The blood detectives: Scientific breakthrough in reading stains may help solve crimes

A camera that can detect and date blood traces is set to revolutionise the science of crime scene investigation.

Long considered the “holy grail” by forensic experts, a new hyperspectral imaging device that can scan for the visible spectrum of haemoglobin could dramatically speed up police inquires, lead to more convictions and reduce the number of miscarriages of justice, its creators have claimed.

A prototype built by researchers at Teesside University has demonstrated extraordinary levels of laboratory accuracy.

Month-old blood samples can be dated to within a day, while fresh traces have been pinpointed to within an hour of their being taken, potentially helping police to establish a time of death immediately – a process which at present can take several days – and allowing detectives to build a more rapid chronology of events.

Blood samples and splatter patterns are one of the most commonly used forms of prosecution evidence in cases of violent crime.

It is believed the technology could also be applied to other fluids, including sweat, saliva and semen, which could also improve conviction rates for rapes and other sexual assaults.

Dr Meez Islam, a physical chemist and reader in the University’s School of Science and Engineering, who led the team working on the project, said that identifying bloodstains often posed serious problems. Forensic teams were still working with techniques devised a century ago, and there was currently no effective way of dating blood.

“Often you go to crime scenes and what appears to be blood isn’t blood. Blood on dark backgrounds can be hard to see and there are traces of blood that are not visible to the naked eye. What this does is provide fast, at-the-scene identification of blood and speed up the investigative process, as items do not need to go back to a laboratory to be examined. To use hyperspectral imaging in a way that scans the crime scene for blood also means that the chances of missing a bloodstain are vastly reduced,” he said.

The new technology, which will be unveiled at a forensic science conference in Manchester next month, uses a liquid-crystal tunable filter and is able to offer immediate results. The filter works by isolating different wavelength bands of colour, so that it can detect blood against other similar-looking substances or in hard-to spot locations such as on red clothing, carpets or furniture.

Because blood changes colour over time, from bright red to muddy brown, at a known rate, the device is able to put an accurate age to a sample. At present, forensic scientists must paint on chemicals to areas where they believe blood may be present hoping to produce a luminous or other reaction with iron found in haemoglobin. It is a procedure routinely demonstrated in television dramas such as CSI: Crime Scene Investigation.

But failure to locate samples has plagued a number of high profile cases. In the investigation into the murder in 1993 of the teenager Stephen Lawrence, detectives were hamstrung by their inability to find any physical evidence linking the suspects to the killing.

It was only during exhaustive laboratory re-testing during a cold case review that a spot of Stephen’s blood was found on the seam of the collar of a jacket belonging to his killer, Gary Dobson. In the case of the south London schoolboy Damilola Taylor, murdered in 2000, experts missed a bloodstain on a trainer belonging to one of his killers.

At Teesside, which is marking 21 years since it became the first university to train graduates in forensic and crime scene courses, researchers believe the breakthrough could help to prevent a repeat of the blunders.

Dr Islam said there has been interest in the innovation by police forces and he needs £100,000 to create a working model. “This is a fairly small investment for a relatively large societal impact. This could help reduce crime, stop the wrong people being convicted and make sure the right people go to jail,” he said.

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