Photo of Laura Reaney

Ask Laura

Please post your questions for this week in the comments section below. Laura will select the most liked/interesting questions and publish her response to these on this step by Wednesday of Week 2.

First of all, I’d like to extend a very warm welcome to you all, and thank you for joining the Introduction to Forensic Science course. It’s great to see so many people from all across the world taking the course and getting involved with the discussions. Thank you for all of your great questions this week, and for all of the positive comments about how much you are enjoying the course.

It is also fantastic to see you all helping each other and sharing information, for example Jo B’s links to pathologist details in response to Sophie Laws. I wish that there was the time to answer all of your questions but I’ve focused on those that were most popular this week.

Crime Scenes and Crime Scene Managers

Shaaista Hassan asked about the specific details of a CSM’s position, roles and responsibilities and this will differ depending on jurisdiction, and to some extent the context of the case in question. This is particularly well illustrated using the example of the UK, which covers three jurisdictions (and legal systems); England & Wales, Scotland and Northern Ireland. In Scotland, CSMs will usually be police officers, whereas in England & Wales, they will tend to be trained civilians. However, in general, a CSM’s role is a very important one, and they are responsible for the initial assessment of a scene, planning the forensic strategy and agreeing this with the Senior Investigating Officer (SIO), briefing scene personnel and allocating appropriate numbers to individual aspects of scene examination (which will differ depending on the detailed requirements of the case), advising the SIO on the investigative potential of different evidence types and the value of using specialists (which will also depend on the detailed requirements of the case), and coordinating the individual experts within the overall scene (which as several of you spotted could get logistically and financially quite complex). They are also responsible for managing the welfare of all scene personnel, carrying out health and safety risk assessments and implementing control measures as well as releasing the scene. If you are interested in finding out some more, then this article gives some further information about the role, as well as the skills and qualifications needed to become a CSM, and the career path that a CSM might follow.

Katie O asked a question about how long a scene is taped off and there is no fixed answer to this, it all depends on the nature of the scene and of the crime itself. The CSM will always try to release a scene as soon as possible, especially if it someone’s home or a public space, but equally they will wait until they are sure that all evidence has been recovered; most commonly this is hours or days but it can be months. A recent example of this is the tragic incident at Grenfell Tower in London; the site remained a crime scene from June 2017 until August 2018.

Caroline Bowyer, Robert Bean and David Brown all asked an interesting question about the impact of emergency responders at a scene. There are a couple of different aspects to the answer to this. Firstly, all individuals who may come into contact with evidence in a case, e.g. police officers, paramedics, medical staff, crime scene investigators and laboratory scientists will have a DNA sample taken and recorded in a staff/visitor elimination database, and any DNA profile generated in a case will be searched against this database to check for/detect any contamination. In addition, fingerprint databases may be kept containing fingerprints for all front-line police/crime scene staff whose fingerprints may be found at crime scenes. Additionally, if evidence such as footwear marks are found at a scene any individual who has been at the scene would have their footwear recovered for the purposes of elimination.

The second aspect to consider here is training of first responders to minimise any affect on the crime scene without compromising the importance of their own role. This varies depending on country and jurisdiction. In many countries, police officer training includes only very basic coverage of forensic science, whereas better scientific training and awareness for police officers and other members of the criminal justice system, such as lawyers and judges, would be extremely valuable. In the UK a prime example of this is fire scenes; apart from damage done by the water which is unavoidable, historically it was common practice for firefighters to remove furniture etc from a property as they extinguish the fire, however this could significantly compromise any forensic evidence. Today, a more collaborative approach using awareness training between the fire brigade and forensic providers has led to a greater understanding from both sides to allow both parties to perform their duties to the best of their abilities with minimal impact; they do not routinely throw out the furniture!

There were also some questions relating to outdoor crime scenes, how these are affected by environmental conditions and how this is managed. Chidimma Irozuoke and Amanda Wilbur asked questions relating to this topic. The answer will depend on the type of case being investigated, and for more serious crimes, more resources can be deployed more quickly. If weather conditions are bad, some measures can be taken to try and protect the scene and any evidence, such as the tents mentioned. However, sometimes this is not possible and weather can be unpredictable and so the recovery of evidence must be prioritised in order to secure as much of it as possible before the conditions destroy it. The crime scene manager may need to make some very difficult and quick decisions about how to deploy resources and what to prioritise. This is also related to the question of how time affects the recovery and viability of evidence, and whether evidence remains viable if any significant period of time elapses between evidence being deposited and recovered. There are two factors to consider here. Firstly, the length of time that evidence would remain viable for analysis would depend on the conditions in which the sample had been stored. If a sample was at a crime scene that was outdoors, and there was a lot of rain, or very high temperatures or humidity, then samples of a biological nature such as DNA, body fluids and fingerprints could deteriorate and degrade very quickly, and this is a major challenge of managing a crime scene of this nature. However, if samples were indoors, in dry environments that were not subject to major fluctuations in temperature etc., then samples could still be analysed after months or even years.

Finance and Resource Management

This brings us on to another set of questions, which related to financial and resource constraints around the provision of forensic services. Jean Crapper, Bethany Lewis Gregg Jolley, Viv Watts, Paula Santos, Tony O’F, Maggs Carver, Harry Craig, Sian Docherty and Nicky C all asked questions related to this.

The situation in the UK is complex, substantial cuts to police budgets have led to more techniques being done “in house by the police” and very little profit in the market to enable a stable economy of forensic science by external providers. However, it is true to say that Police and Forensic Providers are still fully committed to maintaining the highest levels of quality and integrity

With limited budgets, police may not be able to request a full range of forensic tests on every exhibit in their investigations but scientists will advise on which items and evidence types to prioritise. For example, in a case of a “stranger rape” a staged approach might be used, where intimate swabs are examined first and only if no suspect’s DNA can be identified then they will move on to the next stage – the underwear. Alternatively, if it is an assault between two flatmates, the scientist may advise that it is not appropriate to look for hair/fibre trace evidence because the evidential value is low given that they live together and there is an expectation that they would have transferred hairs/fibres innocently. This is however a very difficult issue; it is true to say that, understandably, budgets for serious crime are much higher than volume crime and therefore more resources, including specialists, can be employed but only where it is deemed of potential evidential value.

In terms of specialists, such as anthropologists and entomologists etc, there are far fewer experts in these fields then the more commonly encountered forensic biology, forensic chemistry and pathology disciplines. These experts are generally self-employed or work at research institutes, museums and universities rather than full time at forensic providers. Yes, not every geographical area will have every expert, but this does not mean that the provision of these types of forensics is based on location as the experts in these fields widely travel and will except casework wherever needed.

In May 2019, the UK House of Lords’ Science and Technology Select Committee published its much-awaited inquiry report into Forensic Science Strategy which you can read here. It outlines some concerns in research, funding and leadership in forensic science in England and Wales. In addition, the forensic science community are pushing for statutory powers to be given to the Forensic Science Regulator, who is responsible for ensuring that high standards are maintained across the market, to make sure providers are delivering quality and consistency of service. It remains to be seen how the provision of forensic service in the UK will change over the next few years.

Training and Qualifications

There were also several questions this week related to becoming a forensic scientist and what qualifications are needed. Romaissa Chalabi, Gina T, Sue Hampson, Garrett Delhommer and Linda H all asked questions relating to this. In terms of the qualifications needed to work in forensic science, a Bachelors degree in any traditional science subject is often sufficient for getting a job in forensic science, although a lot of the scientists working in forensic labs around the world have Masters level qualifications. Some scientists will do a forensic-related degree at undergraduate level whereas some will do a pure science degree at undergraduate level and then specialise in forensic science at postgraduate level. 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 us here 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 at the university. Some scientists will also undertake more specialised degrees such as forensic anthropology, or forensic toxicology, although every forensic organisation will have their own procedures and specialisations and so scientists will always be trained when they start working at a forensic laboratory regardless of prior qualification and experience.

CSI Effect

John Dew asked about the so called “CSI effect”. This is a term that is used to describe changes in public perception and understanding of forensic science following the rise of television programmes like CSI and how they have affected the field of forensic science. Whilst it is useful to raise the profile of the work that forensic scientists do, and for the general public to become more scientifically aware, it has also been shown that there have been some less positive impacts of these types of programmes. For example, it is thought that the proliferation of shows of this type has led to juries having unrealistic expectations of what can be achieved by forensic scientists, and also that they may come to give too much weight to forensic evidence. This has been termed the ‘CSI Effect’ and you can find out more on this Wikipedia page.

Impartiality and Integrity

There were a large range of questions which I have categorised together as they fall under the terms impartiality and intregrity. These include questions from Advocate Sardar Sameer, Wendy Carey, Beth Harrison and Ian Horne.

A fundamental concept of forensic science is that the scientist’s duty is to the court, regardless of whether they are technically paid by the prosecution or the defence. It is the job of the forensic scientist to evaluate any evidence in accordance with both the prosecution and defence’s hypotheses and using sound scientific principles which must be widely recognised to make their opinion on the evidence. A forensic scientist will not be allowed to give expert witness testimony if they do not meet the admissibility standards outlined in their country i.e. what is or is not allowed as evidence in court, in the America this is the Frye Test and Daubert Standard, in the UK this is governed in part by the Civil and Criminal Procedural Rules. A forensic scientist is working in insolation on evidence in only their own area of expertise, they should NEVER comment or draw any inference as to the guilt or innocent of an individual, this is a matter for the court. The scientist should always be impartial, unbiased and objective – Von Moss they should never use their “gut feeling” or intuition. There are many standards, quality assurance and measures in place to overcome any bias but there are still contentious schools of thought in relation to unconscious bia, which is harder to recognise and control. In the UK we use a method known as Case Assessment and Interpretation and this framework serves us well to minimise and potential bias or influence.

Crystal Dieken also goes on to ask why everything isn’t tested to show that someone is the perpetrator of a crime and that this can lead to miscarriages of justice. A similar question was asked by Jijy Rohini Padmakumar and really there is no simple answer to this. As mentioned previously, there are frameworks in place to manage what exhibits should be examined & for what types of evidence and genuinely this has been a positive step in streamlining processes and resource management without compromising on quality and still ensuring that all relevant evidence is recovered and analysed, however, clearly sometimes something goes wrong. One of the biggest parts of a forensic scientist’s role as an expert witness is to clearly outline the limitations of the evidence, science and techniques used so that the jury can make their own informed decision about whether they agree with the conclusions and opinions of the scientist.

Many miscarriages of justice (but not all) are as a result of advanced techniques that were not available at the time, such as ABO blood grouping vs today’s more discriminative DNA profiling, or errors made by the scientist’s in the interpretation of their findings and the presentation of (or failure to declare) their evidence in court, one of the most common being the “Sally Clark” case whereby the two experts spoke outside their area of expertise and failed to disclose critical findings; these were not as a result of evidence not being recovered or only some exhibits being examined. Today there are stringent guidelines for the interpretation of evidence and in the UK at least, no individual can be convicted on a single piece of forensic evidence alone. Other miscarriages of Justice have arisen from accidental mistakes, for example where an item has been searched for blood but it was not seen (Damilola Taylor) and again we now have procedures in place for certain exhibits to be examined twice if initially negative or the findings to be corroborated by another individual.

Cold Cases

Angela Bayne, Donna Gaddass, Jessica Attardo and Julie Stanwick asked about cold cases, technical advancements and retention. There are definitely cases that have been solved as a result of technical enhancements and many of these are related to the development of DNA profiling techniques and enhancements in the sensitivity of bodyfluid detection and “touch” DNA. I’ll post some more case examples next time once you’ve completed the DNA week!

In terms of retention in the UK, evidence pertaining to the most serious offences and also unsolved crimes is retained for 30 years, although this is a guideline and some may be kept indefinitely. However, yes, there are items that have disappeared over the years. I’m not aware of anything going missing from “new” cases over the 10+ years I’ve been working in the UK but I do have firsthand experience of items being lost or misplaced from cold cases that I have worked on, where the samples that were extracted or evidence recovered exists (for example, hairs, fibres and semen stains) but the original item (e.g. undergarments) cannot be located. You can read more about the different retention processes and timeframes here

I just wanted to add one more thing, which is in response to the questions about the tests on this course. FutureLearn have responded to this to say that if you choose not to upgrade, you should feel free to move on to the next week of material whenever you feel ready, without taking the test. The test is intended to help learners who are looking for summative assessment and a Certificate of Achievement to prove their learning; we know this will not be the case for all learners.

Sorry I couldn’t address everyone’s questions this time but many thanks for engaging with the content and I hope you find these answers of interest. There’ll be another opportunity to ask any questions in Week 3, in the meantime, enjoy!!

Share this article:

This article is from the free online course:

Introduction to Forensic Science

University of Strathclyde