#Stages of decomposition and estimation of the Post Mortem Interval

[forensicfield]

Forensic Science E-Magazine (Oct-Nov-Dec 2023)

We proudly present the Oct-Nov-Dec issue (Vol 18) of your favorite magazine, Forensic Science E-Magazine. As usual, the magazine's current issue has helpful content related to forensic science. Our editorial team works diligently to deliver the study material while keeping in mind the needs of our valued readers. We are confident that if you read it attentively and patiently, it will go a long way toward giving you the information you need to tackle the difficult process of the exams and study and bring you certain knowledge and victory.

Reputable authors have provided several important pieces on forensic science and science in the current edition. A variety of questions collected from various competitive exams are included in the magazine's most important section.

Contents:

1. Mad Honey: A Comprehensive Overview of Origin, Characteristics, and Medicinal Uses

2. Forensic Entomology and the Role of Diptera in Forensic Science

3. Forensic Podiatry: A Comprehensive Overview

4. Stages of decomposition and estimation of the Post Mortem Interval

5. Glass Fractures

6. Saliva Examination

7. Methods Used for Removal of Serial Numbers in the case of stolen weapons

8. What should a forensic expert do?

9. Forensic Ballistics Experts QnA

10. Definition and Types of Crime

11. ESDA

[todaysbug]

July 12th, 2022

American Carrion Beetle (Necrophila americana)

Warning! Today's bug discusses themes of decomposition, death and forensics.

A carcass is a battleground—at least, it is for the American carrion beetle, among the other flesh-eating flies and beetles which flock to dead bodies. These beetles feed primarily on raw flesh, but also on fungi and insect larvae. They are important detritivores who help reduce the buildup of rotting organic matter. They are found east of the Rockies, throughout the USA and Southeastern Canada.

When something dies, the first organisms to find it will be flies. The American carrion beetles populate the body soon after, within just a few days, when flies have become less active. As soon as they arrive, they begin to feast on the eggs and larvae left behind by flies to give their own brood a chance, then mate and lay eggs on the carcass. Upon hatching, the larvae immediately begin to eat away at the carcass, alongside any pesky competitors they may find on their feasting grounds. The adults stick around to pick at any maggots which may remain, then disperse.

The American carrion beetle is gaining importance in the subject of forensic entomology, an emerging (but not new!) science of decomposition by insects. A post-mortem interval, or PMI, can be determined based on the development of larvae and abundance of adults present on a corpse, allowing investigators to estimate the time of death. These beetles are often found during the dry decay stage, when most of the flesh has been eaten away, leaving dried flesh, skin, bones, hair and sinew for these beetles to eat away at. These insects are also quite useful to find concealed corpses, as they tend to gather around those hidden in places such as suitcases and trash cans.

[aloysiavirgata]

Different than your Rigor Anon, but I’m very curious about forensic entomology and how they estimate the time of death. Any good resources/explanations for the layperson?

I’m not a forensic entomologist but I know a fair bit about it. Here are the basic ideas behind it. I recommend the Sylvia Hunt case for a good case study. William Krinsky’s work on this one is gold standard. Here is a nice little study showing how ADH is used.

1) Different species of insects are attracted to the body at different stages of decomposition.

2) These insects have particularly defined life cycles, the energy needed for which is defined by a concept called ADH.

3) ADH stands for “accumulated degree hour.” Each species has a fixed ADH requirement to go from egg to adult and pass through each larval stage. These have been determined by raising larvae in lab conditions and finding their ADH. There are miles of ADH tables for different species.

4) ADH is defined by the temperature in F x the time of exposure to that temperature.

5) Think of ADH as the energy necessary to cook a piece of meat to well done. You can expose it to high temperatures for a short time (like a grill) or lower temperatures for a long time (like a smoker.) So time and temperature are inversely proportional.

6) If you, say, find a bunch of second instar blue bottle blowflies (one of the first colonizers) on the remains and you know the temperature, you can determine the PMI (post mortem interval.)

7) To do this, you look up the ADH necessary to get from blue bottle blowfly egg to blue bottle blowfly second instar. This is, as I said, a constant. So let’s say, for the sake of convenience, that 1000 ADH (this number is wrong, FYI) are required to go from egg to second instar and you know that the average temperature for the past several days has been about 50F. So you divide 1000 ADH/50F and get 20H. That means the person has been dead less than a day.

8) There are many mitigating factors including whether the body was covered, inside or outside, precipitation, had exposed wounds, had drugs present in the system,  etc. But you get the idea.

[leedsomics]

The "ForensOMICS" approach to forensic post-mortem interval estimation: combining metabolomics, lipidomics and proteomics for the analysis of human bone.

The combined use of multiple omics methods to answer complex system biology questions is growing in biological and medical sciences, as the importance of studying interrelated biological processes in their entirety is increasingly recognized. We applied a combination of metabolomics, lipidomics and proteomics to human bone to investigate the potential of this multi-omics approach to estimate the time elapsed since death (i.e., the post-mortem interval, PMI). This "ForensOMICS" approach has the potential to improve accuracy and precision of PMI estimation of skeletonized human remains, thereby helping forensic investigators to establish the timeline of events surrounding death. Anterior midshaft tibial bone was collected from four female body donors in a fresh stage of decomposition before placement of the bodies to decompose outdoors at the human taphonomy facility managed by the Forensic Anthropological Center at Texas State (FACTS). Bone samples were again collected at selected PMIs (219, 790, 834 and 872 days). Liquid chromatography mass spectrometry (LC-MS) was used to obtain untargeted metabolomic, lipidomic and proteomic profiles from the pre- and post-placement bone samples. Multivariate analysis was used to investigate the three omics blocks by means of Data Integration Analysis for Biomarker discovery using Latent variable approaches for Omics studies (DIABLO), to identify the reduced number of markers that could effectively describe post-mortem changes and classify the individuals based on their PMI. The resulting model showed that pre-placement bone metabolome, lipidome and proteome profiles were clearly distinguishable from post-placement profiles. Metabolites associated with the pre-placement samples, suggested an extinction of the energetic metabolism and a switch towards another source of fuelling (e.g., structural proteins). We were able to identify certain biomolecules from the three groups that show excellent potential for estimation of the PMI, predominantly the biomolecules from the metabolomics block. Our findings suggest that, by targeting a combination of compounds with different post-mortem stability, in future studies we could be able to estimate both short PMIs, by using metabolites and lipids, and longer PMIs, by including more stable proteins. http://dlvr.it/SZN1yW

[marymosley]

Role of Microbial Forensics to Identify time since death

There are various types of microorganisms (virus, bacteria and many fungi) which are found on the earth.  Some of these microorganisms are used in our daily life but number of bacteria, viruses and fungi posses health risk to humans, animals and plants also.  Now a day, crimes are increasing with a higher rate so few people used these microorganisms, pathogens or toxins as bioweapons to attack on the innocents which have serious consequences on human health and economic development. These bioweapons are very dangerous because they can grown from a single cell. Creation of large quantity can be accomplished readily and at low cost. Thus, bioterrorism has become one of the major threat challenges of the 21st century.

MICROBIAL FORENSICS

Forensic science is the application of all sciences in the investigation of criminal and legal cases. The areas of science that are exploited diverse include biology, chemistry, physics and geology. One of the new field of forensics which are used now a days is microbial forensics. Microbial forensics term relates to analysing evidence from bioterrorism act, biocrime or accidental release of dangerous microorganism or toxins for legal purpose. This may also consider as fingerprinting of pathogenic agent, but the unique identification of microorgainism may never be possible because of insufficient data. On the basis of progress of the micro organisms during decomposition we can determination location of crime and the time of death of an individual.

ESTIMATING TIME SINCE DEATH

In forensics and low enforcement, accurate estimation of time of death are critical. Various medico legal contexts are used for determination of time of death of individual. Stage of decomposition is considered as the primary method for the determination of time of death of individual. Decomposition is basically depends on the biotic (bacteria, microbes and insets) and abiotic factors (weather, climate, humidity).  Apart from this, change in algor mortis, rigor mortis, change in vitreous humor and soft tissue components also help in estimation of Post mortem interval. By examining the stages of insert colonies which are found on dead body, we can estimate the time of death of individual. But this method is possible only when the time span was too long that is around few days.

Apart from above, microbes have excellent potential for estimation of post-mortem interval.  First, in different seasons as well as different locations, different types of microbes are produced. Therefore, microbes are used as ubiquitous physical evidence. Second, communities of microbes are often depends on environment. As like other organisms such as plants, environment has a great response on microbes. So which type of microbes are produced in which environment are documented along with which are produced in human gut, glacial till and food products.

 In outdoor death scenes, a predictable change in microbial communities in the abdominal cavity, on the skin of the deceased, as well as in the soils was observed. Microbiome methods are used for capturing these community changes.  Therefore, study of these microbes are used for the estimation of how long a human has been dead. In indoor crime scene, different kind of microbial communities are found.

  Author: Ritu

Ritu has completed M.Sc. Forensic Science from Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS) Prayagraj and Graduation in Botany (H) from Delhi University. She has done training in CFSL, CBI & FSL Delhi in Physics and Chemistry Division. She also has real time scenario experience during her training with Delhi mobile crime team.

The post Role of Microbial Forensics to Identify time since death appeared first on Legal Desire.

Role of Microbial Forensics to Identify time since death published first on https://immigrationlawyerto.tumblr.com/

[marymosley]

Role of Microbial Forensics to Identify time since death

There are various types of microorganisms (virus, bacteria and many fungi) which are found on the earth.  Some of these microorganisms are used in our daily life but number of bacteria, viruses and fungi posses health risk to humans, animals and plants also.  Now a day, crimes are increasing with a higher rate so few people used these microorganisms, pathogens or toxins as bioweapons to attack on the innocents which have serious consequences on human health and economic development. These bioweapons are very dangerous because they can grown from a single cell. Creation of large quantity can be accomplished readily and at low cost. Thus, bioterrorism has become one of the major threat challenges of the 21st century.

MICROBIAL FORENSICS

Forensic science is the application of all sciences in the investigation of criminal and legal cases. The areas of science that are exploited diverse include biology, chemistry, physics and geology. One of the new field of forensics which are used now a days is microbial forensics. Microbial forensics term relates to analysing evidence from bioterrorism act, biocrime or accidental release of dangerous microorganism or toxins for legal purpose. This may also consider as fingerprinting of pathogenic agent, but the unique identification of microorgainism may never be possible because of insufficient data. On the basis of progress of the micro organisms during decomposition we can determination location of crime and the time of death of an individual.

ESTIMATING TIME SINCE DEATH

In forensics and low enforcement, accurate estimation of time of death are critical. Various medico legal contexts are used for determination of time of death of individual. Stage of decomposition is considered as the primary method for the determination of time of death of individual. Decomposition is basically depends on the biotic (bacteria, microbes and insets) and abiotic factors (weather, climate, humidity).  Apart from this, change in algor mortis, rigor mortis, change in vitreous humor and soft tissue components also help in estimation of Post mortem interval. By examining the stages of insert colonies which are found on dead body, we can estimate the time of death of individual. But this method is possible only when the time span was too long that is around few days.

Apart from above, microbes have excellent potential for estimation of post-mortem interval.  First, in different seasons as well as different locations, different types of microbes are produced. Therefore, microbes are used as ubiquitous physical evidence. Second, communities of microbes are often depends on environment. As like other organisms such as plants, environment has a great response on microbes. So which type of microbes are produced in which environment are documented along with which are produced in human gut, glacial till and food products.

 In outdoor death scenes, a predictable change in microbial communities in the abdominal cavity, on the skin of the deceased, as well as in the soils was observed. Microbiome methods are used for capturing these community changes.  Therefore, study of these microbes are used for the estimation of how long a human has been dead. In indoor crime scene, different kind of microbial communities are found.

  Author: Ritu

Ritu has completed M.Sc. Forensic Science from Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS) Prayagraj and Graduation in Botany (H) from Delhi University. She has done training in CFSL, CBI & FSL Delhi in Physics and Chemistry Division. She also has real time scenario experience during her training with Delhi mobile crime team.

The post Role of Microbial Forensics to Identify time since death appeared first on Legal Desire.

Role of Microbial Forensics to Identify time since death published first on https://immigrationlawyerto.tumblr.com/