During a crime scene investigation, evidence are the most important aspects to solve the crime. The evidence left on or around the scene can be used to investigate and identify the perpetrator. “Once the crime scene has been thoroughly documented and the locations of the evidence noted, then the collection process can begin. The collection process will usually start with the collection of the most fragile or most easily lost evidence. Special consideration can also be given to any evidence or objects which need to be moved.
Collection can then continue along the crime scene trail or in some other logical manner. ” (Schiro, n. d. ) Evidence collection is a very sensitive process and if it is done incorrectly, the crime could possibly go unsolved. Contaminated crime scenes can be a major result of unsolved cases. “Contamination is the introduction of something to a scene that was not previously there. Most contamination at a crime scene comes from the humans who investigate it. There are several ways that a crime scene and what is gathered there can become contaminated but a little common sense can alleviate the problem. (Warrington, 2005)
To ensure that the crime scene does not get contaminated, investigators must try to obtain any form of physical evidence as soon as they enter the scene and they must ensure they do not step on anything that could possibly be used as a form of evidence. Blood Stain Blood stain patterns can be used to determine the angle of the shot received, the impact of the shot, the range in which the shooter was standing from the victim, and also the whether the victim had touched the surface of an object after being shot.
Blood analysis is done at the scene to examine the patterns, shapes, and distribution of blood in the location of the crime. Other information can be drawn from this examination such as “distance from the blood source to the target, direction of travel and impact angles, nature of the force used to cause the bloodshed, the object used to cause the bloodshed, sequencing of multiple bloodshed events, and also the interpretation of contact or transfer patterns. ” (Interpreting Blood Stain Pattern, 2015) Patterns of blood stains can be used to determine the impact the weapon caused.
There are two ways in which blood comes into contact with an object, transfer and splatter. The types of patterns caused by transfer are swipe pattern and wipe pattern. “Spatters are created when blood is acted upon by force, and travels through the air before landing on a target surface. ” (Interpreting Blood Stain Pattern, 2015) The direction of blood splatter varies depending on the distance from the perpetrator, the angle in which the shooter stands from the victim, and the weapon used in the crime. “Transfers occur when a blood source comes in direct contact with a target surface area. (Interpreting Blood Stain Pattern, 2015) The motion of the transfer depends on the position the victim fell onto the surface. The texture of the surface can slightly affect the blood splatter.
“Blood stains can occur on a variety of surfaces. The type of surface that free falling blood strikes affects the appearance of the resulting spatter. Blood drops on a smooth surface will make a more uniform or regular circular shape. Blood drops on a rough surface will make an irregular shaped stain with rough or jagged edges. (Interpreting Blood Stain Pattern, 2015) Footwear Impressions “In almost every criminal investigation it is necessary to determine and prove that a particular person or persons may or may not have been present at the scene of a crime. For this reason, the collection, preservation and analysis of physical evidence has become more frequent in the law enforcement community. ” (Footwear, The Missed Evidence, n. d. ) During a crime scene investigation, all foot prints must be investigated as a form of evidence.
Footwear impressions can either be contamination in the crime scene if it belongs to someone who was not present at the time of the crime, or it could be evidence from the either the victim and/or the perpetrator. Footprints that are deemed as contamination to the scene are automatically dismissed and if anything that could have been used as evidence came into contact with the footwear and were tampered with are thrown out. “Footwear evidence can be found at almost all crime scenes in two forms, impressions and prints. The techniques in recording such evidence may be different, but the search is basically the same.
Always use a methodical and planned method of searching. ” (Footwear, The Missed Evidence, n. d. ) There are three categories of prints that can be present at crime scenes, visible, latent, and plastic. “A visible print occurs when the footwear steps into a foreign substance and is contaminated by it, and then comes in contact with a clean surface and is pressed onto that surface. An electrostatic dust lifter can also be utilized when the evidence is in dust. ” These prints can be easily seen on smooth surfaces that can become rigid upon contact.
Plastic prints are impressions that oc when the footwear steps into a soft surface, such as deep mud, snow, wet sand, or dirt creating a three-dimensional impression. This type of impression should be photographed and then cast. These types of impressions are three-dimensional because they allow the examiner to see length, width, and depth. ” These prints are called plastic because they leave indentations. These prints can be easily seen with the naked eyes. “Latent prints are the most overlooked print and are generally found on smooth surfaces.
This type of print needs a variety of powders, chemicals and even forensic light sources to make it visible in order to properly be collected. In most cases these prints should also be photographed prior to any recovery process. ” These prints are the result of sweat, body grease, or oils. (Footwear, The Missed Evidence, n. d. ) Packaging Evidence At a crime scene, objects that are observed as evidence must be packaged and properly labeled for further investigation in order to solve the crime. Packing and labeling are the major aspects of evidence collection.
There are many mistakes that can be made while collecting and packaging evidence. If items are not properly stored for further investigation, evidence can be easily tampered with or become contaminated by unaware individuals. Labeling must be done in order to provide certain information during investigation. “Preserving and maintaining evidence collected at a scene is crucial. The key is understanding evidence and understanding the proper way to package it. Choose packaging of the proper size and material for the evidence. Package each piece of evidence separately, and properly label, seal, and document it.
Evidence tape is designed to fracture easily to indicate tampering; it’s not meant to hold bags shut and boxes together. Use packing tape to seal bags and boxes, then place evidence tape over the packing tape. Sign across the tape, with half the signature on the tape and half on the package. That way, your evidence will be securely packaged, and you’ll notice any tampering. ” For special items such as electronics, there are certain procedures that must be taken in order to preserve information and validity. “Electronic items require special attention.
Cell phones can be activated and deleted from remote sites, which could destroy valuable information. Place cell phones in special bags that block signals and protect from static electricity. These bags can also be used with computer components. If you’re going after computer equipment, bring an expert. Otherwise, you could shut off a computer and discover it was set to automatically delete data. After the expert checks it, then put the hard drive and other sensitive components in protective bags. Any parts that are too large to be packaged need to be documented with a property tag or label. ” (Warrington, Properly Packaging Evidence, 2013)
