9.1: Introduction

In death investigations, especially those of a suspicious nature, it is critical to accurately determine the time of death for the decedent. This information can establish the timeline of events leading to the death, prove or disprove a suspect alibi or witness statement, and assist the investigator in identifying potential suspects by providing a period of time that will allow the investigator to focus their canvass for eyewitnesses, video surveillance, and digital evidence searches. Historically, it has been very difficult to establish death, let alone the time of the death. Prior to the 1819 invention of the stethoscope by Rene Theophile Hyacinthe Laennec in France, methods of determining death could have been compared with the same techniques to garner a confession under torture, such as placing a candle flame under a finger or burning the nose of the patient. Even if death can be easily determined, figuring out the actual time of death may not be so easy since most deaths, especially suspicious deaths, occur while unattended and without witnesses. According to Darren Drake in his 2020 article, A Time Recorded in History, ‘It used to be that a time of death was simply a time the coroner pronounced, arrived on the scene, or used witness statements to determine when a person passed. Many of those same techniques are used today, but with far greater consequences, if not accurate.’ Most estimations of the time of death are rendered when life-saving measures have ended, whether if the patient was ever responsive to the efforts of the fire or medical personnel or not, or if an officer arrived on scene and determined that death was obvious, rather because of decomposition or an unserviceable physiological derangement. The apparent problem with this estimation of the time of death is that it does not accurately reflect the exact moment of death. Of course, the only accurate determination of the time of death can only be made when the death is witnessed and a person with the authority is present to pronounce death. All other determinations of death are estimations. Where estimations become most problematic is when a body is discovered days, months, or years following the event that resulted in the termination of life. It is in this regard where the study of insects and their arthropod relatives can assist the detectives, medical examiners, and the legal system with determining a window of the death event by establishing: the time interval between the death event and the discovery of the body (also known as the postmortem index or PMI); the post-mortem interval of decomposition; the cause and manner of death; the determination of the death location or the placement of the body after death; and the association of suspects at the crime scene. The science that embodies this study is forensic entomology. Forensic entomologists provide this information by an analysis of insect and larvae morphology, development history, species distribution, and toxicity.

First Use of Forensic Entomology in Court

Aside from the story of Song Chi in Chapter 1, the first documented use of forensic entomology occurred in 1855, when a young couple who were remodeling their small Parisian apartment found the mummified body of a small child hidden in a wall behind the mantelpiece. Even though the couple had only recently moved into the apartment, the police believed they were guilty of the murder of the child. Doctor Louis Bergeret d’Arbois, a physician, conducted an autopsy of the decedent and noticed evidence of insect populations present in the body. By conducting an analysis of the life cycles of the various types of insects, he calculated that the body of the child had been placed behind the mantelpiece in 1848. The Paris police were able to identify the tenants of the apartment in 1848 and arrest them for the murder. They were subsequently convicted following a trial whereby the testimony of Dr. Bergeret was critical to the prosecution.

Forensic Botany

A forensic science that often works in tandem with forensic entomology is forensic botany, which is the study of plants and plant materials. A forensic botanist’s understanding of the growing cycles of plants, as well as the native species of the area, can help to identify the time and place of death. Therefore, it is essential that the crime scene investigator who is tasked with processing the scene of a body found outdoors, or where a body has been buried following a criminal act, must preserve, document, and collect all vegetation surrounding the body, as well as either on the surface or at depths within the grave. Purge fluids from the decomposition process of a human body can destroy all vegetation within 20’ of the body. Therefore, an analysis of that “dying-off” and regrowth cycle can assist with the estimation of the time of death or deposit of the body.