Cambridge & Great Eastern Regional Group

SCI Members' News

Using forensics to finger the criminals

Carolyn Morton from the University of the West of England treated the Cambridge and Great Eastern Regional Group to a morbidly fascinating talk on forensic science in early December.

Forensic science can be simply defined as the application of science to the law. In criminal cases forensic scientists are often involved in the search for and examination of physical traces which might be useful for establishing or excluding an association between someone suspected of committing a crime and the scene of the crime or victim. Such traces include blood and other body fluids, hairs, textile fibres from clothing, materials used in buildings such as paint and glass, footwear, tool and tyre marks and flammable substances used to start fires.

Sometimes, the scientist will visit the scene itself to advise on the likely sequence of events or any indicators as to who the perpetrator might be, and to join in the initial search for evidence. Other forensic scientists analyse suspected drugs of abuse, specimens from people thought to have taken them or to have been driving after drinking too much alcohol, or to have been poisoned. Yet others specialise in firearms, explosives, or documents whose authenticity is questioned.

Reliability
The importance of properly conducted, rigorously checked and reviewed scientific evidence is paramount. The quality and reliability of scientific evidence compares extremely well with traditional forms of evidence, such as eyewitness accounts or confessions, both of which can be extremely misleading.

With gruesome examples, Morton explained how bloodstain patterns produced during crimes can provide valuable evidence. Bloodstain pattern analysis has been crucial in solving several high-profile criminal cases. Apparently the splash marks of droplets of blood produced during violent struggles create a characteristic pattern resembling an exclamation mark.

She explained the importance of footwear print and fingerprint analysis, as well as giving us an insight into genetic profiling (which she stressed should not be called DNA fingerprinting). Genetic profile databases have become increasingly important. The National DNA Database (NDNAD) matches DNA samples from scenes of crime – for example from blood or semen – with individuals or other crimes. The NDNAD now holds three million profiles. This has been used to solve many totally unrelated crimes, sometimes perpetrated decades ago. Modern techniques can also be used to obtain somewhat equivocal information on ethnicity.

Genetic profiling
The unexpected twists and turns of criminal investigations were illustrated by the story of the first use of mass screening using genetic profiling, a technique developed by Alec Jeffreys at Leicester University, UK. This investigation took place in Leicestershire in 1986–1987, in the case of two murders. The police had one suspect, Richard Buckland, who had confessed to only one of the murders, but the genetic profiling evidence conclusively demonstrated that he was not the culprit. Buckland became the first person in the world to be exonerated of murder through the use of DNA profiling. Jeffreys said: ‘I have no doubt whatsoever that he would have been found guilty had it not been for DNA evidence.’

The mass screening of 5000 local men did not identify the killer. However, the investigation took a strange twist when a year later a woman overheard a colleague bragging that he had given his sample whilst masquerading as his friend, Colin Pitchfork. Pitchfork, a local baker, had apparently persuaded him to take the test for him. Pitchfork was subsequently arrested and his DNA profile was found to match with samples from the murders. He was sentenced to life imprisonment for the two murders in 1988.

John Wilkins
CaGE Regional Group