Forensic Science Processes: Securing and Packaging Evidence PDF

FORENSIC SCIENCE PROCESSES Securing and Packaging Evidence Forensic investigators most certainly come across many different types of evidence when working a crime scene. This evidence varies in size, structure, and type. Securing this evidence may prove difficult in some cases. Some i...

FORENSIC SCIENCE PROCESSES Securing and Packaging Evidence Forensic investigators most certainly come across many different types of evidence when working a crime scene. This evidence varies in size, structure, and type. Securing this evidence may prove difficult in some cases. Some items can be very tiny, like a fiber or hair, while some items are larger, like a car. There are objects that are solid and stable, such as a gun, and there are some objects that are fragile or are subject to change (like footprints and certain liquids). Nevertheless, it is up to the investigator to package the evidence appropriately, with the main goal being to protect the evidence. Let’s take a look at how some evidence is packaged. Preservation of the evidence requires that an investigator capture and package the evidence in the same condition that it was found. Although this proves to be difficult at times, all attempts are made to maintain the evidence’s integrity. To accomplish this task, the investigator must first choose packaging that is the proper size and material to fit the evidence. This is a key point. Various evidence needs special packaging, so investigators must come to the scene prepared with an assortment of bags, envelopes, tubes and containers. The packaging should be new or clean to avoid contamination. Each piece of evidence should be packaged separately and then properly labeled, sealed and documented. These steps are critical for establishing chain of custody- the unbroken paper trail that follows evidence from the crime scene, through analysis, and all the way to the court room. As we know, when a case goes to court, the defense will look for any sign of tampering or poor record keeping in an attempt to throw out the evidence. Therefore, meticulous procedures must be adhered to so that all collected evidence is bagged separately, secured (using evidence tape), and the chain of custody log completed. Evidence tape must always be signed by the collector of evidence or the person that analyzes the evidence and should never be broken. The purpose of evidence tape is to show if someone tampers with evidence, so it’s important that whoever gains access to the evidence does so in a way that does not break the seal of the evidence tape. For example, if a cigarette butt is collected from a crime scene, investigators will place it in a sealable plastic bag and seal it with signed evidence tape. When a lab technician receives the evidence, they know that they cannot break the seal of the evidence tape and will enter the bag through the bottom (by cutting into it). Once they are finished analyzing the evidence, they will place the evidence in its original package and place it into another bag and seal it, sign it and update the chain of custody log. This process continues through each person that has access to the evidence. There are several different types of packaging that is unique to special pieces of evidence. Small items are usually placed in a bindle, also known as a druggist fold. This ensures that evidence doesn’t fall out during transport. Large items, like pillows and clothing can be placed in paper bags or wrapped in craft paper. TVs, computers and vehicles are too large to be enclosed in a packaged, but they still need to be documented with a tag or label and the chain of custody log completed. © The Trendy Science Teacher 2018 Some evidence is unsafe and investigators must take precautions when bagging this evidence. Gloves are worn, not only to prevent cross contamination, but to also protect the investigator. Needles, syringes, and other sharp objects (like weapons), should be swabbed for DNA and should be placed in a plastic tube or container. When dealing with firearms, investigators must first ensure that the Weapon is unloaded, cleared and safe. The firearm should then be packed in a box specifically designed to hold weapons in place. The outside package label must indicate that the weapon has been cleared. If the weapon has blood or tissue on it, the package is marked with a biohazard label. This label is important because it will alert the lab to safety issues and will also indicate that biologic testing needs to be done before ballistic testing. In additions, any cartridges or ammunition from the firearm should be packaged separately. Certain evidence is degradable. This means that it can break down if precautions aren’t taken to protect the evidence. For example, blood tube samples must be refrigerated immediately. Wet items, such as bloody garments or fresh plants must be air dried or placed in a breathable packaging material to prevent molding. To dry damp or wet items, each item is placed in a brown bag and taken to the crime lab to be allowed to air dry. While drying, white paper is placed under the items to collect any trace evidence that falls. This evidence is processed separately. Arson evidence also requires special packaging. For this type of evidence, packaging that will prevent vapors from escaping are vital. Unused metal paint cans and mason jars are used to package items that may contain accelerants, which evaporate very quickly. Different agencies and state crime labs will have their own specific guidelines for how evidence should be packaged and submitted, so it’s important that investigators are familiar with the rules within their agencies. The bottom line is that the evidence collected at a crime scene is protected as much as possible to preserve the integrity of the evidence. Remember: The Chain of Custody Must NEVER Be Broken. © The Trendy Science Teacher 2018  FORENSIC SCIENCE PROCESSES Securing and Packaging Evidence Close Read Name:________________________________________________________________ Step 1: Skim the passage, highlighting terms that you are unfamiliar with. Step 2: Read the passage, paying careful attention to definitions and examples. Step 3: Define the following terms: Evidence Fragile Preservation of evidence Chain of Custody Evidence Tape Bindle Degradable Step 4: Answer the following questions. 1. Why is the chain of custody important? 2. What is the purpose of evidence tape? 3. How do investigators package really small items, like hair? 4. How do investigators package dangerous sharp items? 5. What must be done with wet items? 6. What should be done with evidence that could degrade? 7. How is arson evidence dealt with and why? © The Trendy Science Teacher 2018 Answer Key  FORENSIC SCIENCE PROCESSES Securing and Packaging Evidence Close Read Answer Key Evidence Items found at a crime scene that can be used to solve the crime Fragile Subject to change Preservation of Evidence is captured in the same condition that it evidence was found Chain of Custody the unbroken paper trail that follows evidence from the crime scene, through analysis, and all the way to the court room Evidence Tape Tape that is used to seal and protect evidence Bindle holds small pieces of evidence- keeps evidence secure Degradable Can break down Step 4: Answer the following questions. 1. Why is the chain of custody important? It maintains the integrity of the evidence and provides a procedure for investigators to follow in order to collect, secure and document evidence. 2. What is the purpose of evidence tape? To show if someone tampers with the evidence 3. How do investigators package really small items, like hair? With a bindle 4. How do investigators package dangerous sharp items? In a plastic container or tube 5. What must be done with wet items? They must be air dried (naturally) and a white paper placed under them to collect evidence that falls. 6. What should be done with evidence that could degrade? It should be placed in a container that prevents it from degrading- ex. Blood (refrigerated), arson items (metal can). 7. How is arson evidence dealt with and why? Arson evidence is placed in a metal can or glass jar to prevent evaporation. © The Trendy Science Teacher 2018