Crime Scene Basics

1. Crime Scene Basics Forensic Science T. Trimpe 2006 http://sciencespot.net

2. Crime Scene Vocabulary ______________________________: Any physical location in which a crime has occurred or is suspected of having occurred. _________________ CRIME SCENE: The original location of a crime or accident. _________________ CRIME SCENE: An alternate location where additional evidence may be found. _________________: Person thought to be capable of committing a crime. _______________________: Person associated with someone suspected of committing a crime. _____________________: Statement of where a suspect was at the time of a crime. Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm

3. Types of Evidence _____________________evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event. ______________________ evidence refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession. ______________ evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells. What will evidence collected at a scene do for the investigation? • May prove that a crime has been committed • Establish key elements of a crime • Link a suspect with a crime scene or a victim • Establish the identity of a victim or suspect • Corroborate verbal witness testimony • Exonerate the innocent. • Give detectives leads to work with in the case Source: http://www3.sc.maricopa.edu/ajs/crime_scene_technician.htm

4. Crime Scene Personnel ____________________________________are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime. The ______________________________documents the crime scene in detail and collects any physical evidence. The _______________________________is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge. The ___________________________(if a homicide) may or may not be present to determine a preliminary cause of death. ________________________ (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis. ____________________ interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence. Source: http://science.howstuffworks.com/csi.htm

5. Crime Scene Protocol Step 1: __________________ The first step in investigating a crime scene is to interview the first officer at the scene or the victim to determine what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the investigators a place to start. Step 2: ________________ The second step in the investigation of a crime scene, which will help identify possible evidence, identify the point of entry and point of exit, and outline the general layout of the crime scene. Step 3: ________________ The third step in the protocol involves creating a pictorial record of the scene as well as a rough sketch to demonstrate the layout of the crime scene and to identify the exact position of the deceased victim or other evidence within the crime scene. Step 4: _______________ This is the last step in the protocol. The crime scene technician will process the crime scene for evidence, both physical and testimonial evidence. It is the crime scene technicians responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory. Adapted from http://www.feinc.net/cs-proc.htm

6. CORPUS DELICTI“Body of the Crime” • You must prove • that a crime occurred • that the person charged with the crime was responsible for the crime • Top Reasons for Committing a Crime • Source of Evidence • Primary and/or Secondary Crime Scene • Suspect(s)

7. PROCESSING ACRIME SCENE • Isolate and secure the scene • Document the scene • Search for evidence • Collect and package evidence, maintaining the chain of custody • Submit evidence to the crime lab

8. Locard’s Exchange Principle

9. Physical Evidence • Any object or material found • As large as building, as small as hair…odor and submicroscopic like DNA

10. Value of Physical Evidence • Support or reject witness testimony • Link suspect with victim or crime scene • Determine identity of people involved in crime • Allows investigators to re-create crime

11. Evidence – class or individual?

12. Individual Evidence • Anything that can be linked to a unique/individual source • Ex: • DNA pattern • Broken glass that fits together

13. Class Evidence • Object has characteristics common to a group of objects • Ex: • Even despite the different sizes, shades, and brand • there are still thousands of pairs just like them • BUT –

14. Probative Value • Definition: • How can you increase probative value of class evidence??? • What’s the probative value of class evidence vs. individual evidence???

15. Step 1 • The first officer to arrive at the scene is responsible for securing the crime scene. • Priorities should be: • Medical assistance for individuals in need • Arresting the perpetrator • Exclude all unauthorized personnel from the scene.

16. Step 2 • Preliminary Examination • Photography, sketches, and notes are the three methods for crime-scene recording • Ideally all three should be employed; however, as is often the case, personnel and monetary limitations may prohibit the utilization of some

17. Photography • Must be in an unaltered condition • Unless there are injured parties involved, objects must not be moved until they have been photographed from all necessary angles. • As items of physical evidence are discovered, they are photographed to show their position and location relative to the entire scene. • When the size of an item is of significance, a ruler or other measuring scale may be inserted and included as a point of reference.

18. Sketching in relation to Photography • A sketch can: • Depict entire scene in one visual whereas a photograph cannot • Be selective & eliminate distracting confusion • Record spatial relationship between items

19. Types of Sketches • Types of Sketches: • **_________________ • Most common, overhead view, type we will do • Cross projection or exploded view • Cut apart walls like a box & lay flat • _________________ • View from eye level • Perspective • 3D photograph-like

21. Sketches • ___________Sketch —A draft representation of all essential evidence • information and measurements are taken • drawn at the crime scene • Shows all recovered items of physical evidence • Important features of the crime scene (entry, exits, etc) • ______________Sketch —A precise rendering of the crime • drawn to scale • not normally completed at the crime scene • drawn with care and concern for aesthetic appearance

23. Rough sketch should include: • Preparer’s Name • Date and Time • Compass direction • Objects/evidence • Measurements of rooms, windows, doors & furniture • Distances between objects, bodies, persons & entrances/exits • Key/legend

24. Procedure for sketching • Measure all distances • Measure walls, windows, door, furniture, people, guns, shoe prints, etc. • __________________: • There are 3 points of measurement: item of evidence & 2 fixed objects • Triangle is created when measurements are made from each of the 2 fixed points to item of evidence • Rectangular Coordinate Measurements • Measure from 90 degree angle of 2 points

26. Notes • Must be a constant throughout the processing of the crime scene • Should include: • Detailed written description of the scene • location of items of physical evidence recovered • Time and by whom evidence was discovered • How and by whom evidence was packaged

27. Importance of Recording • only a limited amount of time in untouched state • Opportunity to record original state is key • Important for: • Investigation

28. SEARCH METHODS • _________________________in large, outdoor scenes • __________________—basically a double-line search; effective, but time-consuming • ________________—most effective in houses or buildings; teams are assigned small zones for searching • _________________________—best on small, circular crime scenes • ____________________—may move inward or outward; best used where there are no physical barriers

29. Search Methods

30. The Search • Often, many items of evidence are clearly visible but others may be detected only through examination at the crime laboratory. • For this reason, it is important to collect possible carriers of trace evidence, such as:

31. Autopsy • The search for physical evidence must extend beyond the crime scene to the autopsy room • The medical examiner or coroner will examine the victim to establish a cause and manner of death • Tissues and organs will be retained for pathological and toxicological examination • At the same time, arrangements must be made between the examiner and investigator to secure a variety of items that may be obtainable from the body for laboratory examination.

32. Physical evidence collected from body • Fingernail scrapings • Head and pubic hairs • Blood (for DNA typing purposes) • Vaginal, anal, and oral swabs (in sex related crimes) • Hand swabs from shooting victims(for gunshot residue analysis)

33. Packaging Evidence • prevents damage through contact and prevents cross-contamination. • Manilla envelopes, pill bottles, twist on cap glass bottles, paper (using “______________”) • If bloodstained materials are stored in airtight containers, the accumulation of moisture may encourage the growth of mold, which can destroy the evidential value of blood. • In these instances, wrapping paper, manila envelopes, or paper bags are recommended packaging materials.

34. Chain of Custody • _______________—A list of all persons who came into possession of an item of evidence. • Important for court • Adherence to standard procedures in recording the location of evidence, marking it for identification, and properly completing evidence submission forms for laboratory analysis is critical to chain of custody. • **Every person who handled or examined the evidence and where it is at all times must be accounted for.