How Do Insects Help in Criminal Investigation?


  • Insects play an important role in assisting the investigation process of various criminal cases. The development of forensic entomology research over several decades has made it one of the most accurate and precise methods for determining time of death.
  • Insect activity can be a reference for determining the time of death through the presence of colonies and the developmental stage of insects [maggots, for example] found on the victim's body.
  • A number of types of insects are often used in forensic entomology investigations, including green flies [Lucilia sp.], cheese skippers [Piophilidae], fleshflies [family Sarcophagidae] and so on.
  • Despite positive developments and improvements in this field , especially in the last 20 years, insects are still rarely considered as a tool in forensic cases.

Determining the time of death, investigating what happened to the body, is an important thing in the criminal case investigation process. And if we focus on insects, perhaps everything will be revealed. The question is, how can insects help investigate criminal cases?

This method is recorded as having been used since the 13th century in China, increasingly since the 19th century, and its value for forensic cases was only recognized in the early 20th century. Since then, decades of research have turned it into one of the most accurate and precise methods of determining time of death.

However, this process must be properly analyzed by an experienced and trained forensic entomologist. The aim is to provide an accurate estimate of the victim's time of death, sometimes the place, as well as other valuable information, including the cause of death [Joseph et al ., 2011].

Dr. Jason H. Byrd, a forensic entomology expert from the University of Florida, said that in forensic investigations, the study of insects and their arthropod relatives even applies to uncovering civil and criminal legal issues.

"There are various types of forensic entomology experts out there who are trying to find insects to help investigate criminal cases or murders in their cities," he said, in the Airlangga Veterinary Forensics Summer Course [AVFSC] webinar entitled  Wildlife Veterinary Forensics For Balancing The World , some last time.

He explained that to uncover and determine the estimated time of death in a number of cases, police officers, detective agencies and forensic entomologists tried to find insects around the victim's body.

"Insect activity can be a reference for determining the time of death of the victim through the presence of colonies and the developmental stage of the insects found on the victim's body," he continued.
A number of types of insects are often used in forensic entomology investigations, including green flies [ Lucilia sp .], cheese skippers [ Piophilidae ], fleshflies [ Sarcophagidae family ] and so on.

So far, although there are many insects involved in the process of decomposing the human body, flies are among the insects that are often used in uncovering criminal cases.

"This is because, during their life phase, insects such as green flies will hatch their eggs into the victim's body, so that when the eggs hatch into maggots, they will attach to parts of the victim's body to get nutrition and grow," said Jason.

Information about the size and age of fly larvae on corpses can be used to identify the time, and sometimes place, of death.

"However, because there are so many fly families, they must be identified first before carrying out further investigation processes."
Forensic entomology

In general, forensic entomology is often used to estimate time of death, especially for victims who have been dead for a long time [up to one month], which is difficult to investigate by general forensic science.

This timing is achieved through a process known as the minimum postmortem interval [PIM]. Namely, the time since the first insect colonization, by determining the age of the insect stages [maggots] that develop on human remains and analyzing the successive patterns, pre-emergence, arrival, residence, and departure of insects from the victim's body.

Citing research by Lutz et al . [2021], it can be applied to more fields as well as answer a number of important questions, such as a valuable indicator of whether the body was moved? Or also, manipulation of the crime scene.

“In addition, larvae and pupae, more precisely their gut contents and tissues, hold promising information for the investigation of sexual crimes, especially when victims are found in advanced stages of decomposition.”

This also applies to genotyping human DNA, in an effort to identify the sources they ate, or to detect drugs consumed by a deceased person during life.

“Finally, as climate change occurs and the spread of invasive species becomes more widespread, insect infestations on living humans will occur more frequently. "In fact, in the Northern Hemisphere and can be evaluated by analyzing the patient's [pet] fauna, to determine the period of neglect, to clarify the question of responsibility regarding negligence," he continued.

Citing Durden & Mullen [2002], careful examination of collected insect evidence can also help solve other crimes [for example, the origin of drug shipments, the source of vehicles, as well as other accessories used in crimes] by having arthropod evidence, which involves taxa with a typical geographic distribution.
Not maximal

In the research of Lutz et al . [2021], Google search results for " forensic entomology " reached 2,190,000 hits [requests from browser users ], in the form of mass media articles, research, to videos and interviews.

“But despite positive developments and improvements in this field, particularly in the last 20 years, we note that insects are still rarely considered as a tool in forensic cases.”

Insects are one of the most powerful tools in determining PMI minutes and narrowing down the time since death, with minimal sampling effort. This conclusion comes from an analysis of nearly 1,000 cases.

"Therefore, we can hope that forensic entomology has experienced a heroic victory in forensic science, but this is not the case," he said.
There are three relevant problems that they identified, which hinder and impede the breakthrough and acceptance of forensic entomology. First , all investigators, forensic biologists, crime scene technicians, and forensic pathologists, must know forensic entomology and be aware of the potential power of insects in investigations.

“Not knowing about the use of insects in homicide investigations is unacceptable or even malpractice. "Therefore, related institutions [police academies, universities, etc.] must implement forensic entomology in their curriculum," he said.

Second , constraints regarding who is responsible for preserving insect evidence, as well as the idea that “all this sampling will be done later at autopsy by a forensic pathologist” [because all the insects are apparently present on the corpse] can lead to incorrect or incomplete sampling .

“In this case, the prompt involvement of an entomologist, even if only in an advisory role via telephone or social media, can improve the security of evidence, especially at the scene of death.”

Third , evaluation of entomological evidence requires expert knowledge. Forensic entomology is an independent discipline; this means that the forensic entomologist must analyze the evidence, write a report and explain the results ultimately as well as in court during the trial.

“The success of an entomology report depends largely on acceptance of this fact. "However, the quality of the report is greatly influenced by interdisciplinary collaboration between forensic pathologists, investigators and entomologists," he emphasized.

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