“I have a colleague who has expertise in soil forensics, did a PhD on the mineral characterisation of soils. We could do an elemental analysis and compare to the available soil and geochemistry databases….” says Dr Nikki Alexander (Emilia Fox) in tonight’s (Thursday 21st January 2010) edition of the BBC’s Silent Witness.

The colleague she is referring to is Dr Lorna Dawson (pictured). As head of the Soil Forensics Group at the Macaulay Land Use Research Institute in Aberdeen, Lorna’s research into plant and soil interaction spanning more than 20 years has taken her from rural locations to courtrooms and more recently, behind the scenes of a television drama.

Lorna was involved in the new series of Silent Witness, the BBC hit drama featuring forensic experts who investigate crimes and murders. With her extensive experience in soil forensics, Lorna was required as an advisor for the filming of a new episode, which is due to be aired tonight. She provided advice to the programme’s writers about site selection and soil forensic analysis.

Lorna says, “I was sworn to secrecy about the details of the episode, but I could say that it involved a murder story in an outdoor setting and the use of soil forensic analysis. I really enjoyed working on this story; it’s great to see programmes like Silent Witness making the use of forensic science more accessible to the public.”

As well as helping television’s fictional characters to fulfil their roles, Lorna also assists in the solving of real-life crimes through her work with the police and the criminal justice system. In recent years the application of soil forensics to criminal cases has become more frequent, leading to its use in high profile cases such as the Sarah Payne and Soham murders. By using the unique signatures of natural minerals, organic, and synthetic components found in the soil, experts can help locate the graves of murder victims or link a suspect with a crime scene by examining dirt found on clothing, footwear and even in the tread of a vehicle’s tyre.

Lorna explains, “Every patch of soil has its own ‘fingerprint’ which means that we can help identify the location that it came from. Analysing the soil is carried out in three different parts. Firstly, the inorganic part that is derived from the rock underneath the soil provides the mineral signature, and links to the underlying geological map unit. Secondly, any vegetation that has grown in that soil provides the organic signature linking to the plant composition, and thirdly, the living organisms that inhabit the soil provide its DNA.”

In addition to her police work and making science more accessible, Lorna is currently working on a two year project to compile a database that holds the signature values for every type of soil and vegetation type in Scotland. Once completed, the database will serve as a reference source for criminal investigations as well as policy makers wishing to determine areas of soil that are most susceptible to climate change. The records will also benefit other scientific researchers and farmers who want to make more efficient use of fertilisers for crop growth.

Lorna says, “Soil feeds into the rest of our environment and is an incredibly important material, not just in terms of its scientific uses, but also for our health, through filtering the air that we breathe and providing the food that we eat. The work that we do at the Macaulay Land Use Research Institute is helping to raise the profile of soil and the potential uses of soil signatures across the UK, and subsequently increasing its application in areas such as criminal and environmental investigations and the agriculture industry.”