THE PROCESS OF
DECAY AND
DETERMINING THE
TIME OF DEATH
6C 3
 Forensic scientists utilize various methods to estimate the time of death, particularly
when a body is discovered more than 48 hours after death.
 In such cases, body temperature and muscle contraction are less useful, and the
focus shifts to other indicators, such as:
 the extent of decomposition,
 stage of succession,
 forensic entomology,
 and environmental conditions.
STAGES OF DECOMPOSITION
DECOMPOSITION PROCESS
 Initial Breakdown:
 Catabolic Enzymes: After death, digestive enzymes in the gut start breaking down the
walls of the intestines and surrounding tissues.
 Lysosomes: Cells begin to die due to a lack of oxygen. Lysosomes rupture and release
lysozymes, which further break down cell components.
 These processes create a suitable environment for microorganisms responsible for
further decay.
STAGES OF SUCCESSION
 Colonization:
 Anaerobic Bacteria: These bacteria thrive in the oxygen-deprived, lactic acid-
rich environment of muscle tissues after death. They multiply rapidly and begin the
process of decomposition.
 Blowflies: Blowflies are among the first insects to arrive at a dead body, often
within minutes. They are attracted to the moisture and smell from natural body
openings (e.g., eyes, mouth) and any wounds. They lay eggs, which hatch into
maggots that feed on the body tissues.
 The time taken for the blowfly life cycle to
be completed is highly dependent on
temperature.
 The times shown in the diagram refer to
a temperature of 12°C. In colder weather,
maggots grow more slowly, extending the
duration of each stage of their
development.
 Conversely, in very hot conditions, they
complete their life cycle much faster.
 This temperature dependency is crucial
for forensic entomologists, as it allows
them to adjust their estimates of the time
of death based on the environmental
conditions at the crime scene.
 Other Insects:
 Beetles: Beetles lay eggs on the carcass; their larvae feed on maggots instead of
the body.
 Parasitic Wasps: These wasps lay their eggs in the larvae of flies and beetles.
 As the body decays, the soft tissues liquefy, and different species of insects, such as
cheese flies and coffin flies, begin to colonize the body.
 Final Stages:
 The body becomes too dry for maggots, leading to colonization by beetles with
strong chewing mouthparts, such as carcass beetles and ham beetles.
 Mites and moth larvae feed on the remaining hair until only dry bones are left.
FACTORS
INFLUENCING
DECOMPOSITION
FORENSIC ENTOMOLOGY
 Importance: Forensic entomology involves studying the insects that colonize a body
after death, providing critical information about the time and conditions of death.
USING DECAY TO DETERMINE TIME
OF DEATH
 Forensic scientists use the extent of decomposition and the types of insects present
to estimate the time of death.
 The presence and development stage of blowflies, maggots, and other insects are
critical in this process.
 Factors such as temperature, exposure, and environmental conditions significantly
influence the rate of decomposition.
 Forensic entomologists provide vital evidence in legal investigations, helping to
determine the time and circumstances of death.