Forensics: Decomposition & Insects

Many insects are attracted to a dead and decaying body depending upon the stage of decomposition these insects are studied in forensic entomology ranging from flies, cockroaches to necrophagous insects.

The odour of the animal or human corpses immediately after death is very attractive for insects. Some insects’ species are specific in terms of locations, so they are used to determine the geographical location of occurrence of a crime despite a different site of disposal of the body. This study is called forensic entomology.

Forensic entomology is the branch of forensic science in which information about insects is used to conclude while investigating legal cases relating to both humans and wildlife. Such a practice is commonly used to estimate the time of death when the circumstances surrounding the crime are unknown. After decomposition begins, insects such as blowflies are the first to infest the body. The forensic entomologist can identify the specific insect present in the body and approximate how long the body has been left exposed by examining. Environment influences such as climate and weather conditions impact the examination criteria.

Each of the samples should be packed separately and labelled for identification. The packing should be done so that no damage or contamination takes place. The container should be clean. The labels should bear the signature of the forwarding officers along with the forwarding number and date.

Introduction

Forensic entomology is the study of the insects associated with a human corpse. Insect evidence is important as it helps in-

1. Data about insects’ progression can assist specialists with deciding the hour of death (after “PMI”)

2. As well as if the body had been moved from another area before being found.

Most cases that involve a forensic entomologist are 72 hours or more old, as up until this time, other forensic methods are equally or more accurate than the insect evidence. However, after three days, insect evidence is often the most accurate and sometimes the only method of determining elapsed time since death.

According to the studies done by K. Tullies and M. L Goff on exposed carrion in a tropical rainforest, it was found that the decomposition process was best divided into five stages

1. Fresh stage (Days 1-2)

2. Bloated stage (Days 2-7)

3. Decay stage (Days 5-13)

4. Post-decay stage (Days 10-23)

5. Remains stage (Days 18-90+)

Guidelines

Naming – Insects gathered from one piece of the body ought to be kept separate from those from another region. Various species ought to be kept isolated. Every vial ought to be named with: – region, date, time, collector’s name

Handling – Some are delicate and are presumably best gotten with gloved fingers

Packaging – The insects ought to be taken to the entomologist as quickly as time permits. They ought to be kept in a cardboard box as this has heaps of air. Every vial can be taped so that it stays upstanding.

Certaindefinitions of Forensic science are as follows:

“Science as it pertains to the law” (William J. Tilstone, 2006)

“Forensic science is the application of science to criminal and civil laws, mainly – on the criminal side – during criminal investigation, as governed by the legal standards of admissible evidence and criminal procedure” (Forensic Science, 2017)

History

Historically, there have been several accounts of applications for, and experimentation with, forensic entomology. The concept of forensic entomology dates back to at least the 13th century. However, only in the last 30 years has forensic entomology been systematically explored as a feasible source for evidence in criminal investigations. Through their experiments and interest in arthropods and death, Sung Tzu, Francesco Redi, Bergerette d’Arbois, Jean Pierre Mégnin, and the physiologist Hermann Reinhard have helped to lay the foundations for today’s modern forensic entomology.

The first recorded incident where insects were used in a criminal investigation was in 13th-century China as described in Sung Tzu’s book called the washing away of wrongs. When a farmer was found murdered in a field with a sharp weapon, all the suspects were told to place their sickles on the ground. Only one sickle attracted blowflies to the trace amount of blood hidden to the naked eye which resulted in the confession by the murderer.

Uses of Insects in Forensic Science

  • · To escape, the body may have been moved after death. Some of the insects on the body may be native to the first habitat and not the second. This will show that not only was the body moved, but it will also give an indication of the type of area where the murder took place.
  • · The body may have been disturbed after death, by the killer. This may also disturb the insects’ cycle, and the entomologist may be able to determine not only the date of death but also the date of the return of the killer.
  • · The presence and position of wounds, decomposition may obscure wounds. Insects colonize remains in a specific pattern.

 For example, maggot activity on the palm of the hands indicates the probable presence of defence wounds.

  • · Drug’s presence can be determined using insect evidence. There is often not enough flesh left to determine drug presence, but maggots bioaccumulate which can be analysed to determine the type of drug present.

Legal aspect

Forensics is yet to find its place in legal proceedings in our country.

Under Article 138 of the Evidence Act of the Indian constitution, any scientific evidence is allowed before the court of justice to prove a case. Thus, general awareness about this branch of science is required as well as trained professionals.

Collection

Samples of insects of all stages should be collected from different areas of the body, from the clothing and the soil/carpet, etc. Insects will often congregate in wounds and in and around natural orifices.

Flies can be found as- eggs, maggots (in a range of sizes from 1-2 mm to 17 mm), adult flies.

Eggs – Usually found in a wound or natural orifice, but may be found on clothing, etc. Half should be preserved in 75% alcohol or 50% isopropyl alcohol. The rest should be placed in a vial with a little damp tissue paper to prevent dehydration. If no maggots are present, and the only insect evidence is eggs.

Maggots – Found on or near the remains and maybe in maggot masses. The masses generate a lot of heat, which speeds up development.

Following things are to be noted-

1. Site of maggot masses

2. Temperature of each mass

3. Labels which maggots come from a particular mass.

Large maggots are usually older so are most important, but smaller maggots may belong to a different species so both large and smaller maggots should be collected, with the emphasis on larger maggots.

Collect samples of maggots from different areas of the body and the surrounding area and keep them separate.

Adult flies – If adult flies have folded wings, it might have quite recently risen, so it is as yet significant as it very well may be connected to the body. It ought to be gathered, named, and kept isolated. Adult flies can be gathered by net or by utilizing an upset vial. They can be left in the vial without air or food. It can be significant as it shows that at any rate one age of flies of this species has finished advancement on the body.

Beetles – beetles can be found as adults, hatchlings or grubs, pupae, and as-cast skins.  They are regularly found under the body, and in and underdress. They can be set in vials with some air.

Limitations

 (a) Temperature- freezing has a huge impact on the collection and sometimes temperature may put a bar on insects.

(b) Burial – If the body is covered profoundly, insects will be barred. In any case, most criminal burials are not extremely profound as it may disguise the body, and most insects will burrow down.

(c) Wrapped – wrapping must be secure. If the body is wrapped or bundled somehow other insects might be avoided.

Conclusion

Forensics helps in estimating not only PMI but also whereabouts of dead bodies. It may even help in cases of neglect of people who are alive but in need of care by estimating the presence of certain insects. Forensics has not only helped in conviction but has helped in saving many lives. It is an emerging field where the insects feeding on corpses are studied. The insects found on the corpse represent a significant source of information for determining the time of death, which is an evaluation of the post-mortem interval. Additionally, by comparing fauna around the body with fauna found on the body one can obtain information if the corpse was moved after death. Often, insects found on the body point out that infestation by larvae started before death. Entomology is an expanding field and the more cases are being shown and the more researchers are being taught how to use insects as a way of proving responsibility, the more it will develop.

Q&A

 Q.1 What Is the Role of Forensic Evidence in The Investigation of Crime?

Ans. Forensic evidence is used to estimate the time of death when the circumstances surrounding the crime are unknown, entomologist may be able to determine not only the date of death but also the date of the return of the killer.

 Q.2 What Is the Use of Insects in Forensic Science?

Ans. Insects progression can assist specialists with deciding the hour of death (after “PMI”), As well as if the body had been moved from another area before being found. Insects are attracted to a dead and decaying body depending upon the stage of decomposition these insects are studied in forensic entomology ranging from flies, cockroaches to necrophagous insects.

  Q.3 What Are the Limitations of Forensics Entomology?

Ans. Temperature has a huge impact on the collection and sometimes temperature may put a bar on insects. Secondly, if the body is covered profoundly, insects will be barred and, if the body is wrapped or bundled somehow other insects might be avoided.

 Q.4 Explain the History of Forensics Entomology?

Ans. The first recorded incident where insects were used in a criminal investigation was in 13th-century China as described in Sung Tzu’s book called “The washing away of wrongs”. Concept of forensic entomology dates back to at least the 13th century. Through their experiments and interest in arthropods, Sung Tzu, Francesco Redi, Bergeret d’Arbois, Jean Pierre Mégnin, and the physiologist Hermann Reinhard have helped to lay the foundations for today’s modern forensic entomology.

Q.5 What Things Are to Be Noted While Collecting Samples?

Ans. Samples of insects of all stages should be collected from different areas of the body, from the clothing and the soil/carpet, etc. Insects will often congregate in wounds and in and around natural orifices. Flies can be found as- eggs, maggots, and adult flies. Each of the samples should be packed separately and labelled for identification. The packing should be done so that no damage or contamination takes place. The container should be clean. The labels should bear the signature of the forwarding officers along with the forwarding number and date.

References-

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