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An overview of the crime scene investigation process. It discusses the roles and duties of law enforcement officers, first responders, and crime scene investigators. It also covers the importance of documentation of evidence, collection of evidence, processing evidence, and ensuring all chain of custody is maintained. the different techniques used to document evidence, including photographs, videography, crime scene sketching, and mapping, reports and note-taking. It also discusses the importance of preserving trace evidence and collecting fingerprints.
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Final Assignment CRJ 622: Introduction to Forensic Science University of Arizona, Global Campus Final Assignment A crime scene investigation is an examination of a crime scene that seeks any clues or evidence that may lead to a suspect or determination of events that took place at the scene. The
investigation will produce evidence that will retell the story that led to the situation at the crime scene. Crime scene investigation is a detailed process, the methodology requires precision and care to reveal important clues, motive, and suspect of the crime. The roles and duties of law enforcement officers, first responders, and crime scene investigators is a very important role to a conducive analysis of a crime scene. Actions taken at the beginning of an investigation will play a vital role in solving a case by determining the facts. The process entails taking careful and concise steps throughout an investigation to preserve and capture evidence without tainting, destroying it, and ensuring witnesses are not overlooked. Other vital components involved in a crime scene analysis; Documentation of evidence, collection of evidence, processing evidence, and ensuring all chain of custody is maintained. The proper steps will ensure that the facts discovered are legally allowed to be entered into a trial. The following paper will take a scenario and analyze each step of the investigation. Approach to the Crime Scene First responders are the first to arrive to a scene. First responders include law enforcement, fire department, and emergency medical services. The responsibility of a first responder is to secure the scene and preserve evidence from becoming destroyed, meaning crime scene evidence should not be touched. In the event that evidence is tampered with or if fire or medical had to disrupt the crime scene, this should be notated for the report and detectives. The initial response is one of the most salient and essential pieces, any tampering with the evidence can result in a false conclusion on the case. First responders are going to be responsible for logging dispatch information, making observations about people or vehicles exiting the crime scene, initial observations of the crime scene, and maintain composure. A first responder will treat the area as a crime scene until otherwise determined. Logging dispatch information is
collect information about Mr. Flora, and have him secured until a detective arrived on scene. Information collected from Mr. Flora would produce information about his arrival on to the property and any information that would indicate evidence being tampered with. This information would later be passed on to detectives that will follow with an official interview. After the scene is secured, witnesses are separated, and the evidence is preserved officers should determine the mode of entry and exit of the crime to establish and alternative path for law enforcement to enter the scene without disrupting the evidence (Weiss, 2020). First responder’s primary role is to secure the scene, preserve evidence, and setup the safeguards for investigators that enter the premise to ensure evidence is not disrupted. In rare occasions, first responders may collect evidence; if a victim has grip of a weapon the weapon may be removed for safety or render care. Severe weather conditions may destroy evidence and bloodstains may be lost if some attempt is not made. Severe thunderstorms may threaten to wash away spent bullets and castings if a shooting occurred in the street (Weiss, 2014). If these extenuating circumstances are relevant to a crime scene, first responders must make every attempt at obtaining photographs and documenting the items and the locations of the items before the collection. This information will be included in the written supplemental report with actions taken at the crime scene, documentation of crime scene log, and witness statements. First responders identified key pieces of evidence in the preliminary search; there were scratches on the lock of the security gate, tire tread mark was located along with a used oil slick, scratches on the garage door to the kitchen, fingerprints with green paint, two handguns, footprints, knife, and the deceased body of the victim. Of the evidence that was discovered, priority to preserve evidence would include any evidence that can be damaged from the elements. The tire slick should be photographed and preserved, the footprints, the knife, the
firearm that was on the ground, and of course the body. Every action that was taken in the crime scene is important to document for the official report, this will ensure that when evidence is entered into court there is a full and accurate report. Documentation of Evidence Documentation of evidence is imperative, as discussed with first responders previously. The documentation does not stop with first responders, documentation happens from several personnel that enter the crime scene. There are several techniques that are used to document evidence; photographs, videography, crime scene sketching, and mapping, reports and note- taking are all essential elements to documenting a crime scene. This process is time consuming and considered one of the most important steps in a crime scene investigation. The primary purpose of crime scene documentation to record and preserve the location and the relationship of discovered evidence, condition of the crime scene as the documenter observes it. The end result will provide an effective notation of all observations within the scene of the crime. This process will help investigators recall the events in the future and allow for proper representation in court. Photographic documentation is done with either film or digital photography. The difference between these two types of methods is the way they record the scenes and converts light into an image. Film consists of a sheet of light-reactive silver halide grains and digital photographs is made when light-sensitive microchip inside the camera is exposed to light coming from the object or scene you wish to capture (Themes, 2016). The nature of digital photographs bring criticism to the ability to manipulate the image with computer software. It is however, that manipulation that allows enhancements to a photograph to brighten and adjust contrast or color balance that makes it effective. Digital photographs must meet specific guidelines to ensure the integrity of the image. Film photographs are done with DSLR cameras or SLR cameras, this
been collected. A sketch allows accurate portrayal of physical facts, establishes the precise location and relationship of objects, helps create a mental picture, assists in interrogations, preparation of reports, and presentation to the court. Sketches are made at serious crimes and accident scenes, after photographs have been taken and before anything is moved (Dutelle, 2016). The sketches will represent a bird’s eye view of the scene, elevation or side view, three dimensional, and other incorporated perspectives (Dutelle, 2016). Crime scene mapping is the crime scene measurements. Baseline mapping, rectangular coordinate mapping, triangulation mapping, polar/grid coordinate mapping, and advanced mapping techniques serves as different tools in capturing the measurements of the crime scene, often dependent on whether the crime scene is interior or exterior. Note-taking throughout each event and documenting throughout the investigation is vital to producing an accurate report. There is not an exception for first responders. With every action that is taking place within an active crime scene, documentation that indicates who, what, when, where are all important to a final report. The information collected is also relevant to the integrity of a court case and the detective and investigators as they dive into the scene deeper. In the scenario that we were provided, trace evidence was present and at risk of becoming damaged or destroyed. The initial first responders should have begun taking photographs of the evidence that was discovered in their initial investigation. The bodily liquids, hair, filaments, fingerprints, footwear impressions, tool marks, firearms, and tire impressions should have been photographed by Officer Able and Bates. The photographic documentation and written documentation are necessary to the investigation and to preserve the evidence, specifically trace evidence as it is easily destroyed or damaged. Two important impressions were at risk of being destroyed after they were discovered by the first responders, tire marks and footprint
impressions. There were two separate footprint impressions, one originating from the ocean that were muddy and one that had blood that was recorded away from the body. These should have been photographed, estimated, and afterwards casted to provide an accurate and undamaged impression. This would be a significant piece of evidence for investigators. Initial documentation pertaining to tire impressions, oil slick, scratched lock, gate, and firearms discovered, fingerprints and scratches on the internal building and external building will all serve as important throughout the investigation. Initial first responders are not going to the entire investigation, but the responsibility does fall on first responders to ensure that the crime scene is safe, render immediate medical attention to surviving victims, capture statements from victims and witnesses, preserve evidence in its original state through documentation, notes, photo/video, and means of preserving the vital pieces of evidence. First responders will be communicating with dispatch through the process of securing the crime scene and determining the entry and exit paths of a suspect to ensure that the areas will not be contaminated by the oncoming officers. Collection of Evidence Evidence collection depends on the evidence that is being collected, there is several methods and techniques that are utilized to effectively secure evidence to ensure that the evidence is not contaminated or destroyed. Proper protective gear is utilized to eliminate the potential risk of cross-contamination. Trace evidence consists of debris: dirt, soil, sand, gravel, grass, leaves, twigs, adhesive tapes, fibers, glass, or bullet fragments (Kleypas & Badiye, 2020). After trace evidence is identified, the collection of evidences includes documentation and photographs of the evidence, proper securing of the evidence by placing in a paper bag or envelope, closing the bag or envelope with a seal or tape with initials of the examiner and the
Fingerprints at a crime scene include latent, patent, and plastic fingerprints. Patent fingerprints are visible on concrete surfaces, latent fingerprints are invisible to the human eye, and plastic fingerprints are found on soft surfaces like wax, wet paint, soap, and caulk. Patent fingerprints are collected with photographs in high resolution and forensic measurement, possibly using alternative light sources or chemicals and dyes during photography. Latent fingerprints must be discovered before they can be collected. This is done through the use of dusting powders on a smooth nonporous surface, black granular, aluminum flake, black magic are powders investigators utilize. When a fingerprint is located, it is lifted from the surface with the use of adhesive tape and placed on a latent lift card to preserve the print (NCJRFS, 2020). Alternative light sources help investigators locate surfaces, doors, doorknobs, windows, railings. The alternative light sources are a laser or LED device that emits wavelengths that can add filters to enhance a fingerprint to be photographed without potentially ruining the print. Investigators also use cyanoacrylate, known as superglue, in processing fingerprints that are on non-porous surfaces. The vapors will adhere to any print on the object and visible with oblique ambient lighting or whit light sources (Forensic Science Simplified, n.d). Chemical developers are also used in collecting fingerprints. The chemicals reach to components of a latent print residue and turn purple, allowing for easier photographs to be taken. Ballistic evidence found at a crime scene involves retrieving bullets, castings, cartridges, and guns from a crime scene. After ballistic evidence is identified, the evidence is diagramed and photographed before it is recovered and secured. Ballistic evidence requires firearm safety, which is the first consideration. Firearms are unloaded with care and precision to ensure that evidence is preserved. Evidence located on a firearm may include fingerprints, blood, hair, fibers, cylinder halos, and debris in the barrel and/or cylinder. The firearm should be handled to
areas least likely to have latent fingerprints, such as knurled or checkered areas. Before the cylinder is moved it should be marked to indicate the position as found, this is done with a pen or scribe marks on the top of the cylinder along each side of the top strap frame. Each cartridge should be repackaged separately and referenced to the information in the report. After proper documentation has taken place, the chamber is cleared and examined visually to ensure that there is no cartridge in the chamber. The firearm, detachable magazines, and extracted cartridges and cases are separately packaged to preserve possible fingerprints. The collection it is collected, documented and photographed. Bullets embedded in wood or plaster are secured by removing a portion of the material it is embedded in. Proper securing of the evidence by placing in a paper bag or envelope, closing the bag or envelope with a seal or tape with initials of the examiner and the date and time. The bag is labeled and a description of the identifying information on the bag or envelope. The firearms and ballistic evidence are transported to the laboratory for further examination. Impression evidence is when several objects are pressed or stamped against one another allowing the objects to transfer and retain characteristics from one another (Byrd, 2000). The most common types of impression evidence found in a crime scene are footprints, tire tracks, bite marks, and tool marks. Specialized lighting is often used when locating impressions, latent impressions or nearly invisible impressions are often difficult to locate (Dutelle, 2016). The four basic methods of recording footwear impressions include photography, documentation/sketching, casting, and lifting (Dutelle, 2016). When an impression is identified, photographs are the first obligation of an investigator. The photographs should be taken at several angles, first without scale so that the impression is not disrupt the impression. After the initial photographs are taken, additional photographs are taken with scale to reference size, the scale must be on the same plane
Footprints that discovered at the crime scene will be photographed without disrupting the scene and then with a measurement scale. The footwear impressions that are present in the mud will need to be casted after the proper protocols are taken. The footwear impression that is present in the blood will not be able to be casted but can be documented through photographs and sketches. These impressions will provide important information relating to the crime. The forms of collection that may be used are adhesive lifter, gelatin lifter, or electrostatic dust-print lifting device. The collection method will be dependent on the environment that the investigators are presented with at the collection time. The plastic prints that are in the mud will be collected by casting, using a powdered stone material like dental stone. Fingerprints at the scene include a plastic print in what appears to be green paint. This will be collected through casting after photographs and documentation is complete. The investigator will begin locating other latent prints through the use of an alternative light source and dusting powders. The fingerprints will be collected with lifting tape and placed on a latent print card. The process of locating prints will be time consuming but necessary. The firearms that are discovered at the scene will be photographed and documented prior to retrieving them. Investigators will take extreme caution to ensure that these are handled with the upmost safety without disturbing evidence that may be present on the firearm. Any castings or relevant ballistics evidence will be secured through proper documentation. The firearms will be unloaded, and each piece will be sealed in in individual bags. Each piece of ballistic evidence and firearms will be photographed, documented, and then contained in an evidence bag with a seal or tape with initials of the examiner and the date and time. The bag is labeled and a description of the identifying information on the bag or envelope. Lastly, the examiner will place a signature, date, and time on the envelope (Kleypas & Badiye, 2020).
The knife discovered at the scene will take similar protocol; photographs and documentation will be obtained. Samples of blood will be collected prior to the removal and securing of the knife. Blood evidence is collected at the crime scene, noting the following information: physical state, amount present, shape, exact location in relation to fixed objects, patter of stains, atmosphere conditions, date and time of observation, and scaled and unscaled photographs of stains (Dutelle, 2016). Gloves should be worn during all collection of evidence and generally a cotton swab is utilized to collect blood samples. With wet blood, a cotton swap is used to soak up the blood, change gloves at each collection, allow the swabs to dry in place or place on a nonporous surface, package the dried swab in paper container and label “Biohazard” on the container (Dutelle, 2016), another collection of unstained area adjacent to the suspected bloodstain should have a sample collected and packaged separately. Dried blood is similar to moist blood, but the cotton swab is moistened with distilled water prior to the collection of blood. Photographs of the scene are taken prior to synthetic compounds are used, scales, or names are included (Kabaliuk et al, 2013). The documentation process involves photographs of bloodstain models using big, medium, and close-up photographs that are paired with scales and identification names. Processing of Evidence Proper collection, documentation, and handling of evidence will allow the processing of evidence effective and accurate. There is not technology that can resurrect evidence that has not been properly handled through its life cycle (Matheson, 2015). Evidence from scene to collecting agency, agency to storage, from storage to the forensic science service proved and back are just a few of the steps in the transportation that evidence will ensue. Evidence can also be transferred
views known and suspect prints side by side and compares minute details and characteristics of a print. These prints are usually persons of interests, victims, and others present at the crime scene. Fingerprints are also running through IAFIS, Integrated Automated Fingerprint Identification System which is the most well-known and utilized fingerprint database in the world and cross reference prints to the database. The evaluation is the part that the examiner decides if the prints are from the same sources, different sources, or inconclusive (Fingerprint Analysis, 2020). An examiner that may find a result inconclusive may reach that verdict if the quality of the sample is poor, lacks comparable data, or has limited or insufficient corresponding and dissimilar features to be certain (Fingerprint Analysis, 2020). When the examiner is complete, another examiner will independently analyze, compare and evaluate the prints and provide a report that supports or refutes the conclusion of the original examiner. There are checks and balances in place to ensure that errors are minimal. Ballistic analysis methods can include many techniques and processes. Some of those are test firing for comparison, bullet comparison, cartridge case examination, serial number restoration, and the National Integrated Ballistic Information Network. Test firing happens after the class and characteristics have been determined and bullets are test fired to obtain a comparative bullet that can then be compared. Bullet comparison utilizes a high-powered microscope, prism mirrors and allows for both sides of a bullet to be compared in hopes of finding matching patterns. The purpose of this is to determine if the bullet was fired from a suspected weapon. Cartridge case examination will use a microscope to identify characteristics of a casing; size, shape, type, size of pin, location of extractor marks, and accidental marks (Dutelle, 2016). This can shed light on the caliber, manufacturer, composition, rim type, and primer (Dutelle, 2016). Serial number restoration resurfaces serial numbers that have been
impressed in a firearm, either by laser or dot matrix punched. Serial numbers leave a lasting impression in the metal and with proper procedure, serial numbers that have been removed can be recovered through magnaflux methods or acid etching methods. National Integrated Ballistic Information Network (NIBIN) is an interconnected system that stores images of bullets and cartridge cases and allows comparison with new samples. The ATF maintains the database that is utilized for comparative ballistics Blood evidence and blood spatter are analyzed through scientific method and examined as evidenced with observation, documentation, analysis, and evaluation to draw a conclusion and peer review. Bloodstain analyst perform a two-phase analysis: pattern analysis and reconstruction. Pattern analysis looks at physical characteristics and stain patterns, shape, appearance, size, and distribution. The factors that are taken into consideration are location and surfaces textures (Bloodstain pattern analysis: How it’s done, n.d.). Reconstruction uses analysis data to put contextual explanations into stain patterns (Bloodstain pattern analysis: How it’s done, n.d.). This identifies what happened, where the blood was originating from, and who the blood came from. This takes into account for any possible disruptions of the crime scene that may have been present, such as emergency response intervention. Reconstruction involves determination of angle of spatter and origin, locating where the victim was positioned in relation to the suspect. Origins are located through the use of 3-D estimations that take into account the height and location of where blood was found. This helps determine the position of the suspect and where he was located during the attack. Tools are used during this reconstruction; elastic strings, protractors, mathematical equations, computer software programs, angles methods, and DNA profiling (Bloodstain pattern analysis: How it’s done, n.d.). Maintenance of Chain of Custody
When deciding what to present in court is an important step in evaluating how evidence will be presented in trial. Evidence includes burden of proof, admissibility, relevance to the case, and sufficiency of admitted evidence. Evidence can include trace evidence, biological evidence, ballistic evidence, impression evidence, and fingerprint evidence. There are four general types of evidence: real evidence, demonstrative evidence, documentary evidence, and testimonial evidence. Real evidence is tangible things, such as a firearm. Demonstrative evidence is a model of what likely happened at the scene at the time of the crime. Documentary evidence includes letters, blogs, or other document that is relevant to the case. Testimonial evidence is a witness testimony, this can include a forensic investigator. Prosecutors will examine evidence found at a crime scene and prove guilt beyond a reasonable doubt. Prosecutors will present clear evidence into the court that demonstrates that a crime occurred, how the crime occurred, and by who the crime involved. Referring back to the scenario provided; prosecutors will demonstrate that there was a probable break-in at the Megabucks home. Evidence of a vehicle will demonstrate the suspect drove on the property of the Megabucks, the tire impression and photographs that were secured from the driveway may be entered if concluded these were impressions outside of known vehicles from the home. Prosecutors would be able to show that the cause of death was by a gunshot wound to the chest. The firearms that were discovered at the crime scene and the ballistic analysis would be presented if relevant to the case. The footprints in the blood and footprints in the mud that have been analyzed would be entered into court, sharing identifying facts about the individual that wore the shoes. Fingerprints and DNA and the analysis would be entered as it is relevant it to case. Conclusion
Investigators and crime scene personnel have a grandiose responsibility, beginning at the initial response. First responders play a significant role in securing the crime scene and preserving evidence. If done correctly, the investigation will be more effective and accurate when concluding the facts of the case. First responders will render aid, secure and witnesses, secure the scene, and preserve and document evidence as it appears on arrival to the scene. First responders will identify the entry and exit point of a suspect to ensure that investigators do not accidentally damage or destroy the evidence. From start to finish, documentation is vital. The documentation evidence will allow for a reconstruction of a crime scene, application of methodical approaches, and enabling accurate conclusions to be drawn. Evidence at a scene is important and all methods involved gathering trace evidence, fingerprint evidence, and biological evidence will be taken so that important aspects and evidence is not missed.Crime scene investigation can be a time consuming and sensitive production, it is important that well trained and educated professionals are involved in the process to promote justice. References Bloodstain pattern analysis: How it’s done. (n.d.). Forensic Science Simplified. https://www.forensicsciencesimplified.org/blood/how.html Parmelee, K. (n.d.). Crime scene Videography revisited. Retrieved from https://www.crime- scene-investigator.net/crime-scene-videography-revisited.html
