Physical Evidence

1
Physical Evidence
2
Common Types of Physical Evidence

1. Blood, Semen, and Saliva
2. Documents
3. Drugs
4. Explosives
5. Fibers
6. Fingerprints
7. Firearms and Ammunitions

3
Common Types of Physical Evidence

1. Glass
2. Hair
3. Impressions
4. Organs and Physiological Fluids
5. Paint
6. Petroleum Products
7. Plastic Bags

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Common Types of Physical Evidence

1. Powder Residues
2. Serial Numbers
3. Soil and Minerals
4. Tool Marks
5. Vehicle Lights
6. Wood and other Vegetative Matter

5
The Examination of Physical Evidence

• Identification
• Comparison

6
Identification

• Determination of physical and chemical identity
  of a substance (to the exclusion of all other
  substances) with as near absolute certainty as
  existing analytical techniques will permit.
• - Drugs - Gasoline Residues
• - Explosive Residues - Blood, Semen, Hair

7
Comparison

• Analysis that subjects a suspect specimen and a
  control specimen to the same tests and
  examinations for the ultimate purpose of
  determining whether or not they have a common
  origin.
• 1. Individual Characteristics
• 2. Class Characteristics

8
Individual Characteristics

• Evidence that can be associated with a common
  source with an extremely high degree of
  probability.
• -Fingerprints 1 in 1x1060 probability of two
  being the same
• -Tool Marks
• -Bullets

9
Class Characteristics

• Evidence that can be associated only with a group
  and never with a single source.
• -paint chips
• -blood type (Type A 26)
• -fibers
• -hairs

10
Crime-Scene Reconstruction

• It supports a likely sequence of events by the
  observation and evaluation of physical evidence,
  as well as statements made by witnesses and those
  involved with the incident.

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Crime-Scene Reconstruction

• The following questions must be answered
• -Was there more than one person involved?
• -How was the victim killed?
• -Were there actions taken to cover up what
  actually took place?

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Crime-Scene Reconstruction

Law Enforcement Personal
Medical Examiner
Crime-Scene Reconstruction
Criminalist
13
The Wayne Williams Trial

• Atlantas Missing and Murdered Children Case
• (July 1979 May 1981)

14
Case Background

• 30 missing and murdered black children and black
  young men during the 22-month period.
• Those found had died of asphyxiation.
• Investigators noticed unusual yellow-green nylon
  fibers and violet acetate fibers on many of the
  victims.
• The fiber findings were reported in February
  1981, after which the victim were found unclothed
  or in undershorts.

15
The Yellow-Green Nylon Fibers

• Very coarse
• Lobed cross-sectional appearance
• Possibly from a carpet or rug
• Not readily recognized by industry experts

16
James Jackson Bridge

• May 22, 1981 Atlanta P.D. and the FBI carry out
  a night time surveillance.
• Chicago Sun Times

17
James Jackson Bridge

• 200 am- They hear a loud splash and observe an
  automobile being driven slowly across the bridge.
• The driver was stopped and identified to be Wayne
  Bertram Williams.
• Two days later, Nathaniel Caters body was pulled
  from the Chattahoochee River.

18
Building a Case

• July 1981 Wayne Williams was charged with the
  murders of Nathanial Cater and Jimmy Payne.
• Evidence included
• Fibers, Hairs, and Bloodstains
• Presence on the James Jackson Bridge
• Known Relationships with the victims

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The Williams Bedroom Carpet

• Made of yellow-green fiber matching that found on
  the victims.
• Fibers were manufactured by the Wellman
  Corporation 1967 1974.
• West Point Pepperell Corporation of Dalton,
  Georgia used the fibers to make Luxaire carpet
  from 12/1970 to 12/1971.

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Probability Determinations

• West Point Pepperell reported purchases of
  Wellman 181B fiber during a 1-year period. The
  Wellman 181B fiber used to manufacture Luxaire
  carpet from 12/1970 until 12/1971, at which time
  a new fiber type replaced that Wellman fiber.

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Probability Determinations

• In 1971, West Point Pepperell sold 5,710 square
  yards of English Olive Luxaire and Dreamer
  carpet in the Southern Region (10 states). In
  order to account for the carpet manufactured
  during 1971, but sold after that time, all the
  Luxaire dyed English Olive in color during 1972
  to the Southern Region (10,687 square yards)
  added to the 1971 sales. Total 16,397 square
  yards. (In 1979, existing residential carpeted
  floor space in the United States was estimated at
  6.7 billion square yards.

22
Probability Determinations

• By assuming that this carpet was installed in one
  room, averaging 12 feet by 15 feet in size, per
  house, and also assuming that the total sales of
  carpet were divided equally among the 10 Southern
  States, then approximately 82 rooms with this
  carpet could be found in the State of Georgia.

23
Probability Determinations

• Information from the Atlanta Regional Commission
  showed that there were 638,995 occupied housing
  units in the Atlanta metropolitan area in
  November 1981. Using this figure, the chance of
  randomly selecting an occupied housing unit in
  the Atlanta metropolitan area and finding a house
  having carpet like the Williams carpet was
  determined to be 1 chance in 7,792 a very low
  chance!

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Other Fibers Linking Williams to the Victims
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February 26, 1982

• A Fulton County, Ga., Superior Court jury
  returned a verdict of guilty as charged on two
  counts of murder brought against Wayne Bertram
  Williams.
• The Atlanta Journal and Constitution

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