Explainer: Forensic science
FORENSICS AUSTRALIA – There has always been a role for forensic science in criminal investigations, but these days, with criminals committing clever, well thought-out crimes more often, it’s now an essential tool for criminal investigations.
Without question, the field of forensic science has come a very long way since its recorded beginnings around 700AD, when the Chinese used fingerprints to establish the identity of documents and clay sculptures, thereby identifying their authenticity.
Since that time, some notable discoveries have occurred – such as the use of chemistry to analyse myriad inks, drugs and minerals and the more recent discovery of DNA which has become a mainstay tool for identifying perpetrators and excluding the innocent.
There are three core disciplines that constitute forensic science – medicine, chemistry and anthropology – followed by an extensive array of sub-disciplines.
- Chemistry (chromatography, spectroscopic analysis, pH and other chemical tests)
- Biology (entomology, fingerprinting, behaviour, hairs, DNA testing etc.)
- Physical science (blood spatter analysis, ballistics, structural analysis, car movements in car accidents).
When a crime is committed and the forensic team is called in, there are many experts who cover their specialised fields. Although all these people could be considered forensic scientists, they have different skills and focuses.
The minimum requirements for a criminal investigation are:
1) Field officers: these are technicians who visit the crime scene and collect physical evidence that may be related to the crime.
They also document and record the scene by taking photographs and videos.
2) Lab officers: these are technicians who analyse and complete tests on the evidence collected by field officers.
Sometimes the above two roles are further broken down into expert areas, including:
Crime scene investigator: people who visit the scene of the crime to find, collect, protect and transport all the evidence they have collected back to the crime lab.
Latent print examiner: specialists in fingerprints, palm prints and footprints.
Firearms examiner: experts in determining what sort of firearm was used by comparing bullet and shell casings, and searching for and identifying gunshot residue.
Tool mark examiner: similar to the fingerprint examiner, but rather than looking for human fingerprints they look for distinctive marks that may have been left by tools the criminal(s) used.
Document examiner: specialists who determine authenticity and authorship of documents left at the scene.
They also look for any alterations that may have occurred to original documents and may be asked to determine whether a particular copier or typewriter has been used in the creation of a document.
- Trace evidence examiner: individuals who analyse and compare any traces the criminal may have left behind.
These people are responsible for analysing and comparing hair, fibres, glass, soil and paints to work out type and origin.
While the above roles relate to all crimes, there are some additional experts who are called upon if the crime involves finding a body. The roles specifically relating to examining remains or murders are:
- Forensic pathologist: the person responsible for examining the body, undertaking autopsies to determine cause of death and collecting any evidence that can be found on or in the victim.
They might also examine living victims to determine the cause and age of injuries received during the crime.
They use autopsy reports, police reports, medical records, suspect or witness interviews and the results of crime lab evidence analyses in the pursuit of answers.
- Forensic anthropologist: the person called in for cases in which remains are skeletal or difficult to identify.
These experts use skeletal remains to work out the age, sex and race of the deceased.
They can also identify any injuries or illnesses the victim may have suffered, and can sometimes even establish the time of death.
Forensic anthropologists can also perform toxicological, chemical and DNA tests on remains to discover more about the victim.
They can also find out a lot by visiting the location where the remains were found.
- Forensic odontologist: these experts are basically forensic dentists, who help to identify bodies by matching dental patterns with dental records collected from dentists.
They are also called in for cases in which bite marks or teeth are found.
- Forensic entomologist: these experts use their knowledge of insect life cycles to determine time of death.
It’s common for bodies that have been found sometime after death to be invaded by insects.
Forensic entomologists can also use their knowledge of where different insects live to work out if a body has been moved or not.
Observational skills are important for all forensic scientists, of course, as is the ability to be methodical and accurate at all times.
Scepticism is another important quality, particularly when investigating crimes. There are a couple of key things to remember:
Everyone is a suspect until something concrete proves otherwise, and witness accounts aren’t always accurate.
When referring to memories (such as during a witness account) most people have trouble getting all details correct and perceptions can be influenced by their personal lives and values.
A witness may state they saw a woman leaving the crime scene. But what if it was a man with long brown hair?
Variations on this easily-made mistake are endless and could lead to all sorts of complications.
It’s the forensic scientist’s job to make sure it doesn’t – to get the job done, and done correctly.
This is part one of The Conversation’s Forensics Australia series. Meet the people behind the science in parts two to five.Comment on this article
Ian Dadour receives funding from UWA.
University of Western Australia provides funding as a founding partner of The Conversation AU.