ConsultantDr Andy WilliamsForensic scientist
A powerful counter of crime
Crime dramas have popularised the miracles of forensics and how it can help to convict even the most elusive criminal. From 3D restructuring to DNA analysis, forensics has become a key tool to help the police solve crimes.
The development of the technology involved has accelerated in recent years but the roots of forensic science go back a long way. So, how did we arrive at the powerful methods we have today?
Universal Images Group
The Ancient Greeks and Romans were the first to practise forensic science. The word forensic means 'in open court' in Latin.
The first sign of science being used to help solve a crime goes back to time of Archimedes. He had invented a method for determining the volume of an object. When the king of Syracuse suspected that a goldsmith had cheated him by replacing some of the gold in his new crown with silver, Archimedes was able to show that the gold had indeed been mixed with cheaper silver as it didn't weigh as much. Forensic science was born.Encyclopaedia Brittanica: Archimedes
Getty/ Photo 12
The first legally ordered autopsies were performed from 1302 in Bologna. This example was copied across Italy and Europe.
Doctor Bartolomeo da Varignana had been influenced by the Chinese book The Washing Away of Imputations or Wrongs, published in 1247. This helped pave the way for autopsies based upon scientific observations. Da Varignana examined the bodies of people who had died in suspicious circumstances to determine cause of death. However, his observations were limited by the power of the human eye and his tools.BBC: Leonardo da Vinci's anatomical sketches
Tomasino had no hemoptysis or haemorrhage... [He] died of dysentery... in the same way as many others have perished recently and do so all the time.
The invention of the microscope unlocked many new areas of forensic science. It enabled the discovery of red blood cells and spermatozoa.
Forensic investigators could now study tiny wounds, crystals or glass, and the characteristics of hair and fibres. Human remains were identified using teeth for the first time. Military surgeons produced vast bodies of work detailing wounds and causes of death. However, no matter how powerful the microscope, some causes of death remained undetectable.BBC History of the World: An early microscope
In 1832 chemistry was first used as evidence in a case of arsenic poisoning by sampling the lining of a victim’s stomach.
Before then, arsenic had been the perfect poison. It was undetectable and deadly in tiny doses. By the 18th Century it had earned the nickname ‘inheritance powder’. However, in 1832 chemist James Marsh designed a test for arsenic and used it to solve a murder case. The new science of toxicology was born and arsenic lost its appeal as the perfect murder weapon.BBC Magazine: 10 dangerous things in Victorian homes
I won’t be troubled long. He’ll go like all the rest of the Cottons.
The murder rate went up as gun crime became more prevalent. A development in bullet matching helped the police to trace gun owners.
In 1835 Scotland Yard traced a physical flaw in a bullet back to the mould and discovered the person who had bought it. Tiny flaws in bullets could be measured and matched to gun barrels. However, it was not until 1926 that this was used as evidence in court because of the difficulties in confirming identification. A new type of evidence was needed, which was permanent and accurate – photography was the answer.BBC News: Matching the gun to the crime
Mug shots and crime scene photography
Early photographs were time-consuming to set up, but investigators embraced them as a way of recording the exact circumstances of crimes.
This led to a boom in public involvement with cases – photographs were printed in newspapers with an appeal for information, raising the profile of forensic science. Later, French police clerk Alphonse Bertillon pioneered standard lighting, scale and angles for identification of criminals with face on and profile photographs. However, faces can look very similar. Another, more reliable method of identification was needed.BBC History: Gallery of Victorian mugshots
In 1892 the world’s first fingerprint bureau was established in Argentina after a well-publicised case where a bloody fingerprint identified a killer.
The uniqueness of fingerprints had long been suspected, but in 1892 Francis Galton calculated the chances of identical prints were one in 64 billion. Soon the British were using fingerprinting in India to identify retired soldiers so their relatives couldn't keep claiming their pension after their death. Fingerprinting soon became standard practice and is still being developed today, as scientists find ways to take prints from new surfaces.BBC News: Modern fingerprint analysis
Human ABO blood types were discovered in 1900 and were soon used to determine whether blood present at a crime scene matched a suspect or victim.
Arthur Conan Doyle wrote about Sherlock Holmes using blood analysis before it was possible in reality. Initially these tests were crude and gave inconclusive results in anything but the simplest cases. More blood markers were discovered and tests were developed to increase accuracy until it was found that blood was as unique as a fingerprint. However, as blood was required from a crime scene to perform the tests, forensic scientists needed other ways to link a suspect to a crime.BBC Future: Why do we have blood types?
The first forensic police laboratory was created in the attic above a court. This controlled environment led to an important discovery.
Edmond Locard's analysis of particles of dust led him to develop one of the fundamental principles of forensic science – a criminal will leave some trace on a crime scene, and take some trace away with them. He called this the principle of exchange. He used this powerful new technique to link suspects to a crime scene by examining hairs, fibres and dust. The core elements of modern forensics were established. These techniques improved until the next revolution – the discovery of DNA testing.Forensic Science Central: biography of Edmond Locard
Any action of an individual, and obviously, the violent actions of a crime, cannot occur without leaving a trace.
The discovery of DNA analysis – identifying anyone's unique biological code – revolutionised forensic science.
DNA replaced blood as the most powerful method of identification. It is invisible to the naked eye and detectable in traces left behind by all but the most careful criminals. Initially, courts had to wait weeks for results. It took 15 years before the result times were down to a couple of days. In 1996 a UK database of DNA was established, a powerful addition to fingerprint records. Since then, the predictive power of forensic science has been significantly improved using computer power.BBC Science: How does DNA testing work?
Computer graphics are now used to create compelling visual evidence to clarify the events of a crime for jurors.
3D reconstructions of crime scenes, traffic collisions and bullet trajectories are all used to solve crimes. However, animated reconstructions have been criticised as potentially misleading due to their persuasiveness. Older methods are still used and improved regularly, including magnetic fingerprinting and alternative light photography to see non-visible evidence. Forensic science will continue to develop the power of its techniques to deliver justice through logic and science.