Posted: Friday, 30th September 2011
A TEAM of chemists is shedding new light on crime scene investigations by being the first to investigate the effects of prescribed drugs on blood spatter patterns.
Blood pattern analysis (BPA) is one of the cornerstones of forensic police investigations of violent crimes and deaths, giving detectives vital clues about events and assailants.
But accepted formulae for the behaviour of blood do not take into account the effects of medical drugs in the bloodstream, according to Meerna El-Sayed, Dale Brownson and Craig Banks, of the School of Science and the Environment.
The team looked at the effects of warfarin - a standard treatment for thrombosis – and at cases in which misinterpretation of blood pattern analysis may have occurred.
Meerna (pictured) said: “Around 2 million people in North America alone take warfarin as an anticoagulant, so its effects are widespread. We measured the changes in viscosity, surface tension and density of blood through the presence of levels of warfarin, from therapeutic to fatal dose, and found the differences were up to 5% in tension and 20% in viscosity.
“When incorporating this into previous equations, it appeared that the parameter affected by warfarin use could cause a variation of up to 6% in final bloodstain diameter.
“This variation could have implications in the interpretation of blood stains and therefore crime scene reconstruction.”
The team, who published their results in the journal Analytical Methods, conclude: “We hope that academics and CSIs consider the implications of medicinal drugs on BPA and on the reliability of evidence in investigations and legal proceedings.”
Meerna, who earned her first degree in the School is the University’s first PhD student in forensic science.