What is forensic science?

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Forensic science is a very broad term. It covers any aspect of science which may be of use in a court room.

Forensic is term from a Roman times related to the forum, the gathering of people who also judged on criminal acts. So forensic science means to put scientific evidence before the people.  In current use people often shorten forensic science to forensics.


The forensic science process is often termed ‘crime scene to court‘ – these steps are explained below.


Crime Scene

In many peoples mind forensic science is the crime scene analysis type of work.  This is seen regularly on TV shows such as CSI.  The scenes are investigated by people dressed in special clothing and shoe covers designed to preserve any evidence  and prevent contamination of the scene.  These are known as Scenes of Crime Officers (SOCOs), more recently becomming known as Crime Scene Investigators (CSIs).  At the scene the officers may do various examinations teem selves, such as presumptive testing for body fluids and finger mark collection.  Presumptive testing gives an indication as to the presence of certain body fluids and allows the SOCO/CSI to target collection of items to send for further tests.

A SOCO will write a report for each scene they attend detailing what they did and any findings.  This is submitted to court if the case gets that far and the officer may be called to give evidence if the court requires some of their evidence to be explained.


The collection of evidence is crucial to a case.  Once evidence is collected it is usually sealed in evidence bags and submitted to a laboratory for further analysis. The evidence is tracked through the process so it can be seen who has handled each item, known as an exhibit, at any time. This process of recording the exhibits movement is known as the chain of custody.


Laboratory analysis

This stage in the forensic process may involve the submission of evidence to specialist laboratories.  The traditional division was mainly along the biology and chemistry divide, but there are a great many differing sub specialities.

Many Police forces in the UK now have their own laboratories for more complex finger printing techniques, and occasionally more complex analyses.

In the chemistry side of things you would find analysis of drugs, paint, fibres, fire accelerants, alcohol and gun discharge residue.

Forensic biology includes anything to do with analysis and detection of  body fluids such as blood, semen and saliva.  Once these fluids have been detected they are often subjected to analysis for DNA.


There are many specialities of these disciplines and many other areas which may be used in criminal cases such as forensic toxicology, blood spatter analysis, entomolgy (study of insects found at a scene), palynology (pollen analysis) and so on.


Interpretation and court

Once these tests have been completed, the senior scientist, often called a Reporting Officer, will write a report for the case.  The reporting officer will have been trained at the laboratory and often has higher level scientific qualifications.  This is submitted for the Police and prosecution to help them determine the charges to be laid (or not).

If the case goes to court the reporting officer will attend as an expert witness.  To present evidence as an expert witness the reporting officer usually will have a combination of qualifications, on the job training and several years experience.  Most laboratories will arrange for court training for their reporting officers.  Court going can be stressful at first but most expert witnesses find that over time they get used to the way the court works.


The laboratory will usually have some form of accreditation to undertake the work, which shows the analyses meet a certain standard and may be relied on.  I will write more on accreditation at another date.


I hope this whistle stop overview of forensic science helps.  Perhaps you are considering a career in these areas or wish to study for a degree in forensic science?  If so I wish you luck and I hope you enjoy this varied and interesting world.

Now you have read this introduction have a look at the blog to see what current issues are being discussed: BLOG



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About Dr Tom Bassindale

Dr Tom Bassindale is a forensic scientist, and the founder of We Are Forensic. He is currently the subject lead for chemistry and forensic science at Sheffield Hallam University. He's managed hundreds of forensic toxicology cases, and is an experienced court witness. He has specialist expertise in forensic toxicology and drug testing in sport. And yes... he watches CSI.