Forensic Entomology: Role of Insects in Estimating Time of Death

Forensic entomology is the branch of forensic science that deals with the study of arthropods, particularly insects, which are linked to crime and other areas of the legal system. It plays a crucial role in estimating the time of death, also known as the postmortem interval (PMI). This field combines entomology and forensic science to provide valuable evidence in criminal cases. Through the examination of insect life cycles and their colonisation patterns on decomposing remains, forensic entomologists can assist law enforcement in determining when a person died.

The roots of forensic entomology trace back to the 13th century in China, where insects were used to solve murder cases. The first recorded use of forensic entomology can be found in a book authored by Sung Tzu, titled ‘The Washing Away of Wrongs’. In the said book, there is a case illustrated, wherein, to find the murderer of a farmer, all the suspects were asked to lay their sickles on the ground, and only one sickle attracted blowflies and this led to the confession of the murderer. In Europe, significant advancements occurred during the 19th century. In India, forensic entomology gained recognition much later. The first systematic application occurred in the late 20th century, with experts like Dr. K.K. Sharma advocating for its use in criminal investigations. With increasing awareness and training among law enforcement officials, forensic entomology began to be integrated into Indian legal systems.

One landmark case demonstrating the efficacy of forensic entomology in India is the notable case in Jabalpur, Madhya Pradesh (2012), where a murder victim was found with insect evidence that indicated the time of death was consistent with the suspect's timeline. Dr. Meenakshi Bharti, a scientist from the Department of Zoology at Punjabi University, Patiala, collaborated with the police to estimate the PMI using maggots found on the victim's body. By analysing the developmental stages of these insects, Dr. Bharti provided crucial information regarding the time since death, which was instrumental in the investigation.

The Indian judiciary has increasingly recognised the importance of scientific evidence, including forensic entomology. In several rulings, the Supreme Court has emphasised that such evidence can significantly contribute to establishing facts in cases involving suspicious deaths. The court has noted that while traditional forms of evidence are essential, modern forensic techniques enhance the reliability and accuracy of investigations. In the 2016 case of M. Sakthivel vs. The State before the Madras High Court, the court noted the potential of forensic entomology in determining the time of death. The judgement referenced a study highlighting methods to estimate the post-mortem interval based on insect activity.

Recent advancements in forensic entomology focus on improving accuracy in estimating PMI through various scientific techniques. Research has explored methods such as Accumulated Degree Hours (ADH), which considers temperature variations affecting insect development rates. This approach allows for more precise estimations based on local environmental conditions. Moreover, scientists are investigating genetic markers within insect populations to differentiate between species and understand their life cycles better. Techniques like hyperspectral imaging are being developed to analyse decomposition stages non-invasively, providing additional data for forensic investigations. Recent studies have also highlighted the role of microbial communities associated with decomposing bodies and their interaction with insects. Understanding these relationships can further refine PMI estimates and enhance the overall reliability of forensic conclusions.

Forensic entomology is an invaluable tool in modern criminal investigations, particularly in estimating the time of death. Its historical roots and evolving methodologies underscore its significance within legal frameworks globally and in India specifically. As research continues to advance in this field, its integration into forensic science promises to enhance investigative accuracy and justice delivery.

(Dr. Kumar is a retired IPS officer and forensic advisor of Government of Assam. Bora is a student of MSc Forensic Science at National Forensic Sciences University, Guwahati.)