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Crj310 chap5
This document discusses the importance of evidence in criminal investigations and proper evidence handling procedures. It covers the evolution of forensic science, categories of evidence like physical and testimonial, equipment for processing crime scenes, and maintaining the chain of custody. Specific evidence types are examined in depth, including fingerprints, DNA, firearms, and documents. Proper packaging, transporting, storing, and documenting the chain of custody of evidence is emphasized.
Crj310 chap5
- 1. Chapter 5 Forensics/PhysicalEvidence
- 2. Introduction • Evolutionof law enforcement has benefited greatly from forensic science • Forensic science dates back to 1910 and the “exchange principle” set forth by French criminologist Edmond Locard • Primary purpose of an investigation is to locate, identify and preserve evidence
- 3. CATEGORIES • Testimonial • Documentary • Demonstrative • Physical • Direct • Indirect Definitions
- 4. Investigative Equipment OVERVIEW • Selecting equipment • Equipment containers • Transporting equipment • Training in use
- 5. Crime Scene Integrityand Contamination of Evidence VALUE OF EVIDENCE • Locard’s principle of exchange • Contamination • Integrity of evidence • Chain of evidence • Chain of custody
- 6. Processing Evidence: Maintainingthe Chain of Custody from Discovery to Disposal DISCOVERING OR RECOGNIZING EVIDENCE • Legally seized • Properly processed • Use common sense • Standard of comparison • Forensic light sources
- 7. Processing Evidence: Maintainingthe Chain of Custody from Discovery to Disposal MARKING, IDENTIFYING AND COLLECTING EVIDENCE • Mark, log, photograph and collect all objects • Requires judgment and care • Avoid cross-contamination • Make marks recognizable and small as possible
- 8. Processing Evidence: Maintainingthe Chain of Custody from Discovery to Disposal PACKAGING AND PRESERVING EVIDENCE • Package each item separately • Specific requirements for that type of evidence • Both plastic and paper forms of packaging available • Preserve evidence on immovable items at the scene • Transmittal letter
- 9. Processing Evidence: Maintainingthe Chain of Custody from Discovery to Disposal TRANSPORTING EVIDENCE • Can deliver personally • Use fastest method available PROTECTING, STORING AND MANAGING EVIDENCE • All evidence received is recorded in a register • Some evidence requires more care than others • Automated storage
- 10. Processing Evidence: Maintainingthe Chain of Custody from Discovery to Disposal EXHIBITING EVIDENCE IN COURT • Identify the evidence as that found at the scene • Describe exactly where it was found • Establish its custody • Voluntarily explain any changes that have occurred
- 11. Processing Evidence: Maintainingthe Chain of Custody from Discovery to Disposal FINAL DISPOSITION OF EVIDENCE • Evidence must be legally disposed of • Returned to owner • Auctioned • Destroyed
- 12. Frequently Examined Evidence FINGERPRINTS • Latent fingerprints • Visible fingerprints • Plastic fingerprints • Dusting latent fingerprints • Lifting prints Continued
- 13. Frequently Examined Evidence(Continued) FINGERPRINTS • Chemical development • Other methods • Elimination prints • Inked prints • Digital fingerprinting Continued
- 14. Frequently Examined Evidence(Continued) FINGERPRINTS • Fingerprint patterns, analysis and identification • Usefulness of fingerprints • Admissibility in court • Other types of prints
- 15. Frequently Examined Evidence VOICEPRINTS • Graphic record made by a sound spectrograph • No two voiceprints are alike LANGUAGE ANALYSIS • Psycholinguistics • Excited utterances
- 16. Frequently Examined Evidence HUMAN DNA PROFILING • Identifying, collecting and preserving DNA evidence • Moral and ethical issues BLOOD AND OTHER BODY FLUIDS • Luminol • Bloodstains • Spatter patterns
- 17. Frequently Examined Evidence SCENT • Every person has a unique scent • Scent pads can be presented to a tracking dog HAIRS AND FIBERS • Examining hair • Examining fibers
- 18. Frequently Examined Evidence SHOE AND TIRE PRINTS AND IMPRESSIONS • Can yield valuable investigative data BITE MARKS • Photograph if too shallow to cast • Forensic odontologist
- 19. Frequently Examined Evidence TOOLS AND TOOL MARKS • Common tools are often used in crimes • Tool mark is an impression left by a tool on a surface FIREARMS AND AMMUNITION • Many violent crimes are committed with a firearm • Gunshot residue (GSR) • Shooter ID kits
- 20. Frequently Examined Evidence GLASS • High-velocity versus low-velocity impacts • Glass evidence reference database SOILS AND MINERALS • Forensic geologists • X-ray diffraction • Microscope
- 21. Frequently Examined Evidence SAFE INSULATION • Few people normally come into contact with safe insulation ROPES, STRINGS AND TAPES • Laboratories have various comparison standards • Fingerprints can occur on either side of a tape
- 22. Frequently Examined Evidence DRUGS • Put drugs in a bottle and attach label • Solid drugs in a pillbox WEAPONS OF MASS DESTRUCTION • Designed to produce substantial damage • Acronyms CBRNE
- 23. Frequently Examined Evidence DOCUMENTS • Do not touch documents with bare hands • Identify cellophane/manila envelopes on the outside DIGITAL EVIDENCE • Pervasive nature of cell phones • Digital forensic courses
- 24. LAUNDRY AND DRY-CLEANINGMARKS • Many launderers and dry cleaners use specific marking systems • Submit the entire garment to a laboratory PAINT • Paints are complex and are individual • Use small boxes for submitting paint samples to the crime lab Frequently Examined Evidence
- 25. Frequently Examined Evidence SKELETAL REMAINS • Determine whether remains are animal or human • Forensic anthropology WOOD • If found wet, keep it wet • If found dry, keep it dry
- 26. Frequently Examined Evidence OTHER TYPES OF EVIDENCE • Learn to read product DNA • Manufacturer codes • Discarded items • Lab can provide collecting and packaging instructions
- 27. Evidence Handling andInfectious Disease PRECAUTIONS • Likely to encounter infectious body fluids • Universal precautions • Consider all body secretions as potential health hazards • Constantly be alert for sharp objects • After processing, decontaminate the crime scene
- 28. Summary • Criminalinvestigations rely heavily on various types of evidence • The more individual the evidence, the greater its value • Mark or identify each item of evidence • Package evidence properly • Document custody of the evidence at every stage • After a case is closed, evidence is returned to the owner, auctioned or destroyed
Editor's Notes
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- #7 Learning Objective: Do you know what is involved in processing physical evidence? Processing physical evidence includes discovering or recognizing it; collecting, recording and identifying it; packaging, conveying and storing it; examining it; exhibiting it in court; and disposing of it when the case is closed. Learning Objective: Do you know how to determine what is evidence? To determine what is evidence, first consider the apparent crime. Then look for any objects unrelated or foreign to the scene, unusual in location or number or damaged or broken or whose relation to other objects suggests a pattern that fits the crime. 1- <number>
- #8 Learning Objective: Do you know what the common errors in collecting evidence are? Common errors in collecting evidence are (1) not collecting enough of the sample, (2) not obtaining standards of comparison and (3) not maintaining the integrity of the evidence. Learning Objective: Do you know how to identify evidence? Mark or identify each item of evidence in a way that can be recognized later. Indicate the date and case number as well as your personal identifying mark or initials. Learning Objective: Do you know what to record in your notes? Record in your notes the date and time of collection, where the evidence was found and by whom, the case number, a description of the item and who took custody. 1- <number>
- #9 Learning Objective: Do you know how to package evidence? Package each item separately in a durable container to maintain the integrity of evidence. 1- <number>
- #10 Learning Objective: Do you know how to convey evidence to a department or a laboratory? Personal delivery, registered mail, insured parcel post, air express, Federal Express (FedEx) and United Parcel Service (UPS) are legal ways to transport evidence. Always specify that the person receiving the evidence is to sign for it. Learning Objective: Do you know how and where evidence is stored? Package evidence properly to keep it in substantially the same condition in which it was found and store it securely. Document custody of the evidence at every stage. 1- <number>
- #11 Learning Objective: Do you know how to ensure admissibility of physical evidence in court? To ensure admissibility of evidence in court, be able to (1) identify the evidence as that found at the crime scene, (2) describe exactly where it was found, (3) establish its custody from discovery to the present and (4) voluntarily explain any changes that have occurred in the evidence. 1- <number>
- #12 Learning Objective: Do you know how physical evidence is finally disposed of? Evidence is either returned to the owner, auctioned or destroyed. 1- <number>
- #13 Learning Objective: Do you know what types of evidence are most commonly found in criminal investigations and how to collect, identify and package each? Frequently examined physical evidence includes fingerprints; voiceprints; language; DNA; blood and other body fluids; scent; hairs and fibers; shoe and tire impressions; bite marks; tools and tool marks; firearms and ammunition; glass; soils and minerals; safe insulation; rope, strings and tapes; drugs; bioterror agents; documents; digital evidence; laundry and dry-cleaning marks; paint; skeletal remains; and wood. Learning Objective: Do you know where fingerprints can be found and how they should be preserved? Any hard, smooth, nonporous surface can contain latent fingerprints. Do not powder a print unless it is necessary, and do not powder a visible print until after you photograph it. 1- <number>
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- #15 Learning Objectives: Do you know what can and cannot be determined from fingerprints, DNA, bloodstains and hairs? Fingerprints are positive evidence of a person’s identity. They cannot, however, indicate a person’s age, sex or race. 1- <number>
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- #17 Learning Objective: Do you know what DNA profiling is? DNA profiling uses material from which chromosomes are made to identify individuals positively. Learning Objective: Do you know how identifying blood is useful? Blood can be identified as animal or human and is most useful in eliminating suspects. Age or race cannot be determined from blood samples, but DNA analysis can provide positive identification. 1- <number>
- #18 Learning Objective: Do you know how identifying hair is useful? Microscopic examination determines whether hair is animal or human. Many characteristics can be determined from human hair: the part of the body it came from; whether it was bleached or dyed, freshly cut, pulled out or burned; and whether there is blood or semen on it. Race, sex and age cannot be determined. 1- <number>
- #19 Learning Objective: Do you know where shoe and tire impressions can be found and how they should be preserved? After photographing, cast shoe or tire tread impressions found in dirt, sand or snow. 1- <number>
- #20 Learning Objective: Do you know how to preserve tools that might have been used in the crime, as well as the marks they made? Identify each suspect tool with a string tag. Wrap it separately and pack it in a strong box for transport to the laboratory. Photograph tool marks and then either cast them or send the object on which they appear to a laboratory. A tool mark is compared with a standard-of-comparison impression rather than with the tool itself. Learning Objective: Do you know how to mark and care for weapons used in crimes? Examine weapons for latent fingerprints. Photograph weapons and then identify them with a string tag. Unload firearms. Record the serial number on the string tag and in your notes. Label the packing container “Firearms.” Identify bullets on the base, cartridges on the outside of the case near the bullet end and cartridge cases on the inside near the open end. Put ammunition in cotton or soft paper and ship to a laboratory. Never send live ammunition through the mail; use a common carrier. 1- <number>
- #21 Learning Objective: Do you know how to preserve such things as glass fragments, soil samples, safe insulation material, rope, tapes, liquids and documents? Glass: Label glass fragments using adhesive tape on each piece. Wrap each piece separately in cotton to avoid chipping, and place them in a strong box marked “fragile” to send to the laboratory. Soils: Put one pound of comparison soil into a container identified on the outside. Collect evidence soil the same way. Seal both containers to prevent loss, wrap them and send them to a laboratory. 1- <number>
- #22 Learning Objective: Do you know how to preserve such things as glass fragments, soil samples, safe insulation material, rope, tapes, liquids and documents? Safe insulation: Put samples in paper containers identified on the outside. Rope and tapes: Put labeled rope, twine and string into a container. Put tapes on waxed paper or cellophane and then place them in a container. 1- <number>
- #23 Learning Objective: Do you know how to preserve such things as glass fragments, soil samples, safe insulation material, rope, tapes, liquids and documents? Liquids: Put liquid drugs in a bottle and attach a label. Put powdered and solid drugs in a pillbox or powder box and identify them in the same way. 1- <number>
- #24 Learning Objective: Do you know how to preserve such things as glass fragments, soil samples, safe insulation material, rope, tapes, liquids and documents? Documents: Do not touch documents with your bare hands. Place documents in a cellophane envelope and then in a manila envelope identified on the outside. 1- <number>
- #25 Learning Objective: Do you know what evidence UV light can help discover? Use UV light to detect invisible laundry marks. Submit the entire garment to a laboratory, identified with a string tag or a marking directly on the garment. Learning Objective: Do you know what evidence to collect in hit-and-run cases? In hit-and-run cases, collect paint samples from any area of the vehicle that had contact with the victim. Take paint samples down to the original metal to show the layer composition. 1- <number>
- #26 Learning Objectives: Do you know what can be determined from human skeletal remains? If adequate human skeletal remains are available, the sex, race, approximate age at death, approximate height and approximate time since death can be determined. 1- <number>
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