Imagine that you are a crime scene investigator, and you have been asked to present at a forensic science conference due to your department’s recent success in garnering a murder conviction in a decad

Imagine that you are a crime scene investigator, and you have been asked to present at a forensic science conference due to your department’s recent success in garnering a murder conviction in a decad
Unit V: Serology 1 Evidence comes in many shapes, forms, and sizes. Within a crime scene investigation, particles such as metals, paint, and soils are tested for DNA or other physical evidence relating to the offense. Since 1985, after DNA was discovered, forensic science and the study of genetics has continued to evolve in not only the methodologies to analyze but also in the detection of genetic markers as well. Trace evidence identifies materials that could be transferred during the commission of a crime. Materials may include hair, fibers, and fabric, soils, and glass. Physical contact between a suspect and a victim can result in a transfer of trace materials. At a crime scene, there are often tiny fragments of physical evidence that can provide information as to what happened. Once the evidence is collected, scientists examine the physical and chemical properties of trace evidence. In this section, we’ll discuss the importance of how these items are tested and what information is used to solve these cases. Trace evidence at a crime scene can provide valuable information. For instance, if a person has contact with a metal object, metal ions may transfer from the object to their skin or clothing. These ions are detected under fluorescent lighting. Typically, the color of the fluorescence can indicate the type of metal contacted. This technique is often used in the examination of an apparent self -inflicted gunshot wound. Also, when examining 2 the scene of a crime, scientists use metal detectors to search for evidence. Metal detectors help to locate small metal objects, such as bullets or cartridge casings. These objects contain a lot of evidence that may help to explain what happened at the crime scene. 2 Metals, paint, and soil: Paint is considered a trace evidence in many circumstances. For example, small flakes on an individual’s clothing who has entered into a property or damaged an item that has paint on it may have transferred material on to him or herself. In order to evaluate the circumstances in which the paint was impacted, scientists use microscopic examination of a control paint. This control paint is then compared to the samples from the crime scene or to the sample that came from the suspect’s clothing. 3 Soil or mud is often discovered from the suspect’s clothes and/or clothing. In a vehicle accident, the soil may be from the tires that are potentially linked to the scene. In forensic science, one of the most highly regarded and significant trace evidence materials is soil. The significance is that soil is also difficult to interpret. Forensic soil analysis just as paint and glass analysis is comparative. Evidence is found on the victim or the subject and then is compared to that of the crime scene. Soil evidence is typically tested by a professional geologist. 4 Forensic serology: Forensic serology is the identification and classification of bodily fluids such as blood, saliva, urine, and perspiration. These fluids are tested to determine if there is a relationship to a specific crime scene. More importantly, physical evidence is routinely processed by crime labs in search of the presence of bodily fluids such as blood, seminal fluid, and saliva in order to obtain DNA. In the forensic community, serology and DNA analyses are closely related. Serology analysis refers to the screening of evidence from the body, such as fluids while DNA analysis refers to the individualized body fluid that identifies a specific person. In most cases, body fluid classification is performed first before DNA identification is attempted. 5 Evidence at the scene of a crime can provide a lot of important information that may help solve the criminal case. It is important to document, collect, and preserve all evidence found at the scene of a crime. Improperly handled evidence can weaken and potentially destroy a criminal case. If the evidence is documented, collected, and stored correctly, then it could potentially help a case even years from now. A crime lab uses many techniques when analyzing evidence, such as the following: Conventional serological analysis — which this is analyses of the proteins, enzymes, and antigens present and blood evidence — this type of testing does not statistically identify suspects. Restriction fragmented length polymorphism, or RFLP DNA analysis, which is direct analyses of certain DNA in the white blood cells. The DNA is less susceptible to degradation than proteins, enzymes, and antigens. Polymerase chain reaction DNA analysis, which is analysis of DNA that has copied multiple times. PCR analysis will be as statistically individualizing as RFLP in the near future. Forensic serology begins at the scene of the crime. The scene of the crime is first examined by trained professionals who walk through the immediate area. The trail of evidence is usually marked by the point of entry, location of a body, areas where the suspect may have been, and point of exit. The purpose of the walkthrough 6 is to note the location of the evidence and to outline how the scene will be processed. Then the evidence is examined at the laboratory. Prior to the examination, the forensic scientist must evaluate the type of crime based on the samples submitted so that the evidence can be processed properly. After these samples are tested using forensic serology, the tests are set to DNA examination. For much of the 20th century, serology techniques have been used, many of which have been unchanged although the applications in technology for DNA analysis have been undergoing constant change. Both studies contribute to the medical science of classifying and identifying evidence and elements of the body in connection with criminal evidence. 6 DNA as a forensic tool: DNA evidence is extremely important in connecting the individual to the facts of the case. When properly handled, DNA information is hard to challenge. The DNA is used to identify the perpetrator and victim. As technology advances, forensic scientists are able to analyze smaller samples of DNA to develop a profile. In most cases, meaning frequently, DNA analysis is used to acquire information from biological material, which then aids in the subsequent inquiries associated with criminal as well as disaster events including missing persons. In some jurisdictions, a DNA sample is take from the accused during the process and fingerprinting of the arrest. 7 DNA evidence is collected and verified through testing. A majority of collection of trace evidence sampling is done utilizing swabs. Utilizing the swabbing technique on an area requires one to use a moistened swab to transfer the material being collected from an area multiple times. Most DNA samples submitted to a laboratory undergo the following process. Extraction — that’s releasing the DNA from the cell. Quantitation, determining how much DNA you have. Amplification — producing multiple copies of the DNA in order to characterize it. Separation is separating amplified DNA product to permit subsequent identification. The analysis and interpretation, now quantitatively and qualitatively — this is comparing DNA evidence samples to known DNA profiles. Last is quality assurance, reviewing analysts’ reports for technical accuracy. It is important that biological evidence is properly collected and stored, as it can be easily degraded when exposed to natural conditions. Evidence is typically stored in cooler environments. Forensic DNA testing has the ability to solve many crimes in both current and cold cases. 8 Summary: The examination of evidence typically begins with microscopic testing of a control paint, soil, metal, or other substance. In forensics, serology and DNA analyses are closely related. Trace evidence found at the scene of a crime can be transferred to and from the suspect and the victim. The evidence collected and tested can help solve criminal cases, current and cold cases. All forensics neurology and DNA testing are closely related, and in most cases, bodily fluid identification is performed first. The standard method used for DNA analysis by laboratories is forensic genetic material processing in support of criminal case work such as hair, fiber, blood, etc., and identification. The DNA profile is then used to identify or confirm the identity of the suspect and/or the victim. Scientists in law enforcement use this information to support the physical evidence collected at the scene of a crime that will be presented at the criminal trial. 9 10