Why do forensic medicine experts fear climate change?

Writer: Salma Arafa - Translator: Amira Gawdat
الثلاثاء 02 ابريل 2024 | 06:43 مساءً

In summer of 1959, specifically in June 11 of the same year, the Police found a corpse of a Canadian girl who is about 12 years old after two days of her disappearance in one of the woods. They discovered she was murdered after being raped.

The finger of blame points to her schoolmate, “Stephen Truscott”, who is two years older than her, especially since he was seen taking her on his bike to an intersection before she disappeared.

Investigations by the Canadian authorities ended with “Truscott” being convicted of the horrific crime, and he was sentenced to death, before his sentence was commuted to life imprisonment. He was then released on conditional release in 1969, but the shame of being accused of sexually assaulting and killing a childhood friend continued to haunt him, despite his living among the people under a different name.

“Truscott” sought to overturn the conviction for nearly half a century, until he succeeded in 2007 after new evidence emerged, including a group of annoying insects.

Two forensic entomologists proved that forensic workers were wrong in determining the timing of death, which was based on examining the victim’s stomach at that time, only to discover that the victim had passed away far after the predetermined time, according to ABC News.

The case files included many photos of the crime scene, in addition to a description of the insects that gathered around the victim’s body as soon as she took her last breath. By measuring the larvae laid by these insects, and calculating the time it takes to grow to this degree, the timing of death was confirmed again.

What about the Arabs?

Interest in forensic entomology in the Arab world has increased in recent years. For example, years ago, Dubai Police began cooperating with a research team led by “Jeffrey Wells”, professor of biological sciences at Florida International University, to prepare a database of insects that could be used in investigations, and the emirate has already succeeded in solving a large number of witnessed crimes.

But it seems that climate change will not spare these creatures, which for many years have helped investigators uncover the mysteries of various types of crimes, most notably murders.

The rise in global temperature resulting from global warming is changing the distribution map of insects, including blow flies, which are one of the most popular species used by forensic experts. They have begun to change their locations in search of cooler climates, according to the Popular Science website.

Changes in the locations of these species may confuse the calculations of those working in the field, which may be surprised by new species whose activities are not proceeding at the pace they are used to.

Years ago, researchers at Indiana, the American University, observed the appearance of the "Lucilia cuprina" fly in Indiana State for the first time away from its original habitat in the southern states. Although it is very similar to the fly “Lucilia sericata", each of them follows a different schedule if they find a dead body.

The larvae produced by the newcomer do not grow as quickly as the larvae of their counterparts. Then specialists must be aware of any developments, so that they would not mistake determining the date of the crime when the types are similar.

Researcher “Christine Pickard” said, in previous statements, that an error in distinguishing between the two flies could lead to an overestimation of the date of death by a difference of 25%, according to the WFYI Indiana website.

Heat controls

In one of her papers, “Dr. Deborah Waller”, assistant professor in the Department of Biological Sciences at Old Dominion University and specialist in forensic entomology, says that “blowflies” are often among the species that reach first to the corpse, begin laying their eggs, and produce larvae that will go through three stages, but the time they spend in each stage depends on the temperature. Therefore, knowledge of the environmental factors in the area was included among the procedures that workers must know when beginning to examine the crime scene.

Regarding the impact of climate change, “Waller” noted in her interview with “Green in Arabic” that temperature affects most of the vital aspects of insects, such as geographical distribution, the selection of their precise habitats, growth and feeding rates, the timing of reproduction and egg laying.

In her view, all insect species will be affected by heat, but changes in the species most important to crime solving, carrion flies and beetles, will have the greatest impact on specialization of forensics.

“Waller” added that the stages that insects go through when arriving at a corpse will proceed at a faster pace due to the heat, and will take shorter periods. If the matter goes in one direction, and the temperature remains constantly high, it is possible to recalculate the period required for each stage. But, what if things do not go this way?

The American lecturer answers that the variability of the atmosphere due to heat waves will require more research to predict the duration of each stage under different conditions.

Perpetrators may also be fortunate if a natural disaster occurs in the crime zone. In “Waller's” point of view, floods and wildfires can kill or remove carrion-eating insects, as well as erase any trace of their activities. But, sometimes larvae may be found inside the submerged corpse of the murdered person before the water could reach it.

She also addressed the methods of preserving forensic evidence, emphasizing the prevalence of methods of digital storage that she believed should be used in addition to traditional preservation.

More than a decade ago, New York State authorities were in trouble after the floods caused by Hurricane Sandy destroyed two warehouses containing forensic evidence related to crimes being investigated by the authorities, which included weapons, DNA evidence, and cars.

The ABC 30 news website reported at the time that there were no precautionary measures to protect those evidences inside the warehouses, as they were contaminated with the water that reached them.

As for the future of forensic entomology, “Waller” believes that there are a huge number of questions that must be answered, and a large number of researches that must be conducted to keep pace with the changing climate that cannot be predicted. But, she stressed that “specialists in forensic entomology love the challenge".