Insect secrets that can put killers, rapists behind bars
Sensing danger, the Madagascar hissing cockroach flexes its body and exhales air, emitting an angry shrill as Kirsten Williams deftly handles the credit-card-sized insect with the kind of ease that a policeman shows in handling a gun.
For most people, flies, maggots and cockroaches are nothing more than gross annoyances — but for elite detectives and scientists, like the Durban entomologist, they know that evidence gathered from insects could be the difference between rapists, murderers and poachers walking free or doing jail time.
Williams, who keeps a tank of the roaches in her office, recently delivered a talk on how ordinary houseflies are a valuable crime-fighting tool. The bugs are unwitting witnesses to some of the country's most heinous crimes, with forensic entomologists using insects to trace criminals in more than 100 cases in South Africa in the past five years.
"We look for insects that feed on decaying corpses. Flies are most important in the beginning because they are the first to arrive. Then we look for the beetles which feed on the dried remains," Williams said."Flies can smell decomposition from several kilometres away. When they arrive they lay eggs and when the maggots hatch we can plot a timeline. You measure the length of the maggot and that gives an indication of its age. We are doing research on maggot growth in the lab and seeing how temperature affects their development," Williams said.
Police spokesman Brigadier Vish Naidoo said that while entomologists were not employed in every murder case, they were a valuable addition to a detective's toolkit. "There were murder cases, one in Marikana and another in Huhudi, where entomology assisted with determining the possible time of the murders," he said.
"The police have invested a lot in promoting the services of the forensic entomologists, and in all the provinces crime-scene investigation members have been trained to assist with the collection of forensic entomology specimens," Naidoo added.
These specimens, silent witnesses, have proven vital in cracking several high-profile cases, including fingering Donovan Moodley for the murder of Leigh Matthews and putting serial killer Moses Sithole (see sidebar) behind bars. They have also been used in rhino-poaching cases.
Mervyn Mansell, a retired entomologist, frequently consulted with the police on various cases. When he arrived at a crime scene, it was not the smoking gun he looked for, but flies, maggots and beetles.
For him, these insects and their eggs are crucial, giving detectives an idea of how a murdered person's final moments may have played out. They could be as important as DNA, or even fingerprints, he said.
"We determine the age of the maggots and use this to extrapolate back to the time of death or exposure. This is especially accurate in victims where blood is present, as adult flies of certain species are strongly attracted to the scent of blood," said Mansell.
The veteran entomologist said that the police had two officers who were dedicated to entomology...