Task 3.1 – Research & Analysis Post Mortem Examination (FOIN 3050)
Order Description
Case analysis: late cadaveric changes Specific instructions: • Analyze the video Forensic Field Techniques for Human Remains (see attachment) • Next, you should answer the following questions: a. What is the difference between late cadaveric changes? b. It establishes the different cadaverous changes according to their characteristics. c. Discuss the decomposition process and the effects on the body. d. Mention the insects present in the decomposition process and establish the corresponding stage for each insect. ? Body eliminators ? Predators and body parasites ? Predators and scavenging parasites (predators of waste) ? Insects that the body uses as a refuge • Uses the vocabulary appropriate to the topic and avoids making spelling and syntax errors. • The work must be delivered in MS Word format, Arial font, size 14.
Explanation of the video, please use it to understand the video and do not forget to explain any details of it.
Translation of the video:
Forensic field techniques of human remains
Narrator: Working with human remains is perhaps the most challenging professional and personal area of police work. The stress that involves having to work with the remains of a human being can be considerable. In addition, generally, there is only one opportunity to document and collect the material in a way that maximizes its use for research. This can be a difficult task; but if you follow the proper procedures and recognize when to call specialists to help, it can also be very helpful.
My name is Doctor Scott Fairgrieve. I am a forensic anthropologist. As a forensic anthropologist, I have worked with police officers since 1990, helping them to document and recover bodies from scenes, and also to do some analysis. Together with my colleagues, Professor Tracy Oost and Dr. Gerad Courtin, we will guide you through various aspects of how to handle scenes like these and maximize the potential of the evidence.
Narrator: We will see how to recognize and distinguish human remains. We will examine methods to identify a burial and techniques to conduct a search. We will explain how to set the boundaries of a scene once the remains are found and we will guide you step by step through the procedure to process the scene. We will show you when and how specialists in the field of forensic botany, entomology and anthropology can help. Finally, we’ll see some special situations that happen and that are inevitable, but first we need to understand how we got to this, a human bone in a forensic investigation of someone who was once a living individual.
Narrator: With the initial discovery of any human remains, there are only two things that are known to be absolutely certain, when and where the body was found. By examining the condition of the remains, and with careful consideration of the variables that affect the site, it is possible to extrapolate over time and make an estimate of a key element of that investigation, the time of death.
Decomposition timeline
In this section we will see what we mean by the term postmortem interval or PMI. We will learn to recognize the characteristics that identify the different stages of decomposition, and we will examine some of the many factors that influence the rate of decomposition.
The postmortem interval, or as we refer to PMI, consists of the period of time in which a person dies and the point at which the body was discovered; that period of time can be minutes, they can be hours, they can be days, weeks or even years. The stages of decomposition can really help us determine the PMI for an individual. There are different stages of decomposition that we apply that can help you if you learn to recognize the different characteristics of each stage. Let’s start with the stage in which the body is still fresh, and then comes the stage in which the body begins to swell. There is an active decomposition, an advanced decomposition, and then, in the last two stages, there is the stage in which the body is dry and the stage in which only the remains of the body remain; which many people combine as one because it is very difficult to determine the difference between the two. The stage of freshness goes from the moment of death until the body begins to swell, and this is characterized by a decrease in the body temperature of the deceased and by the appearance of lactic acids in muscle tissues, which cause rigor mortis, as well as the lysosomes with autolytic enzymes, helping in the decomposition of the present cells. Usually, the smell at this point is not very strong, but by the end of this stage an odor begins to be felt. The second stage is the stage in which the body begins to swell; and this begins with an inflammation of the abdominal cavity because the bacteria resident in our body are active and proliferate, because the immune system keeps us under control. This results in an even more profuse odor; and the other thing you will notice is a discoloration of the skin, which can vary from a greenish color to a purple one. This begins to have a pattern very similar to marble. At the end of the swelling stage, you will probably also notice a detachment of the skin, especially in the extremities, so it will look like superficial layers of tissue coming out of the hands, for example, like a glove. The swelling stage will end at the point where the insect activity has perforated the abdominal cavity and the gases start to come out. The third stage of decomposition is the active stage, and during it you have a massive activity of insects. The masses of larvae that have pierced the body cavity are now very prevalent, and the body will have a wet and shiny appearance. It is a very liquid or semi liquid environment. During this stage the odor is very profuse, and also, during the beginning of this stage until the end of it will present a loss of body mass, or biomass, of fifty percent less than what the individual had when he was alive. The fourth stage of decomposition is the advanced stage; and this presents a couple of significant qualities. First, the body begins to dry up and because of that, since much of the biomass has been lost, fifty percent of it disappeared during the active stage, now the larvae feeding on the tissues begin to leave or to migrate out of the body. And by the end of the advanced stage the odor begins to be less prevalent. The fifth stage of decomposition is the dry stage. During this stage, many of the insect activities that have prevailed up to this point are gone and, instead, there are many insects involved
only in the decomposition of the skin and hair and the remaining cartilages, along with the bones and teeth. There may be other tissues, but most of them are dry. By the end of the dryness stage there is not much smell that can be easily detected, unless you are near the remains. The sixth stage of decomposition is the stage of remains, and is rather a continuation of the stage of dryness, so sometimes both are considered one. In the stage of remains, really there is not much skin, but none. It may be that there is some hair left. At this point, the cartilages have usually broken down, and what remains are mainly the bones and teeth, the strongest tissues in the body. At this point you will have to work with the remains to be able to determine any particular smell coming from them.
Now, the six stages of decomposition that I have mentioned are basically the same in any condition. What is different is the period of time involved. For example, if a body is buried, because it was not exposed to ambient temperatures, the decomposition period is longer than it would be for a body that is on the surface. So all the stages remain the same and occur in the same order, but the duration time of each stage is more extensive. The same happens in a marine environment, although the swelling causes the body to float for a period of time, but basically the stages are the same. Simply, the water tempers the differences in temperature and, as a consequence, the stages are elongated. Also, the speed of the stages can be accelerated dramatically in the heat of summer; and in fact, a complete human body can be decomposed from one to two weeks if the temperature and humidity are in the right conditions, that is, a warm temperature and a relatively moderate humidity. There are other factors that affect how quickly a body decomposes, and the stages of decomposition could be things like a fire or a cremation, which obviously accelerate the different stages and things if a body is on a slope or not where the sun It hits you, or if you are in the woods and maybe in the shade. Other factors that can affect the decomposition process include things like a trauma to the body, if there is a wound in the body that the insects feel attracted more quickly, as they are attracted by the natural openings of the body. If a body rests on a particular substrate, such as on land or in concrete, for example, because different substances have different densities and different thermal properties. Rain and excessive humidity, of course, can affect decay as well, mainly because it will affect the insect activity involved in a body during that time. Scavengers are also very important, particularly in natural forest environments. When a body is scavenged and broken into several pieces, decomposition is accelerated. The bodies can also be wrapped in various items, such as rugs, curtains,
bathrooms, and in fact, that attracts even more insect activity because the worms do not like the sunlight to give them directly, so if they have a carpet on which they can hide, or a curtain in which they can get between the sun and the body, they will have a higher level of activity and will break down the body more quickly. The pH of the soil is another factor that we take into consideration. The more acid the soil is, the faster the tissues and even the bones will break down. In fact, burials that occur in very acidic environments eventually dissolve the human bone completely. We have mentioned the humidity, but the aridity or dryness of the area will also affect the decomposition process. The more dry the area, the more likely it is that mummification will occur instead of the body going through the typical stages of fermentation and swelling, so that the body dries up and the liquids that normally attract insects to make the worms appear. They will not be present.
Narrator: The decomposition line, review
The postmortem interval, or PMI, refers to the period of time that elapses between the moment of death and the time when the body is discovered. An estimate of the PMI is what allows the researcher to approximate the time of death. Although the decomposition of the body is a continuous process, there are many characteristics that allow the identification of discrete stages: freshness, swelling, active degeneration, advanced degeneration, dryness and waste. While the order of these stages is constant, their duration does not. In addition to temperature and humidity, there are many other factors that affect how fast or slow each stage will be. Only, considering all these factors, an expert will be able to tie a period of time to each stage and arrive at the most accurate PMI estimate possible.