Name: Date: STEM Worksheet Spring 2018-Indoor Laboratory Stations

Transcription

1 Name: Date: STEM Worksheet Spring 2018-Indoor Laboratory Stations This worksheet exposes you to different types of forensic and criminalistic lines of evidence. You will be analyzing and identifying fingerprints, tools, trauma, blood spatter, and hair in the laboratory and assessing environmental variables that help in the estimation of times since death. Each station has bolded terms that assist you to complete each laboratory exercise. The following exercises will encourage you to think critically about how crime scene investigations and forensic examinations help solve crimes. Group learning is an important part of sharing knowledge and moving learned material from short-term to long-term memory through critical thinking and exchanges with group members. You will be working in a group as you move from station to station. For each station, have one group member read the information aloud to the group. Then, examine the material to answer the questions together. STATION 1: Characteristics Identified Using Microscopy: Reading: Hair is unique to every species and is a type of trace evidence that is collected from the scene, the victim, and the suspect. Examined microscopically, hair reveals characteristics capable of differentiating between human and nonhuman samples. Identifying the class characteristics of hair can either exclude an individual from the scene or is consistent with that individual, which would mean they are a suspect. Should all hair found at a crime scene be collected? Why or why not? Class Characteristics are evidence properties that can be associated with a group, but not with a single source. Class evidence can be parsed into a category but the material is not unique and cannot be attributed to a lone source. Individual Characteristics are the properties of evidence that can be attributed to a specific source, or unique/lone source, with a high degree of scientific and statistical certainty. The key terms associated with hair anatomy include the base, tip, cortex, medulla, pigment granules, and cuticle scale (Figure 1). The medullary index is determined by measuring the medullary diameter relative to the diameter of the hair shaft including the cuticle and can be identified by type (Figure 2). Figure 1: A cross-section of hair with lines pointing to the key anatomic parts of the hair. 1

2 Figure 2: Picture depicting different medulla patterns. With the assistance of an FGCU student, look through the microscope and using the lowest magnification (objective lens) turn the course focus wheel until the hair is in clearly focused. To magnify the hair increase the objective lens and only use the fine focus to make small adjustments. Using the slides mounted on the three microscopes, compare the hair with the images provided in Figure 3. Fill in your answers for slide A, B, and C below. Cat Dog Human Figure 3: Microscopic view of cat, dog, and human hair. Observe the difference in medulla. Slide A: Slide B: Slide C: Was the human hair pigment consistent throughout the length of the hair shaft? How does this compare to the cat and dog? How would you expect bleaching to affect the color of human hair? 2

3 STATION 2: Latent Prints Reading. Latent prints are impressions produced by ridged skin, known as friction ridges, on human fingers and toes. Examiners analyze and compare latent prints to known prints of individuals in an effort to make identifications or exclusions. Although the word latent means hidden or invisible, in modern usage for forensics the term latent prints refers to any finger print that is left on a nonporous hard surface. Alternative light sources (ALS) are laser or LED instruments that project light in different wavelengths or spectrum of light. For example, ultra violet or UV rays can be used to help find latent prints or to detect evidence that may not be readily viewable with the naked eye. With gloved hands, carefully pick up the item provided to you by the FGCU student assistant. Shine the UV light on the item to until the latent prints are exposed. Using fingerprint powder and brush, lightly dust the area where the fingerprint appeared. When the fingerprint is fully exposed use the tape to lift the print and place it on the card provided. What are the benefits of different colored fingerprint powders when using the UV light? Explain. Could you use the powder method on every surface? What type of surfaces would fingerprint powder work best? Critical Thinking: Why do humans have friction fridge patterns (fingerprints) on our hands and feet? Explain. Critical Thinking: Do dogs and cats have fingerprints? What about Gorillas? Explain your answer. 3

4 STATION 3: Fingerprints and Identification Lightly press each fingertip to the inkpad and transfer your fingerprints in Table 1. R. Thumb R. Index R. Middle R. Ring R. Little L. Thumb L. Index L. Middle L. Ring L. Little Section A: Identify fingerprint patterns Use the chart below to identify the whorl, arch, and loop pattern on each of your prints above. Write the pattern in the space provided below each of the finger labels. Whorl Arch Loop Figure 4: This image illustrates the three basic categories of fingerprints. Section B: Identification System Presently, the FBI stores fingerprints in a database known as the Automated Fingerprint Identification System (AFIS). Until recently, the AFIS system was only used in criminal cases, however, now it is used for general identification and fraud prevention. However, before this system was implemented the Hendry Classification System was the preferred method to classify and organize print cards. The Hendry Classification System is a long-standing method used to sort fingerprints characteristics by the presence of a whorl, loop, or arch as well as idiosyncratic traits that used to match an individual or help identify perpetrators of crime. 4

5 Henry Classification System In the space provided, use the equation below, write the number in parentheses ( ) ONLY IF the respective finger has a whorl pattern. Fingers that have an arch or loop pattern will receive a zero. R. Index (16) R. Ring (8) L. Thumb (4) L. Middle (2) L. Little (1) + 1 = R. Thumb (16) R. Middle (8) R. Little (4) L. Index (2) L. Ring (1) + 1 = Fill in the following: + 1 = + 1 = Total the equation by adding the numbers in the numerator, plus one, and then add the numbers in the denominator being sure to add one to the denominator as well. Share your results with your teammates. Twenty-five percent of the population has a 1/1 result. Do you find this to be true in your group? STATION 4: The Estimation of Skeletal Sex from the Pelvic Bones Reading: When evaluating skeletal remains, anthropologists read the bones to estimate if the bones are male or female by evaluating skeletal sex. The anthropologist does not estimate gender from the remains because gender is culturally ascribed. Figure 6 illustrates the nonmetric traits that are used by forensic anthropologists to distinguish between male and female pelvic bones. Read the definitions of anatomical terms below and find them on the bones provided. The ventral arc: located on the ventral surface (smooth area) of the pubis. In a female, it will form a rectangular shape but in a male, the pubis continues to curve down to form the ischiopubic ramus. Sub-pubic concavity: located below the face of the pubis; in females forms a curve (concavity) but in males it lacks a curve. Ridge on medial aspect of pubis: located on the medial aspect of the pubis, directly below the face of the pubis. The ridge is more often found in females than in males, who may present a broader medial surface. The ischial spines tend to be larger and more medially directed in males. With the help of the FGCU student assistant, compare the specimens provided for the following characteristics: (Using Phenice Technique shown below) Figure 5: Image depicting the difference between male and female ventral arcs, subpubic concavity and ridges on the medial aspect of the pubis using the Phenice method. 5

6 Use the example of male and female os coxa (hip bone) provided and the diagrams to estimate the sex of the specimen. Choose A or B, then describe the indicated characteristics that best represent the unknown os coxa in Table 2. Use Yes or No when applicable. Table 2 Os Coxa Characteristics for Males and Females Characteristics Male Female 1 Size of os coxa 2 Size and shape of the sciatic notch 3 Size and shape of the pelvic inlet and outlet 4 Ventral Arc 5 Subpubic Concavity 6 Ischial Spines Is your chosen os coxa (A or B) male or female? Critical Thinking: After learning the skeletal sex characteristics from this lab, what is the evolutionary reasoning for the differences between male and female os coxa? How do you think that c-sections affect the US population for females regarding pelvic dimensions? 6

7 STATION 5: Trauma Analysis Reading: There are different types of trauma that occur on bone including antemortem and perimortem trauma. Antemortem injury can be seen on bone by signs of repair fracture edges will be rounded and breaks will be rejoined. Perimortem (at or around the time of death) injury will show lack of healing and the overall process of bone remodeling. Types of perimorterm trauma include: Blunt force trauma: slow load application to bone over a large surface area such as injuries from a motor vehicle accident, baseball bat, fall from heights, etc. Sharp force trauma: trauma created by a tool with a pointed or beveled edge, such as a knife or saw. High velocity projectile trauma: rapid application of force over a small surface area such as injuries from bullets from firearms. Figure 5: Weapons commonly used in perimorterm trauma Observe each of the crania for trauma. Determine which weapon caused each defect. Cranium A: Cranium B: Cranium C: Critical Thinking: By looking at the gunshot trauma on the example cranium, how would you determine the entrance and exit wounds on the other cranium? Explain your answer. Critical Thinking: By looking at the blunt force trauma on the example cranium, how would you determine which impact occurred first? Explain your answer. 7

8 STATION 6: Human vs. Nonhuman Skull Comparison Reading. Anatomical directions are a standard means to describe relative positions in anatomy. Anatomical Position describes when the specimen is facing forward with the feet and palms of the hands are facing forward and thumbs pointing laterally. The directional terms in Figure 1 are used assuming the specimen is in Anatomical Position. Not pictured are the terms medial (toward the midline of the body) and lateral away from the midline of the body. In anatomical directional terms, the humerus is lateral to the vertebral column and the clavicle is medial to the humerus. Figure 6: The anatomical direction terms used for quadrupedal (dog) and bipedal (human) animals. Working in groups using Figure 7, compare the anatomical directions and characteristics of the skulls provided to answer the questions within the body of Table 3. While observing differences in the skulls listed in Table 3, consider how the morphology reflects the adaptive traits of each species. The shape, size, and locations of cranial traits is indicative of the functions they served for the organism in life. A predatory organism that has a great deal of bite force could be expected to have comparatively larger sites of muscle insertion in areas associated with delivering a strong bite. An herbivorous organism might be expected expect to have cranial adaptations more for chewing. Furthermore, prey animals need excellent peripheral vision to see predators. Consequently, their eyes are more laterally oriented. Prognathic animals, those with large mouths that are pulled in front of their brain cases, tend to be quadrupedal mammals. Non-prognathic animals, such as humans or fossil hominids, have small mouths that that are placed under our brain case. The lack of prognathism in humans has been tied to our use of tools and fire to process food before chewing while prognathic animals tend to bring their faces down to their food. Using the concepts of biological skeletal adaptations related to vision and chewing, evaluate the skulls and place your answers in the table below. Table 3: Please list the cranial traits for the Dog, Cow, Alligator, and Human Skull in the chart below. Remember to compare all of the nonhuman examples to the human. Dog Cow Alligator Bear Human Is the position of the eyes anterior, lateral, superior, or medial? How many sides make up the eyecup? Lateral Five (5) 8

9 Is this animal prognathic? Are there large muscle insertion sites for mastication muscles? Is the cranial vault big relative to the size of the face? Yes No Critical Thinking: Think about predator and prey animals and the relation of their cranial features. What might be the reason why human s eyes are situated the way they are? Dog? Cow? Alligator? Bear? STATION 7: Blood Spatter Reading. Crimes involving violent contact between individuals are frequently accompanied by bleeding and result in bloodstain patterns. Crime scene analysts have found that bloodstain patterns provides valuable insights into events that occurred during a violent crime: Location or position of victim and perpetrator The movement of a bleeding individual Direction of origin and area of convergence Satellite Spatter/spines: indicates the height from which the blood was dropped Elongation: the tail of the blood drop that points to the direction of travel Velocity: an impact spatter pattern travelling by force of feet per second (low, medium, high) Observe the example provided and use the diagrams to answer the questions. 9

10 Figure 5: This image demonstrates how bloodstains take on different shapes when height and angles are changed. Use the materials provided to create drops from different heights. Begin with a single drop of blood from 6 inches in height. Continue dropping a single drop from 1foot, 2 feet, 3 feet, 4 feet and 5 feet. How do the drops change as the height increases? Explain. Place a piece of paper on the clipboard. Using the protractor hold the clipboard at varying degrees. Being with 10 degrees and let one drop hit your paper. Then, increase the angle to 20 degrees, 30 degrees, 40 degrees and 50 degrees. Explain the changes to the drops as the angle increases. Using the exemplars provided indicate which is high velocity, medium velocity and low velocity spatter. High Medium Low Critical Thinking: Using the terms you have learned, describe the differences in blood spatter at a crime scene that involved stabbing verses a gunshot wound. 10

11 STATION 8: Soil Color and the Identification of Strata and Horizons. Reading: The color and composition of the soil at the scene can help law enforcement match the soil adhered to a car tire or clothing to the scene. In addition, soil color changes can also be used to estimate burial depth because the deep soil tends to be placed on top when the grave is filled in by the perpetrators. Because scientific evidence relies upon standard descriptions to ensure that all stakeholders define evidence in the same way, the identification of soil color has been standardized and replicable through the use of Munsell Soil Chart. Examine the tire tread, clothing, and soil samples from the scene and identify the color of the soil using the Munsell soil cards by color, chroma, hue, and value. Table 2: Soil Layers Identified by Globe Color and Depth Color Chroma Hue Value Tire Tread Clothing Scene soil 1 Scene soil 2 Critical Thinking: Were you able to match soil from the scene to either piece of evidence? How would you determine if the soils are found everywhere or unique to a particular area? Explain your answer: STATION 9: Stratigraphy Reading: Stratigraphy is the study of the earth s geophysical layers called horizons, layers, or strata. Changes to soil horizons can be understood through the application of Steno s Laws of Stratigraphy. In particular, geologist Nicolaus Steno recognized that young layers of rock/soil sit on top of old layers of rock/soil (Law of Superposition); that layers of rock/soil are continuous until they encounter solid bodies that block their deposition or until they are acted upon by objects that appeared after the rock/soil was deposited (Law of Lateral Continuity); that rock or soil layers must be older than the intrusion that disturbs them (Law of Cross-Cutting Relationships). Steno s Laws also help law enforcement to use relative dating (the age of an object compared to another) evidence found in burial and surface scatter contexts. Determining these clues helps crime scene technicians to collect pertinent evidence while ignoring objects that are not related to the crime at hand. With Steno s Laws and Relative Dating in mind, check out the terrarium and answer the questions below. Does artifact/physical evidence 1 come from the same time period as artifact/physical evidence 2? Which of Steno s Laws helped you to make that determination? 11

12 Was artifact/physical evidence 3 buried at the same time as the skeletal remains? Use Steno s Laws to explain your answer. Is artifact/physical evidence 4 related to artifact 5? How do you know? Is artifact 6 younger or older than artifact 7? Which of Steno s Laws helped you make that determination? STATION 10: Mapping a scene Proper mapping is crucial in the search and recovery of human remains. We have provided you with a pop-up grid with evidence inside the grid that must be mapped. While law enforcement tends to use inches and feet, we use the metric system (mm and cm). This process also works best if two people measure (one on the smart end of the tape the other at 0) while one is the scribe. The scribe should record the measurement in the table and also plot the points using the graph paper. Do not simply connect the two points with a line. Use the point to sketch the piece of evidence. 12

13 GEMS Spring

14 Table 3: Bone measurement table Specimen Number Anatomical point/ Skeletal element or Misc. Evidence Grid Unit Azimuth (lat.) Meridian (long.) Elevation/ Depth Comments 14

15 STATION 11: Postmortem Change to Skeletal Remains Reading: Evidence changes over time as a result of being in or on the earth. Variables that cause postmortem change include weathering, scavenging, and even the collection process by law enforcement. Weathering is a complex process but sun exposure, wet/dry and freeze/thaw cycles are primarily responsible for physical changes to skeletal material. Weathering of bones and teeth can appear as bleaching from exposure to sun, cracking, flaking, warping, and erosion. When animals scavenge on skeletal material they often leave distinct patterns on bone, such as Punctures: areas of bone that have fallen or collapsed due to the pressure of carnivore tooth pressure. Pits: similar to punctures but fail to pierce all the way through the cortical bone. Scoring: scratches along the cortical surface that usually occur in parallel lines. The lines occur during soft tissue consumption when the animal is making contact with bone. Furrow: similar to a groove or rut on the surface of bone. Evaluate the examples of postmortem change and then identify the types of postmortem change on the evidence in front of you in the box below. Critical Thinking: How does the identification of the type of scavenger help a forensic anthropologist while in the field conducting a recovery? 15