Physical Evidence. Common Types of Physical Evidence 1. Blood, Semen, and Saliva 2. Documents 3. Drugs 4. Explosives 5. Fibers 6. Fingerprints 7. Firearms

Physical EvidencePhysical Evidence

Common Types of Physical EvidenceCommon Types of Physical Evidence

1. Blood, Semen, and Saliva

2. Documents

3. Drugs

4. Explosives

5. Fibers

6. Fingerprints

7. Firearms and Ammunitions


8. Glass

9. Hair

10. Impressions

11. Organs and Physiological Fluids

12. Paint

13. Petroleum Products

14. Plastic Bags


15. Powder Residues

16. Serial Numbers

17. Soil and Minerals

18. Tool Marks

19. Vehicle Lights

20. Wood and other Vegetative Matter

The Examination of Physical The Examination of Physical EvidenceEvidence

Identification

Comparison

IdentificationIdentification

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

ComparisonComparisonAnalysis 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

Individual CharacteristicsIndividual 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

Class CharacteristicsClass 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

Crime-Scene ReconstructionCrime-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.


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?


Crime-SceneReconstruction

LawEnforcement

Personal

MedicalExaminer

Criminalist

The Wayne Williams TrialThe Wayne Williams Trial

Atlanta’s Missing and Murdered Children Case

(July 1979 – May 1981)

Case BackgroundCase 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.

The Yellow-Green Nylon FibersThe Yellow-Green Nylon Fibers

Very coarseLobed cross-sectional appearancePossibly from a carpet or rugNot readily recognized by industry experts

James Jackson BridgeJames Jackson Bridge

May 22, 1981 – Atlanta P.D. and the FBI carry out a night time surveillance.

Chicago Sun Times

James Jackson BridgeJames Jackson Bridge

2:00 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 Cater’s body was pulled from the Chattahoochee River.

Building a CaseBuilding 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

The Williams’ Bedroom CarpetThe 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.

Probability DeterminationsProbability 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.


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.


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.


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!

Other Fibers Linking Williams Other Fibers Linking Williams to the Victimsto the Victims

February 26, 1982February 26, 1982A 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