Cjs215 v4 wk4 crime scene biological evidence PDF

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Crime Scene: Biological Evidence...

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CJS/215 v4

Introduction to Forensics Crime Scene: Biological Evidence Part 1: Find, Identify, and Preserve One of the aspects of forensic science that can help solve crimes for years is biological evidence. Consider a crime scene that your team might have been called to this week. The supervisor of your crime scene unit wants to see what you have learned. For Part 1, identify at least 5 different types of biological evidence and explain how to collect and preserve it. Biological Evidence

Collection Method

Preservation Method

Saliva

Using a single wet cotton swab or piece of wet filter paper laid passively on the skin has been effectively used to collect saliva from the skin.

Typically, saliva and other body fluids are refrigerated (or frozen) to prevent or slow the degradation process.

Blood

blood evidence is generally collected from blood pools but can be collected off of clothing as well, using a gauze pad or a sterile cotton cloth.

Ethyl alcohol-saline-sugar solutions preserve erythrocytes for at least 150 days; they are excellent preservatives for the agglutinogens. Whole blood preserved with glycerin-raffinose-glucose may be frozen at —20° C. for at least two months, and probably for a longer period, without excessive hemolysis after thawing.

Bone

This type of evidence item can be picked up with a clean pair of forceps.

Item should be placed in a clean container without any added fixatives. Each container should be properly sealed and labeled, and stored in a freezer.

Hair

Comb the individual's hair over clean white paper using a clean fine-tooth comb. Carefully fold the paper together with the comb into a bindle to prevent loss of any trace evidence. Place the bindle in an envelope and label with appropriate information.

Hair found at the scene should be placed in a paper packet and then placed in an envelope. If a microscopic examination is required, then 15-20 representative hairs from the suspect must be submitted to the lab for comparison. If DNA analysis if going to be used, then a whole blood sample from the suspect must be submitted to the lab in a

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Title CJS/21 v5 Page 2 of 3 Biological Evidence

Collection Method

Preservation Method "Vacutainer."

Urine

Sterile container Collect 100 ml of urine.

Fecal Material

Vaginal Secretions

There is no specific steps to preserve fecal materials because the components that are in the fecal are basically indestructible. Use separate swabs and slides to collect 1 and plate material collected from the external genitalia, vaginal vault and cervix; lubricate speculum with water not lubricant or collect a blind vaginal swab

Each evidence must be dried before packaging. If a damp swab or other biological evidence is placed in a plastic or glass container, it will create a favorable environment to the development of bacteria and fungus, thus accelerating the degradation of DNA. If drying is not possible, evidence should be frozen.

Cotton swabs and Use swab and slides to collect and 1 microscope slides plate material; lubricate instruments with water, not lubricant.

Seminal stains on panties, clothing, bedsheets, pillows and other movable objects should be collected as is. If an article has a wet stain on it, the stain must be allowed to air dry thoroughly prior to collection of the article. If the stain is on a large object that can be cut, then the stained area should be cut using a scalpel or scissors. If the stain is on immovable, nonabsorbent surfaces, then the stain should be scrapped using a clean scalpel onto clean paper, and fold the paper into a druggist fold container. Each item should be packaged separately in a clean paper container. Each item’s packaging must be properly sealed and labeled. Packaged items should be refrigerated if possible, and submitted to the laboratory as soon as possible.

Saliva Semen

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Title CJS/21 v5 Page 3 of 3

Part 2: Significance of Evidence In Part 1 you identified various types of biological evidence your unit located at a crime scene. Your supervisor wants you to write a report in which you explain the significance of the various types of evidence as it relates to the investigation of the crime. Write a 350-word summary of the evidence collected and its use in forensic toxicology.

Please do not touch, change or alter anything until it has been identified, measured and photographed is the Golden Rule of any crime scene. It is also very critical to preserve Forensic Evidence in all criminal investigations, or in any investigation that may result in criminal charges. Testing for drugs is an

important step for most scientific and forensic toxicological circumstances, both for evaluating the realism of the exposure and/or intoxication as well as for evaluation of the level of drug flowing in the body over a certain period of time. Saliva is a complex biological fluid secreted by acinar cells of the major and minor salivary glands. It is an indicator of various plasma constituents. ... It is an important discriminating element in forensic biology, act as an indicator of salivary gland conditions, toxicological and drug monitoring. Blood sample is of particularly useful to the forensic toxicologists since the drug or poison existence in blood shows that exposure followed by absorption has taken place, hence a recent exposure might be ascertained. Hair is a unique and challenging matrix for forensic toxicological testing in that detailed information on historical use is recorded over time as compared to traditional blood and urine matrices. ... Specimens can be more easily obtained with less embarrassment, and hair can provide a more accurate history of drug use. Islam Amine Larabi, Mohammed Riffi, Nicolas Fabresse, Isabelle Etting and Jean-Claude Alvarez, Validation of an UPLC-MS/MS method for the determination of sixteen synthetic cannabinoids in human hair. Application to document chronic use of JWH-122 following a non-fatal overdose, Toxicologie Analytique et Clinique, 10.1016/j.toxac.2019.10.005, (2019).

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