Looking at the image in the attached file labeled (Looking at the Image), imagine that you are a crime scene investigator and you have just arrived at the crime scene. Describe the steps you and your

Furthermore, we'll discuss the concept of chain of custody, including the steps that are necessary to maintain the chain of custody and how to secure, protect, and preserve a crime scene. We'll also discuss the general features of bloodstain formations, the information that can be gained from pattern analysis, and what that information tells us about the events involved in the crime.

Lastly, the methods of documenting patterns of bloodstains will be discussed. 2 Critical thinking skills are essential for any analyst in crime scene investigations or crime scene reconstructions. Deductive and inductive reasoning is used by the analysts to find and exploit explicit knowledge of the series of events surrounding a criminal act or an event.

Crime scene reconstruction is a discipline of forensic science. This involves the context evaluation of physical evidence in an effort to identify what happened and the chronological order of events leading up to the act. The holistic approach is the perspective in which an analyst views the development or the circumstances surrounding an event based on the physical evidence discovered, examined, and analyzed.

The elements of evidence are interdependent, and each are significant as a piece to each action and event. 3 Like any investigation, crime scene reconstruction is like putting a puzzle together — although it is much more difficult in that you don't have access to the box top, so you can't have a reference of the shapes, colors, and the textures to help you put that puzzle together.

The analyst does not know how the overall picture of the puzzle is to look in order to help solve it. This takes critical thinking skills. Understanding what is necessary to assess evidence is one of the first steps that an analyst must know in order to render better judgment or reasoning.

Additionally, not all the puzzle pieces may be present and should be identified as gaps in intelligence. But analysis of the pieces that are present must continue to help fill in the holes. Once the analysts have enough pieces strung together in the correct order, the puzzle becomes clear enough to be able to view and even recognize the chain of events that occurred in the commission of the crime. Also, some of the most critical questions about the events may be answered. 4 Areas of importance: Within the discipline of forensic science, investigators will use the following to help them solve the crime or at least determine what happened at the crime scene. Specific incident reconstruction, which deals with homicides, bombings, traffic accidents, event reconstruction, which examines connections between evidence, sequences of events, and the identity of persons, and the physical evidence reconstruction, which focuses on blood, firearms, trace evidence, and other items for DNA analysis.

In order to become a competent reconstructionist, you should possess technical knowledge and a thorough understanding of forensic investigations. While there is no current educational requirements, many analysts and technicians possess undergraduate or even graduate degrees in forensic science. The degrees, though, can range from criminal justice and forensic science, to chemistry, biology, and even in cases engineering. 5 Securing and protecting the crime scene: The first person who arrives on the scene of a crime is responsible for the preservation and the protection of the scene. This is important not only to the investigation but also the reconstruction. Usually, this individual is a patrol officer who may have to deal with a still violent circumstance.

Second, the first person on the scene must attend to any victims who require medical attention. Therefore, he or she will also be part of documenting his or her observations as well as their movements for the crime scene investigators. After the scene has been preserved and protected, the investigators will begin the process of evaluation and recording of the crime scene using video and photography. The systematic search for evidence then begins with the collection of physical evidence for processing and analysis. 6 When setting up a search for evidence, search patterns are established to avoid confusion and contamination of a crime scene in collecting the evidence. Search patterns will include any of the following, and it's dependent upon the crime scene itself as well as the technicians.

These patterns include the strip or line search, a grid search, a wheel or ray search, a quadrant or zone search, a spiral search method. Each one of these methods is dependent, as I said earlier, on the crime scene itself as well as the technicians.

Depending on the number of technicians available and the crime scene, if it's too large, will give a better indication of which kind of search method to use. 7 Collection of physical evidence: During an investigation, all evidence is valued. But each type of evidence provides its own specific value to the investigation. This value should be kept in mind by the investigator. For example, collection of good fingerprints should be given more time and attention than, say, searching for evidence of fibers.

Positive identification of an individual is crucial in investigation. Therefore, having fingerprints that can determine who was at the scene is significant to the overall investigation. In the event that no fingerprints are found, then searching for fibers found on, say, the body of a victim or in the victim’s proximity is the next best thing.

Collection of as much evidence as possible is a best practice because not collecting enough evidence can either hurt or hinder the investigation. 8 Physical evidence continued: Here are a few physical evidence types that may be collected as well as how to handle each of these. Fingerprints, the collection of fingerprints includes not only fingers but also handprints, palm prints, and even bare footprints.

We'll go over shoe tracks later. This type of evidence is the best type to place an individual at the crime scene and should be given top priority. The materials for collecting this type of evidence are very minimal. From the standpoint of cost, this makes fingerprint collection ideal. Collecting fingerprints from any non -movable item at the scene should be processed in place using gray powder, black powder, or even magnetic powder.

Transporting smaller items for processing in the lab is always a best practice. This can be done by placing each item separately in a paper bag or evidence envelopes to go back to the lab for processing. 9 Bite marks: A physical evidence element that is usually found in sexual assaults is a bite mark.

Bite marks may be left by the perpetrator and can be matched just as easily as fingerprints. If bite marks are found, they should be photographed in a normal lighting condition. Alternative lighting should also be utilized such as ultraviolet or UV lights or even side lighting. If an impression was left on the skin, then a casting should be made. For comparison, a cast or a photograph of the suspect’s teeth should also be made. 10 Broken fingernails are found at crime scenes all the time and carry with them very unique characteristics. Much like fingerprints, teeth, bite marks — fingernails carry striations and other markings that make them unique to one individual.

When we talk about questioned documents, these are just documents that are either can be handwritten or typed, and they can be matched to an individual based on such things as how they are handwritten — the ink from a printer or a typewriter and even the paper stock. Left on the paper, oils from the hands can also be traced. 11 Firearms and tool marks: Firearms used in a commission of a crime leave behind a significant amount of evidence. From the bullets that they discharge to the casings found, bullets can be matched to the firearm used. Casings can also be matched to the firearm used through the strike of the firing pin on the casing.

The firearm itself is also part of the evidence as the bullet and casing can be matched directly to the barrel, which leaves striations and marks on both the bullet and the casing. The bullet and casing will tell investigators what make and model the firearm was, the caliber of the firearm as well.

Furthermore, the firearm may have itself other trace evidence such as fingerprints, which should be processed. Remember that all evidence including bullets, casings, magazines, and the firearm itself should be packaged separately. Then, the firearm should be rendered safe prior to any packaging and transportation back to the laboratory. Each item in evidence should be packaged separately.

Tool marks are impressions that are left on surfaces of material. This is referring to the top layer or the outside of an object. Examples such as, say, a basketball, or even the body, the skin surface. 12 Shoeprints and tire tracks: As referenced earlier, shoe prints are just like fingerprints.

Beyond fingerprints and footprints, other evidence of transportation of the subject or the victim can be found in shoe prints and vehicle tire tracks.

Let's tackle shoeprints first. Shoeprints can be compared easily due to the specific tread patters manufactured by companies in the make, style, and the model of the shoe. Furthermore, the way an individual walks provides wear of the shoe tread.

When collecting shoeprint evidence, shoeprints can be lifted just as fingerprints with electrostatic dust print powder.

When not possible, photographs, of course, should be taken at various angles and in various lighting exposures. When taking these photos, a ruler and a level should be used. For tire tracks, cast impressions should be taken when possible. 13 Fracture matches: Fragments of materials, such as wood, glass, plastics, or other materials, should be processed as evidence as they can be used to match items in the suspect's possession.

This can be used to identify a suspect’s connection to a crime or a crime scene. Fibers can be found in various types of material and can be of natural or synthetic substance. Paint, like other materials, has the ability to transfer from one place to another by means of contact.

Whether the paint is chipped or scraped, contact strikes will transfer and, therefore, allow the evidence to be collected from, say, tools, suspects, or other materials for comparison to paint found at the crime scene. Other trace evidence like glass and plastic can be transferred from the perpetrator to either the victim or to a surface. 14 Hair, blood, and bodily fluids are other elements or components of physical evidence.

Hair found at the scene on a victim or even a suspect can tell investigators essential information. If the root sheath is attached to the hair follicle, then DNA can be extracted in order provide information about where the hair came from, specifically providing a certain percentage of the population from which the possible suspect maybe a part of. This is ethnicity, race, color, even age. The hair found may also be compared to the suspect’s own hair sample. If there's no root attached, the analyst may be able to compare the hair samples with the evidenced hair under a microscope for similar characteristics.

When discussing bodily fluids and blood, these are significant elements of evidence.

Bodily fluid refers to and can include seminal fluid, urine, and even saliva. Blood and bodily fluids provide the highest degree of probability to be matched to an individual.

These types of fluids, whether wet or dried, stained, can be collected. 15 Bloodstain patterns and analysis: When an individual is struck and blood is released into the atmosphere, where it lands and how it lands can tell investigators a lot of information. The examination of the location of blood includes the shapes and distributions of patterns, which can help to determine the physical events that occurred.

Some of the analysis may take place right there at the crime scene, while other analyses may take place in a laboratory setting. This can include taking samples and photographs and then writing a detailed and comprehensive report of the analysis.

This is why it is so important to have critical thinking skills as well as the ability to write clearly and concisely to convey the precise interpretations, findings, and ultimately the results.

Written analysis by technicians can explain how the blood patterns were made.

Technicians may also provide their scientific opinions, which are supported by tests, examples from previous cases, as well as legal precedents. 16 When presenting the analysis, the technicians will provide such information as the distance from the blood source, the direction the blood traveled, and the impact angles. This aids in ascertaining the nature of the force used that caused the victim to bleed and, in some cases, even the tool or instrument used to draw the blood. Due to research and development of tools and techniques, they can and have been able to provide the possible object used in blunt force trauma.

Lastly, technicians can help determine the crime's sequence of events as well as the interpretation of contact or transfer of blood stain or spatter patterns. By providing the documentation, which is a detailed and usually comprehensive report and preparing for legal proceedings, this process helps confirm or even refute the position of the victim, the suspect or the defendant, or a witness.

Whether the event occurred as a result of an assault of a single individual, or the struggle that occurred between two or more people can also be determined by this process. In addition, this process can result in the confirmation or the repudiation of statements made by individuals in the case. 17 Let's watch a short video on the main categories of bloodstain patterns. 18 Chain of custody: The process of evidence collection can only begin once the scene has been documented thoroughly and the location of evidence noted. When collecting evidence, most items will be placed in envelopes, bags, and even containers that are usually non -breakable and leak proof. Air -tight, clean metal cans that resemble paint containers are used for evidence collection in arson investigations. Once the packages, envelopes, bags, and containers are sealed they should be then labeled with the collector's initials, the agency's name, case file number, date and time of the collection, and a completed and detailed description to include where it was found.

Whenever the evidence is handed to someone else, regardless of whether the container seal is broken or not, the name of the individual now in custody must sign the chain of custody form to acknowledge that he or she has received it. 19 20