Entomologists and doctors research death
Time of death, the cause, and the potential culprits of a murder – this is just part of the information gathered by forensic entomologists from the University of Wrocław. Their scientific work with colleagues from the Wrocław Medical University has given rise to establishment of the Forensic Biology and Entomology Laboratory, within the Department of Invertebrate Biology, Evolution and Conservation at the Faculty of Biological Sciences of the University of Wrocław.
In a nutshell: forensic entomology utilises our knowledge of insects – their biology and ecology – for the purposes of court proceedings, including investigations and legal processes. This is an interdisciplinary field including law, forensic medicine, chemistry (toxicology) and biology (entomology, genetics). Most often, it is associated with the medical-criminal field, that is, with prosecution proceedings.
“As forensic entomologists, we focus on researching and describing the development models of insects associated with particular phases of decomposition of corpses, in various conditions,” said Professor Marcin Kadej, the Head of the Forensic Biology and Entomology Laboratory.
The work Kadej describes is necessary for a better understanding of regularities in insects’ development in corpses, the interactions between the two, and their influence on decomposition. The arduous work done by forensic entomologists provides us with knowledge that helps determine whether the body was moved, answers questions about the cause of death, identifies the suspects, detects toxins and drugs, and recognises the DNA of the perpetrator or victim.
“The forensic entomologist’s task is to identify insects at different stages of their life cycle, such as eggs, larvae and mature insects,” says Kadej. “Our main goal is to determine the time of death based on qualitative and quantitative analysis of the insects found on the corpse, particularly when the use of other methods of forensic medicine is difficult or impossible to implement.”
The most important species in forensic entomology are those classified as necrophages (organisms feeding on dead organic matter). Two orders of insects are particularly important: flies (e.g. calliphoridae, muscidae, sarcophagae, piophilidae, phoridae), and beetles (e.g. silphidae, dermestidae, histeridae, staphylinidae and cleridae). We also need to appreciate the importance of insects from other ecological groups, such as predators, parasitoids, parasites and other insects, which appear on dead bodies by chance.
“A human corpse is a very convenient habitat, in which part or whole of the insects’ life cycle takes place,” said Marcin Kadej.
Forensic entomologists usually work alone in their laboratories, far from publicity; they search for facts based on biological clues obtained from the scene, such as different insects, their remains or traces of their activity, including blood stains and excrement. The scientists are bound by secrecy for the duration of the investigation. Violation of this secrecy is punishable by law, which is why we rarely read about the spectacular twists and turns of court proceedings contributed to by these specialists. Yet, the knowledge of entomologists often contributes to determining the PMI (post mortem intervallum – the time from death to the finding of the body), and helps specify where the crime could have been committed, and often even to identify the perpetrator.
The Forensic Biology and Entomology Laboratory at the University of Wrocław conducts research on the distribution and bionomy of necrophagic insects and other invertebrates. Its researchers work, amongst other things, on preparing expert opinions for the purposes of initial criminal investigations and court proceedings. They also work on preparing their successors.
“The combination of taxonomic knowledge with some aspects of forensic entomology allows us to offer the students of the Biological Sciences Department, and the Chemistry Department, training in a very peculiar subject. That is, forensic entomology. The course allows them to learn the methodology and obtain practical skills,” explains Prof. Kadej.
Students can draw on the rich experience of the team, who regularly work with Polish and foreign specialists. For two years now, they have also been participating (with their colleagues from the Department and Faculty of Forensic Medicine of Wrocław Medical University, under the supervision of professor Tomasz Jurek), in autopsies, securing and investigating biological traces on corpses.
“Our work with forensic doctors is of immense importance, because it not only allows us to exchange experiences, but also to conduct research together. This in turn prepares the ground for scientific papers, which can deepen our knowledge in the field of broadly understood forensic science,” said Prof. Kadej. “The first spectacular effect of our well-developing work together was an article that was widely-commented upon all over the world, describing the first case of honey bee, common wasp and red squirrel nesting in a mummified human corpse, which had been hanging from a tree for 13 years. The article was published last year in the prestigious ‘Forensic Science International’.
“Having noticed both the scientific potential of my own findings as well as my own limitations, during one autopsy I asked the biologists from the University of Wrocław, Professor Dariusz Tarnawski and Prof. Marcin Kadej, for help,” said Dr. Łukasz Szleszkowski from the Wrocław Medical University.
Szleszkowski, the head of the Forensic Thanatology Department, is engaged in research and educational works at the Medical University, produces court statements for the legal authorities and administration of justice as a medical assessor, and supervises the work of the autopsy department at which autopsies ordered by the prosecution are performed. He works in so-called traditional forensic science, performing autopsies (for example, in murder cases), with corpses undergoing post-mortem changes that require identification, exhumation, etc. Since 2011 Dr. Szleszkowski has been working with the Institute of National Remembrance, where together with anthropologist Agata Thannhäuser, he takes part in searching for and exhuming victims of totalitarian systems in Poland and abroad. Together they have investigated the remains buried at the ‘Łączka’ in Warsaw, on the premises of KL Gross Rossen, and in the mass graves of Polish partisan troops discovered in Opole, Silesia and many other places. The work with the biologists from the University of Wrocław is one more field in which Szleszkowski can use his skills and immense experience – and he is expanding his knowledge constantly. “After the success of our publication we came to the conclusion that forensic entomology has great scientific potential that will allow for development of other branches of forensic science,” explains Dr. Szleszkowski. “I used to seriously consider studying biology, so this combination of professional work with my old interests was particularly tempting. In the course of our work together I’ve been trying to make use of Marcin’s knowledge to broaden my own horizons.”
“The scientific potential of some cases requires further research and continuation of our work together,” Szleszkowski added. “And since we soon found common ground with Marcin, we soon began developing plans for further work together. It came to us rather spontaneously and naturally. You could say we’re on the same wavelength.” Soon after, these two scientists from different fields joined forces, with an idea to establish the Forensic Biology and Entomology Laboratory.
“This is Marcin’s brainchild and original idea,” said Dr. Szleszkowski. “Our long conversations over the autopsy table and outside the mortuary surely strengthened the belief that the University of Wrocław should establish a new laboratory, which could be a formal stepping stone between the two universities. We obviously supported him in all his endeavours, because we saw the enormous potential such a laboratory has for our research-educational facilities.”
This ‘stepping stone’ is a key term here. Dr. Szleszkowski highlights the fact that forensic medicine itself is an interdisciplinary field, joining medicine and law, but one also touching on other fields of science. He thought that establishing the time of death based on the developmental stages of insects greatly exceeded the abilities of a forensic doctor.
“To be honest, I thought I could, to some extent, analyse entomological data, until I took part in the first lecture by Marcin at a conference of the Polish Forensic Association. I’m glad that he quickly proved me wrong because it’s an absolute must to have expert knowledge of invertebrate biology, and entomology,” said Szleszkowski.
He also admits that working with the entomologists taught him to describe the entomological traces on corpses and how to secure them. Not long ago, such terms as ‘pupae’, ‘puparium’ and ‘frass’ were completely unknown to him. Now, though, during autopsies of corpses scavenged by insects, his team is accompanied by Marcin Kadej, who secures the samples.
“Science today is all about interdisciplinarity, and I think our work together perfectly suits this trend, particularly because there is still a lot to be done in the field of forensic entomology in Poland,” says Szleszkowski.
They still have many plans to pursue, have already prepared a new paper, and have many ideas they want to realise in the coming years. They also both work with students. This year, Dr. Szleszkowski had a lecture at the University of Wrocław as part of a course entitled ‘Forensic Entomology’. Students at the University of Wrocław participated in forensic autopsy at the Faculty and Department of Forensic Science of the Wrocław Medical University. This allowed them to see the secrets of the specialists from forensic science in practice.