Mastodon Scientific Frontline: When maggots uncover a murder

Tuesday, March 29, 2022

When maggots uncover a murder

These maggots belong to the latrine fly. They are quasi criminal officers.
Credit: Roberto Schirdewahn

Investigators still have to go in search of traces. But if they find crawling animals at the scene, they can be of great help to them.

First come the blowflies. A few hours after death, they control the eyes, nose, mouth and wounds of a lifeless body. Here they lay their eggs - and just a few days later it is teeming with life: numerous maggots hatch and feed on the dead tissue until they finally become new flies. Not only gliding, other types of flies join in over time, and finally various beetles are crawled on. The hustle and bustle that takes place on corpses can be quite revealing - for example, if you want to find out when and under what circumstances a person died.

With these questions, Dr. Ersin Karapazarlioglu is only too good. He conducts research in the RUB Faculty of Biology and Biotechnology in the Prof. Dr. Wolfgang Kirchner. Before coming to Germany in 2020, he worked for 17 years in Turkey as a criminal officer and as a lecturer at the police college and a university. He always looked for insects at crime scenes. With their help, he was able to determine the time of death of a body more precisely than with other methods. The method is called forensic entomology. The method was initially established in the USA and is still in its infancy in Europe.

Established in the USA, data is missing in Europe

Knowledge from the USA cannot be transferred to Europe simply because there are different types of insects in different geographical regions and their development depends on many environmental factors. Research is needed on site in Europe in order to be able to determine the time of death of a body with the help of insects. Ersin Karapazarlioglu would like to lay the foundations for this at the RUB. As part of Wolfgang Kirchner's team, he conducts research as part of the Philipp Schwartz initiative, a grant for vulnerable scientists who had to leave their homes.

Ersin Karapazarlioglu worked as a criminal officer in Turkey for many years. Today, with his research, he is helping to establish methods that criminal officials could help with their forensic work in the future.
Credit: Roberto Schirdewahn

In 2015, the Alexander von Humboldt Foundation and the Federal Foreign Office launched the Philipp Schwartz Initiative. It enables researchers who can no longer work in their home country because they are threatened or persecuted to continue their work at German universities and research institutions. Three fellows are currently researching at the RUB as part of the program in biology, history and psychology. Another fellow in geography will be added soon. The RUB Scholars at Risk program is centrally managed by the RUB International Office. In addition to the Philipp Schwartz initiative, it also includes the Scholars at Risk Advocacy Seminar, in which students campaign for wrongly detained scientists worldwide as part of human rights campaigns.

"There are two methods to determine the time of death using forensic entomology," explains Ersin Karapazarlioglu. “Either you look at the age of the maggots that you find on a body, or you look at the different types of insects at the scene.“These two methods provide insights on different time scales. The maggot age reveals the time of death a few days to a few weeks after the death; the insect composition can also be used months after death.

Behind it is the following: Certain types of flies lay their eggs in the tissue of a body just one to two hours after death. A few days later, maggots hatch, which grows bigger every day. If you find a maggot at a certain stage of development at a crime scene, you can conclude how many days it is old and thus when the eggs were laid - this corresponds approximately to the time of death.

This method works for about a month; then the maggots turned into flies and another method was needed. Species that are not quite as quick to find themselves at the crime scene as the flies, such as various beetles, which only appear at a later stage of decay, help here. The presence of certain species at the crime scene helps investigators to estimate how many weeks or months ago death was.

Environmental influences crucial

"But both methods depend heavily on environmental influences," says Karapazarlioglu. The temperature largely determines how fast the development cycle of a species takes place. The composition of the earth or moisture also has an influence. In addition, there are other insect species in the country than in the city - it is therefore important for criminals to include a lot of background information.

"After a murder, bodies are often buried to cover up the traces of the crime, but not particularly deeply."
Ersin Karapazarlioglu

Ersin Karapazarlioglu is currently researching which types of insects in Germany are involved in the process of decay over the seasons - and whether it makes a difference how deep a body is buried in the earth. "After a murder, bodies are often buried to cover up the traces of the crime, but not particularly deeply," he says. Therefore, the process of decay can be different from deep underground - so far, however, this has hardly been examined.

A self-constructed observation grave

Ersin Karapazarlioglu buried a sheep in a self-constructed observation grave. He can take samples from the ground using special devices.
Credit: Roberto Schirdewahn

In order to investigate the effects of superficial buriedness, Ersin Karapazarlioglu constructed a special observation grave. It is closed on one side with a plexiglass pane so that you can look inside. Devices are also attached in eight places with which the researcher can take samples of the earth and the organisms it contains. A sheep that comes from a slaughterhouse has been buried in the grave for several months.

In forensic entomology, sheep and pigs are used as model organisms because they have a body weight comparable to that of humans and the processes of decay are very similar to them. Before burying, the sheep are shaved in order to adapt the nature of the skin to that of humans.

"The idea of the observation grave is to have access to the animal without disturbing the process of decay," Karapazarlioglu explains his construction. For comparison, he did not bury another sheep, but exposed it to decay and infestation with insects on the surface. Every one to two days, Ersin Karapazarlioglu takes samples from both carcasses and compares the insect compositions. To do this, he has to determine the small animals under the microscope - because different species can often only be distinguished on the basis of tiny details.

"The results show that burying plays a role in the process of decay and insect colonization," summarizes the researcher. “We found other insect species on a carcass that is exposed to decay and insect colonization on the surface than on the buried carcass. "The number of colonizing insects on the surface was significantly larger than in depth. In addition, the surface degradation processes were much faster - it took ten days to reach the stage of decay, which only took place after 180 Days occurred.

Insect populations over the course of the season

The buried animal is exhumed regularly.
Credit: Roberto Schirdewahn

For a second study, Ersin Karapazarlioglu buried another sheep in summer 2021, which is exhumed once a month; he has already exposed the body six times. Each time he documents the animal's decomposition status and analyzes the insect activity. There are clear differences over the months: Due to the warmer temperatures, there are numerous insects in the grave in summer, and activity decreases significantly in winter.

"So far there have been only a few studies on insect fauna on buried bodies in Europe," says Karapazarlioglu. “We therefore hope that these experiments will provide valuable data for murder investigations."

Source/Credit: Ruhr University Bochum


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