1. Chapter 5 Forensics/Physical Evidence1-

2. Introduction
Evolution of 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 1-

3. Definitions CATEGORIES Testimonial Documentary Demonstrative Physical
Direct
Indirect 1-

4. Investigative Equipment
OVERVIEW
Selecting equipment
Equipment containers
Transporting equipment
Training in use 1-

5. Crime Scene Integrity and Contamination of Evidence
VALUE OF EVIDENCE
Locard’s principle of exchange
Contamination
Integrity of evidence
Chain of evidence
Chain of custody 1-

6. Processing Evidence: Maintaining the Chain of Custody from Discovery to Disposal
DISCOVERING OR RECOGNIZING EVIDENCE
Legally seized
Properly processed
Use common sense
Standard of comparison
Forensic light sources
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.
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-

7. Processing Evidence: Maintaining the 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
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.
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.
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-

8. Processing Evidence: Maintaining the 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
Learning Objective:
Do you know how to package evidence?
Package each item separately in a durable container to maintain the integrity of evidence. 1-

9. Processing Evidence: Maintaining the 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
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.
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-

10. Processing Evidence: Maintaining the 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
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-

11. Processing Evidence: Maintaining the Chain of Custody from Discovery to Disposal
FINAL DISPOSITION OF EVIDENCE
Evidence must be legally disposed of
Returned to owner
Auctioned
Destroyed
Learning Objective:
Do you know how physical evidence is finally disposed of?
Evidence is either returned to the owner, auctioned or destroyed. 1-

12. Frequently Examined Evidence
FINGERPRINTS
Latent fingerprints
Visible fingerprints
Plastic fingerprints
Dusting latent
fingerprints
Lifting prints
Continued
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.
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-

13. Frequently Examined Evidence (Continued)
FINGERPRINTS
Chemical development
Other methods
Elimination prints
Inked prints
Digital fingerprinting
Continued 1-

14. Frequently Examined Evidence (Continued)
FINGERPRINTS
Fingerprint patterns, analysis and identification
Usefulness of fingerprints
Admissibility in court
Other types of prints
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-

15. Frequently Examined Evidence
VOICEPRINTS
Graphic record made by a sound spectrograph
No two voiceprints are alike
LANGUAGE ANALYSIS
Psycholinguistics
Excited utterances 1-

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
Learning Objective:
Do you know what DNA profiling is?
DNA profiling uses material from which chromosomes are made to identify individuals positively.
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-

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
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-

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
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-

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
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.
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-

20. Frequently Examined Evidence
GLASS
High-velocity versus low-velocity impacts
Glass evidence reference database
SOILS AND MINERALS
Forensic geologists
X-ray diffraction
Microscope
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-

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
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-

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
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-

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
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-

24. Frequently Examined Evidence
LAUNDRY AND DRY-CLEANING MARKS
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
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.
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-

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
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-

26. Frequently Examined Evidence
OTHER TYPES OF EVIDENCE
Learn to read product DNA
Manufacturer codes
Discarded items
Lab can provide collecting and packaging instructions 1-

27. Evidence Handling and Infectious 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 1-

28. Summary
Criminal investigations 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 1-