HEALTH: Blood Pattern Analysis
Even a tiny drop of blood at the scene of a violent crime can give important information to the police. Blood is there either because it has dripped out1 of a small wound, sprayed out from an artery, oozed out2 through a large wound, or flown off a weapon. Using blood pattern analysis, police can learn a lot about what happened from the shape of the blood drops.
Sometimes a murderer cleans the crime scene very carefully, and if detectives cannot see any blood they spray a chemical called Luminol across the scene. This makes it possible to see the blood in the dark. Luminol can show up3 very small drops of blood.
From blood at the scene of a crime, police can learn about the person the blood came from. They can tell the person’s blood type and, because male and female blood cells are different, they can also work out4 if the blood comes from a man or woman. Also, 80% of us are ‘secretors’, which means our blood type is contained in other bodily fluids. This can also help identify suspects.
In 1984 a man, Graham Backhouse, was found injured near his home with deep cuts across his face and chest. A neighbour lay dead nearby. Backhouse said the neighbour attacked him, and so he shot the neighbour to defend himself. But the shape of the blood drops showed that Backhouse was standing still when he was wounded, and there was also no blood from Backhouse on his gun or near the victim. Police were sure Backhouse shot his victim and then wounded himself. He was found guilty of murder.
Com base no texto, as expressões numeradas apresentam os seguintes significados:
