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85 Cards in this Set
- Front
- Back
What is forensic science?
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The application of the principles of natural science to the criminal justice system.
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What is criminalistics?
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The examination of physical evidence
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Mathieu Orfila (1787-1853)
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Established field of forensic toxicology in Spain
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Alphonse Bertillon (1853-1914)
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Anthropometry (study of body measurements)
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Calvin Goddard (1891-1955)
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Developed comparison microscope
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Francis Galton (1822-1911)
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Developed the first system of identification through fingerprints
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Dr. Leon Lattes(1887-1954)
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Lattes crust method for typing dried stains; Discovered blood could be grouped into different categories.
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Albert S. Osborn (1858-1946)
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1st significant text on Questioned Documents
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Hans Gross (1847-1915)
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Principles of criminal investigation
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Edmond Locard (1877-1966)
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Scientific method (cross-transfer theory)
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What is the Locard Exchange Principle?
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Whenever two objects come into contact with one another, there is an exchange of materials between them.
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First lab in U.S. created by August Vollmer in _________________ in 1923
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LA (LAPD)
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FBI lab organized in ________.
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1932
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Forensic Science Research & Training Center established in _______.
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1981
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Federal Labaratories?
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FBI, ATF, USPS, DEA, US Army, Navy & Air Force, Secret Service, US Customs
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Lab Services?
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Physical science – chemistry, physics, geology; Biology- DNA; Firearms; Documents; Photography; Toxicology
Latent Prints; Polygraph; Crime Scene Unit |
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State Laboratories?
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Most populous states have lab or lab system
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What lab accredidation is required in Texas?
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Required by state law
ASCLD-LAB ISO-17025 |
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What is the Daubert Standard?
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Set forth a new standard for admissibility of scientific evidence in U.S. federal courts.
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Kumho Tire Co. V. Carmichael
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applied Daubert to all expert testimony in federal court
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The Frye Standard of 1923
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general acceptance in the relevant field
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Purpose of Frye
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to prevent…the introduction into evidence of specious and unfounded scientific principles or conclusions based upon such principles”
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What is the biggest drawback of Fry?
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excludes relevant, probative evidence; allows arbitrary decision by Judge
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Federal Rules of Evidence 702
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“If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training or education, may testify thereto in the form of an opinion or otherwise.”
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Applying Daubert
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Evaulation by Judge; Judge says your an expert
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Federal Rule of Evidence 703
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the facts or data relied upon in the formulation of an expert opinion be of “a type reasonably relied upon by experts in the particular field in forming opinions or inferences upon the subject.”
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What is an expert witness?
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qualifications; competnency; appearance/demeanor; gives opinion testimony; conclusions rendered :...to a reasonable forensic certainty..."
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Daubert evaluation criteria?
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Empirical testimony (can be tested); publication or peer review; acceptable known or potential rate of error; genearl acceptance in the scientific community.
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Sensitivity?
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minimum amount of a substance required to give positive analytical results
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Specificity ?
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ability to distinguish a substance to the exclusion of all other substances
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Lawyers vs. Scientists
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Speculation vs. confirmation
Innuendo vs. fact-based Absolute vs. no absolutes (terms lawyers use that forensic scientists do not) |
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How does the scientific method apply to a crime scene?
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Each aspect of physical evidence presents an opportunity for applying the scientific method.
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autopsy
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The medical dissection and examination of a body in order to determine cause of death.
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What is Livor Mortis?
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Settling of blood after death; Gravity causes blood to settle at lowest spot;
Apparent 20 minutes – 4 hours after death; Not “fixed” (non-changing) for ~ 3 hrs (blanching upon finger pressure); 6-8 hrs will be fixed |
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Variables that can affect livor mortis?
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Bodies in water, etc. where no fixed position; Situations w/o gravitational effect (spacecraft murder?); Decomposition; Suntan/dark skin;
Anemia; Massive loss of blood |
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What is the visual appearance of livor mortis?
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Usually dark red or purple;
Carbon monoxide poisoning, cyanide results in cherry red or pink appearance; exposure to cold will affect |
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What is Rigor Mortis?
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Chemical changes after death cause muscle tightening; Starts in small muscles and moves to larger; Muscles of face and jaw usually go first; normally occurs within 24 hours and disappears within 36 hours after death.
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What causes rigor mortis?
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Chemical changes involve accumulation and breakdown of adenosine triphosphate (ATP); ATP is the facilitator of muscle movement; When ATP depleted, full rigor results; Loss of rigor due to muscle fiber decomposition;
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Stages of Rigor Mortis
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3 hrs. – no effect
4-6 – neck and jaw 6-8 – more advanced throughout body 12 hrs – full rigor 18-24 hrs – begins resolving, head and jaw are slack 30 hrs – rigor resolved, body limp |
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What variables can affect rigor mortis?
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Muscular individuals experience to higher degree; Antemortem activity can deplete ATP and speed up onset; Death in sleep can slow down due to more ATP at death
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What is a Cadavaric Spasm?
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Onset of rigor is instantaneous but diminishes in normal manner; Brought on by sudden, violent impact such as instantly fatal gunshot wound or collision; Happens but extremely rare
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What is Algor Mortis?
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Time of death determination based on body temperature; Ambient temperature determined as well as body temperature;
Rate of cooling must be known |
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Stomach contents and time of death determination
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Typically digestion begins 15 minutes following ingestion; Lots of variables;
Generally unreliable; Not something a crime lab would be involved with |
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Deduction?
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once a theory has been proposed, the investigator has moved from inductive reasoning to deductive reasoning
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Testing/reevaluating?
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it is important to constantly reassess the theory to avoid the major pitfall of deductive reasoning: tunnel vision
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The goal of reconstruction:
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To develop a likely or probable sequence of events
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What is the purpose of crime scene reconstruction?
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To determine Who?, What?, When?, Where?
How?, Why? |
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What are the duties of the first officer at the scene?
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Make scene safe for entry; Provide medical attention to injured; Secure scene; Preserve physical evidence; Detain witnesses; Request assistance as needed.
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When is the team leader established?
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Prior to arrival.
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Duties of team leader
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Meet with first officer for briefing; Confirm security; Determine legality of search (search warrant); Call for additional personnel/equipment; Survey scene with first officer; Note fragile evidence/establish priorities; Make notes as to initial observations; Work out action plan with team
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What is appropriate crime scene attire?
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Gloves; Shoe covers; Disposable suit; Head gear; Eye protection; Breathing apparatus
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What is appropriate crime scene behavior?
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Do not smoke, eat, drink, etc. within the scene ;Do not bring equipment into scene and set down within the scene if at all possible; Do not place foreign items down in scene
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What is used to document the scene?
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Photography; Video Taping; Sketching; Diagramming; Note Taking (evidence recovery log – chain of custody); Report Writing
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What is the evidence recovery log and why is it important?
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The evidence recovery log is an important document which records all pieces of physical evidence found at a crime scene. This is critical if the case is to be successfully prosecuted later.
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Types of scene searches.
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Scene Searches; Spiral search; Line (strip) search; Grid search; Quadrant (sector)
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Procedure for vehicle search?
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Photograph as found; Begin with exterior exam/print search;
Divide interior into areas; Undercarriage exam (hit & runs); Inventory and document items as removed; Have items tested as appropriate |
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Types of autopsy evidence.
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Hair standards; Blood samples – purple-topped tubes; Prints;
Fingernail scrapings; GSR test; Sexual assault kit; Recovered bullets, etc. |
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When do you NOT use plastic for packaging evidence?
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biological evidence
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How is most evidence packaged?
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Most evidence is best packaged by placing into a clean sheet of paper, folding, taping and placing in an envelope and sealing
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Other rules of collecting evidence.
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Package evidence separately; Use sharps containers when needed; Obtain required control samples; Maintain a chain of custody record; Use biohazard bag to dispose of contaminated items (gloves, shoe covers, etc.)
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Basics for crime scene photography.
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First frame is data card (ea. Roll); General to specific; Outside to inside; Special documentation (street sign, house number, VIN tag, etc.)
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What is scaled photography?
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Camera back is in same plane as subject; Fill frame with subject; Include a scale in 1 photo & 1 w/o scale; Use oblique lighting as required; Use a tripod and remote shutter release.
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What are some specialized crime scene photography techniques?
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Painting with light; Fill-flash; Spray paint “shadowing”;
Luminol |
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Types of physical evidence:
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Blood, Semen and Saliva; Documents; Drugs; Explosives; Fibers; Fingerprints; Firearms evidence; Glass; Hair; Two-dimensional and three-dimensional Impressions; Body fluids and organs; Paint; Petroleum products; Polymers & Plastics; Gunpowder Residues; Serial Numbers; Soil and Minerals; Tool Marks; Vehicle Lamp Bulbs; Wood; Vegetative Matter
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What is the goal of physical evidence?
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To obtain positive identification, association, circumstantial. Individualization.
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Types of crime scene reconstruction.
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On-scene; Off-scene; Re-enactment; Live actors; Mannequins
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What is a class characteristic?
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General and/or measurable features of a specimen which indicate a restricted group source. They result from design factors, and are therefore determined prior to manufacture.
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Define subclass characteristic?
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Features that may be produced during manufacture that are consistent among some items fabricated by the same tool. These are not determined prior to manufacture and are more restrictive than class characteristics.
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Define individual characteristic?
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Marks or features produced by the random imperfections or irregularities of tool surfaces. These characteristics can be used to individually associate a tool to a toolmark.
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How is evidence that may contain DNA stored?
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wrapping paper, mainlla envelopes, and paper bags
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How is clothing that is to be used as evidence stored?
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air-dried; placed individually in separate paper bags to ensure constant circulation of air.
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How is evidence that is charred from fire to be stored?
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Sealed in an airtight container to prevent the evaporation of volatile petroleum residues; new paint cans or tightly sealed jars
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What is chain of custody?
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A list of people who came into possession of an item of evidence.
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What is a standard or reference sample?
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physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence.
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What is a buccal swab?
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A swab of the inner portion of the cheek.
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What is a substrate control?
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Uncontaiminated surface material close to an area where physical evidence has been deposited.
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What is physical evidence?
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Any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator.
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What is a rough sketch?
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A draft representation of all essential information and measurements at a crime scene. This sketch is drawn at the crime scene.
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What is a finished sketch?
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A precise rendering of the crime scene, usually drawn to scale.
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What does indentification of physical evidence mean?
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The process of determining a substance's physical or chemical identity with as near absolute certainty as existing techniques permit.
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What does comparison of physical evidence mean?
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The process of ascertaining whether two or more objects have a common origin.
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What is probability?
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the frequency of occurrence of an event
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IAFIS
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Integrated Automated Fingerprint Identification System (US- FBI)
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AFIS
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Automated Fingerprint Identification System - each state has that is linked to IAFIS
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CODIS
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FBI's combined DNA Index System
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