Flesh flies and crime scene investigation

The work of a forensic entomologist at a crime scene is often imperative in solving the crime, but this is being ignored by the police. This is according to forensic entomologist Professor Theuns van der Linde, who presented a paper at the International Congress of Entomology in Durban on Friday. Van der Linde, one of only two forensic entomologists in the country, said police did not call him to crime scenes. "I am meant to work with the police, but often I only hear that a body has been found when I get a call from my friend who transports bodies to the mortuary." He said there was an apathetic attitude towards the assistance forensic entomologists could provide.

"There are officers who recognise that I can help. But some feel there is no need for me. The other problem is that they want to leave a crime scene quickly. If they call me, they will have to hang around for an hour longer while I do my work." Van der Linde said forensic entomologists used the insects on a body to determine the time of death. "By looking at the life stages of the insects that are found on the body, we can determine the post mortem interval, in other words when the body was dumped there and when the person was killed." He said the insects most commonly found on dead bodies were different species of blowflies and flesh flies. Blowflies would rest on a corpse and lay eggs. The eggs would hatch within eight hours and turn into maggots. The maggots and flies would feed on the dead tissue. Flesh flies would arrive on the body slightly later than blowflies but would give birth to larvae rather than eggs. Van der Linde said it was imperative that the entomologist should be at the scene to gather evidence. "If I am not at the scene I have to rely on information from the autopsy. But often many things can happen from when the body is found until the autopsy is done. Also for my work, the weather, position of the body and the insect specimens at the scene are important." One of the case studies Van der Linde presented on Thursday involved the murder of a young woman in Bloemfontein in 2001. The woman went missing on New Year's Eve and the main suspect pointed out her body 13 days later.

According to the level of decomposition, Van der Linde expected certain types of insect on the body but found something else. "I did not go to that crime scene, so I had to rely on the autopsy report. When I saw that there were only larvae on the body, I knew something was wrong. The insects should have been in a more advanced life stage if the body had been in the field for almost two weeks." Van der Linde suspected the woman might have been killed later, or the body had been hidden after the murder. He then spoke to the investigating officer and discovered that the body had been found covered in a duvet. He then simulated the crime scene conditions using two pigs. "I covered one in a duvet and left one exposed and found that after day 12 there were still only larvae on the pig that had been covered. "The larvae had not developed to the next stage. Therefore I concluded that the woman was killed on New Year's Eve and dumped on the first or second of January.

"I had to go the long way around to establish the truth (of what the suspect told police); it would have been much faster if I had been at the scene." National police spokespersonn Senior Superintendent Lindela Mashigo said the police would be able to discuss the relationship between forensic entomologists and police only on Friday. Source: The Mercury http://www.themercury.co.za.

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