The Oxford Science Lecture Series

DR ANGELA GALLOP

Science Director, Forensic Alliance

"Forensic Science: Principles and Practice"

Martin Wood Lecture Theatre, Oxford, 27th June 2002

On June 27th 2002, Dr Angela Gallop, current President of the Forensic Science Society and Science Director of one of the UK's leading independent forensic science laboratories, gave a fascinating lecture on the topic of forensic science. Dr Gallop endeavored to describe the guiding principles of forensic science and to illustrate the use of these principles in a practical setting by describing several case studies.

Throughout the talk, Dr Gallop's own fascination with the subject of forensic science came through very strongly. She made it quite clear that those who take up a career in forensic science will have a tough path to follow. A forensic scientist will have to examine many deeply unpleasant items, will often work in a very difficult environment to impossible timescales and will have to present her findings to a lay audience half of whom are openly hostile. She must be robust, physically, mentally and emotionally, in order to cope with the job. However, it was clear from Dr Gallop's own enthusiasm for her work and the excitement of the science itself that there are compensations and that forensic science can be a very interesting career path indeed.

Dr Gallop began by giving a brief history of forensic science labs in the UK. Until 1991 all forensic science was carried out in Government labs by the Home Office Forensic Science Service. After that date the Forensic Science Service became a government agency and the market was opened up to competition. This led to the founding of several independent forensic science companies, including Forensic Alliance who currently run labs at Culham and Riseley.

The main guiding principle of forensic science was laid down by E. Locard in 1910: "Every contact leaves a trace". The job of forensic scientists is to search for these traces. In doing this it is vital to recognise the potential risks of contamination and to avoid them. For example, workers at Forensic Alliance's labs wear surgical scrubs in the lab in order to avoid contaminating samples with fibres from their own clothing. Items which are found at crime scenes are packaged immediately in securely sealed bags and control samples are taken where possible.

There are several subdisciplines within forensic science, including forensic biology (search for evidence in offences against people), forensic chemistry (offences against property), toxicology (suspicious deaths and drug abuse), drug analysis, and others such as ballistics, computer forensics, forensic psychology and firearm forensics.

Forensic biology, Dr Gallop's own discipline, is heavily focussed on DNA analysis. DNA is highly discriminatory (a DNA profile is unique within 10 million people) and long-lasting. DNA samples can often be found at crime scenes on jewellery, saliva on drinks cans and cigarette butts, clothing stains, dandruff and blood. The tiniest sample is needed now to get a DNA profile - less than a pinhead-sized bit of blood is sufficient. The UK has the most advanced DNA database in the world, containing DNA data on 1.7 million people (all those charged with crime in England and Wales are put onto the database). In a typical week there can be over 1500 matches in the database, and the hit rate is around 45-50%.

An example of the use of DNA profiling in solving a crime is the murder of Cynthia Bolshaw, the 'Beauty in the bath' case. This murder was solved after 16 years when advances in DNA-profiling technology enabled a DNA profile to be produced from a very small semen sample on a piece of evidence which had been stored since the original investigation. Publicity brought a suspect to light and his profile matched that of the sample.

Forensic biology is also concerned with how a stain might have arisen. For example, pattern analysis of blood stains may provide information about the type of weapon used and the number of blows struck. It may also provide links between the crime scene and suspects.

For example, in the case of Billie Jo Jenkins, analysis of very fine blood spots on the clothes of the main suspect was done by aerosol experts. The defence stated that these could have occurred when the defendent found the victim already dead. But the forensic experts determined that this type of stain could not have been due to this as the forces involved in producing such a spray were too great.

Another major area of forensic biology is the study of textile fibres. Forensic science can recover and study minute textile fibres from crime scenes, using sticky tape to pick up the fibres and then targetting fibres of interest to be analysed. They can be used as evidence of contact to link people, people and objects and people and places. Currently there is no good database of textile fibres as there are just so many different ones, but this type of analysis can be very useful in a comparison of fibres - for example, comparing fibres found at the scene with the clothes of the suspect.

For example, in the Sarah Payne murder inquiry, a link was made between fibres in the van owned by the suspect and fibres on the bag in which her body was found. Also a single hair found in the van was found to match Sarah's DNA profile.

This case illustrates another principle of forensic science which is that the greater the number of tests in which traces match, the greater the confidence we can have in the result.

Dr Gallop also talked about the area of forensic chemistry, which is used to analyse evidence in cases of breaking and entering (eg glass particles on clothes), arson and chemical identification, and drugs analysis, which is used not only to identify drugs but also to analyse packaging materials used to contain drugs. For example, it may be possible to find links between the packaging found on a user with that of a particular dealer in drugs.

She concluded her talk with the bald facts facing a potential forensic scientist mentioned at the start of this report. This honesty about the drawbacks of the profession was refreshing, but was more than compensated for by her clear love of the discipline. The whole talk was truly fascinating and inspired all to think about the impact and use of forensic science in solving crime today.

Catherine Hobbs