Crime Scene Investigation - "Seeing is believing"

Article taken from Issue 2 of the Forensic Access Newsletter "Benchmark"

There is a tendency to believe that there is not much point asking a forensic scientist to visit an assault crime scene, months after the event, since it might be safe to assume that everything remotely of interest will long since have been cleaned up, or removed for detailed examination. But this is far from true.

Quite apart from providing the scientist with a knowledge of the essential geography of the place, and which can be critical to determining whether physically something could have happened, specific clues may remain which might not have been noticed initially. The presence or absence of these assume increasing importance as issues between prosecution and defence become crystallized.

Take, for example, the case of the woman charged with the deliberate and cold-blooded murder of her mother, whose body had been found some months later hidden in the house they had shared.

The woman claimed a history of abuse by her mother which culminated one day with her striking her mother with a blunt instrument in the heat of the moment. But matters took a turn for the worse when the police scientist discovered what he thought could be stab cuts in the jumper the mother had been wearing and which was still on her putrefying body when it was found.

However, our close scrutiny of the damage suggested that this was probably simply due to the insect life that had infested the body after death. Moreover, and this is the point of the story, our inspection of the scene revealed a pattern of very fine blood spots - characteristic of blunt assaults, at around about the position the daughter said the only blows had been struck. She pleaded guilty to manslaughter on the grounds of diminished responsibility, and this was accepted by the court.

Another case involved a man charged with attacking a friend who had come to visit him at his flat. The two men had been drinking together when the friend claimed that he was suddenly set upon by his host who struck him several times on the head with a hammer. With blood pouring from head wounds, he had managed to escape to the street outside where he collapsed on the pavement.

The defendant denied all involvement in this. Instead he said his friend had been drunk and had fallen down some steps in the hallway at the premises. The friend had picked himself up and walked out.

In this case matters were confused by vomit staining on several walls of the flat and which was contaminated with small amounts of blood - some of it in the form of tiny discrete spots. This reflected a medical condition from which the defendant suffered and which apparently causes frequent projectile vomiting.

But, arguably, of much greater significance here was a pattern of small blood spots which we found low down on the walls where the defendant said his friend fell, and the complete absence of any blood at the site of the alleged attack or, indeed, anywhere else on the route out into the street. This suggested that there might be no case to answer, and the court apparently agreed.

These represent two cases which looked fairly unpromising at the outset, but which a visit to the scene - long after the event, helped to resolve. They also underscore the need for forensic biologists to have strong stomachs, but that is another matter.