Stain-spot­ting a snap

Weekend Argus (Saturday Edition) - - MEDIA& MARKETING - JONATHAN BROWN

A CAM­ERA that can de­tect and date blood traces is set to rev­o­lu­tionise crime scene in­ves­ti­ga­tions.

A new hy­per­spec­tral imaging de­vice that can scan for the vis­i­ble spec­trum of haemoglobin could 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’s be­lieved the tech­nol­ogy could also be ap­plied to other flu­ids in­clud­ing sweat, saliva and se­men, which could im­prove con­vic­tion rates for rape and other sex­ual as­sault.

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 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 at-the-scene iden­ti­fi­ca­tion of blood and speeds 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 vastly re­duces the chances of miss­ing a blood­stain,” he said.

The new tech­nol­ogy, to 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 it can de­tect blood against other sim­i­lar­look­ing 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 chem­i­cals on to ar­eas where they be­lieve blood may be present, hop­ing to pro­duce a re­ac­tion with iron found in haemoglobin. It is a pro­ce­dure demon­strated in TV dra­mas such as CSI.

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 retest­ing 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 tackie be­long­ing to one of his killers.

Is­lam said he needs £100 000 (R1.6 mil­lion) to cre­ate a work­ing model. “This is a fairly small in­vest­ment for a rel­a­tively large so­ci­etal im­pact,” he said. – The In­de­pen­dent on Sun­day

A BET­TER PIC­TURE: New blood cam­era will help foren­sic ex­perts.

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