests allow more definitive conclusions to be made about questioned substances, and so the results of these tests can be reported in court.

Gail Wright asked about whether it would be possible to test the clothing of some of the individuals involved in this case for gunshot residue (GSR), and this question has arisen in previous weeks as well. In general terms analysing samples for gunshot residue could be useful, and in some case contexts could give you some useful information. However, there are some important limitations of gunshot residue evidence, particularly in this specific case. The first is that in any shooting, particles of gunshot residue are transferred onto surfaces near to where the gun was fired, including skin, clothing, nearby surfaces etc., but they are also lost very quickly. Many forensic laboratories will not accept items for examination for gunshot residue if they are collected more than a few hours after the incident took place, as it would be unlikely to produce any useful information. The second limitation, specific to this case, is that here we have a situation where two people were shot inside/around a vehicle, and so it is likely that there will be a lot of gunshot residue all over those people and the inside of the car. Mr Ward’s hands could be tested for gunshot residue, but if this is found then it could be explained by him touching his own arm where he was shot, touching Mrs Ward or touching the inside of the car. So, whilst it might be possible to identify gunshot residue, we have to think about whether this would actually be useful investigative information.

Mark Ezegbogu asked about the difference between forensic toxicologists and forensic chemists, and the types of analyses these analysts carry out, and Pamela Wilson, Sheryl Browne and Jane Ridson were also interested in this topic. Kelley Peters correctly explained that forensic chemists or forensic drug analysts will carry out analyses on seized drugs, such as powders and pills, usually with the aim of identifying what substances are present and whether any of them are controlled. Forensic toxicologists will analyse biological samples taken from e.g. a deceased individual or an intoxicated individual, to determine what illicit substances may have been consumed and metabolised by them. Rafael Lopez Garcia asked why we did not include any information about how to detect drugs in biological samples taken from an individual’s body. This is what forensic toxicology relates to; samples of blood, urine and hair can be taken and examined for the presence of drugs, and in a post-mortem, other samples may be taken, such as the stomach contents or the vitreous humour of the eye, which is often used when bodies are very decomposed. Solid tissue samples can also be taken, including samples of the brain and liver. Some of you correctly pointed out that there was no toxicology report on Mrs Ward reported in the case, including Nick Tingley, Kayla Wildman, Elaine Groom and Michelle Carter. Toxicological analysis can produce very important forensic evidence, and this is one major area of expertise that forensic scientists can specialise in. Unfortunately, we simply did not have time to cover every type of forensic evidence in six weeks, and so it was not possible to include toxicology in the course at this time.

Christian Vincent also asked about how to go about getting jobs in forensic science in the UK, and Oshin David asked about Masters qualifications in forensic science. As I said in the first week, in the UK, forensic provision differs depending on the region. In Scotland, provision is by the Scottish Police Authority (SPA) Forensic Services, which is a government owned organisation with four laboratories in Glasgow, Edinburgh, Dundee and Aberdeen. The situation in England and Wales used to be similar, with the government owned Forensic Science Service providing services to police forces. In 2012 the UK government closed the FSS, and forensic services are now either provided by private companies or have been moved in-house in police forces. Finding jobs in forensic science usually involves looking for positions advertised, either on the SPA website or on the website of any of the commercial forensic providers in England, such as LGC, Cellmark, or Key Forensics. In terms of the qualifications needed to work in forensic science, a Bachelors degree in a science subject is often sufficient for getting a job in forensic science, although a lot of the scientists working in forensic labs in the UK have Masters level qualifications. There are a variety of postgraduate qualifications in forensic science across the UK, and the Chartered Society of Forensic Sciences accredits a number of UK and international courses. One of the MSc Forensic Science courses in the UK is offered by the Centre for Forensic Science at the University of Strathclyde, and if anyone would like any further information about this, you can find this at the course website, or you are welcome to contact me by email if you have any questions about the MSc course.

Finally, one question that you may be wondering about is whether the material will remain available for you catch up on anything you missed, or to come back and look over again. The answer is yes, the material will be available to you indefinitely, so please feel free to come back and go through the material again, or look at things in more detail if you want to.

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 GMT this Friday, 2nd December, and we are asking you to vote up to 16:00 GMT on Friday 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 the Introduction to Forensic Science MOOC, and don’t forget to cast your vote before 16:00 GMT this Friday!

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This article is from the free online course:

Introduction to Forensic Science

University of Strathclyde