Chapter 2- Crime Scene Investigation and Evidence Collection(modern marvel- FBI crime lab)

Types of Evidence

Direct:– 1st hand observations that may/may not prove

an alleged act

Circumstantial:– Indirect evidence , used to imply a fact but not

prove it directly, can be physical or biological

Trace Evidence:– Small but measurable quantities of physical or

biological material found at scene

Locard Exchange Principle: when a person comes into contact with an object or another person, a cross-transfer of trace evidence can occur

Common Forms of Physical Evidence

(Note: the weight of physical evidence is left up to the jury)

1. Blood, semen, saliva

2. Documents

3. Drugs

4. Explosives

5. Fibers

6. Fingerprints

7. Firearms and ammunition/ powder residue

8. Glass

9. Hair

10. Impressions (bite/tire/shoe)

11. Organs and physiological fluids

12. Paint

13. Petroleum Products

14. Plastic bags/polymers

15. Serial Numbers

16. Soil

Purpose of Evidence

1. Identification– Determine a substance’s physical or

chemical identity– Determine what species it came from

2. Comparison Compare evidence to other objects to see if

they have the same origin Each evidence type has a specific # of

properties that must match

Types of Characteristics

1. Individual Characteristics Properties of the evidence that can be

attributed to a source w/ high degree of certainty

Ex. Ridges on fingerprints, striations on bullets, wear patterns on shoes/tires

Types of Characteristics

2. Class Characteristics Occurs when evidence is associated w/ a

group, not a single source Chance of finding class evidence is greater Use class evidence to corroborate events Ex. Type of fiber, type of soil

Steps of Evidence Collection

1. Secure and Isolate the Crime SceneEnsure no destruction of evidenceObtain medical assistance (if needed)(every individual who enters the scene

is a potential destroyer of evidence)Separate any witnesses and questionSet up primary and secondary crime

scenes

2. Record the Scene*Photography

Done before any other workPhotograph before anything is

removedPhotograph all areas of scene and

surroundingsUse frame of reference in picture

(ruler, coin)

*Sketches

CSI does rough sketchGives dimensions, shows location of all

important objects (with legend below sketch)

Measure distance from fixed pointsShows northFinish sketch-CAD design (for court,

precise)

*Notes

Detailed written description of scene

Includes who discovered pieces of evidence, time, how it was collected

Can be tape recorded

3. Conduct a systematic search for evidence

Done by CSI or field evidence technician

Examine for fingerprints, foot prints, tool marks, hair, fibers, etc.

How one proceeds depends on the size of the scene

4.Collect and package physical evidence

Evidence must be handled and processed in a way that prevents any change from taking place (ex. Arson- air tight container)

Assure no:contamination, breakage, evaporation, scratching, bending

All items are packaged separatelyTools used: forceps, pill bottles, glass vial,

manila envelopes

5. Maintain the chain of custody

Keep a list of all persons who come into possession of an item of evidence (this is presented in court) and witnesses to the collection

Includes: case number, description, name of suspect/victim and date/time of collection

6. Obtain controls

Obtain physical evidence of known objects

Used as a standard for comparison or elimination of suspects

Ex. Blood/hair from suspect and victim

7. Submit evidence to laboratory

Bring to crime lab personally or mailMust include a “request for

examination” (so the crime lab knows what to look for- don’t want them doing drug analysis on something you wanted them to test for DNA on)

8. Analysis of evidence

Four Federal Crime Labs– Federal Bureau of Investigation (FBI)– Drug Enforcement Agency (DEA)– Bureau of Alcohol, Tobacco, and Firearms

(ATF)– United States Postal Inspection Service

8. Analysis of evidence

Basic Services Provided:– Physical Science Unit

– Biology unit

– Firearms Unit

– Document Examination

– Photography Unit

Other Services:– Toxicology Unit

– Latent Fingerprint Unit

– Polygraph Unit

– Voiceprint Analysis Unit

– Evidence Collection Unit

Legal Considerations at the Crime Scene

Fourth Amendment Privilege

Right of people from “unreasonable search and seizure”

Warrantless search allowed if:1. Existence of emergency2. It is needed to prevent loss/destruction of evidence3. Search of person/property w/in immediate control

of person in lawful arrest4. Search made by consent of parties involved

5. Newtown warrants Adam Lansa

2. Mincey v. Arizona -1978

Legality of police raid of drug dealer-ended w/ cop killed

Police searched dealers house for 4 days with out warrant

Supreme court upheld 4th ammend.- even it was serious-evidence not admitted

3. Michigan v. Tyler- 1978

Entry to a fire requires NO warrant

Site can be investigated for a reasonable time after fire (but additional re-entries need warrant)

Guides to Collection of Evidence

NOTE: When time and circumstances permit, obtain a search warrant b/4 investigating and retrieving physical evidence from a crime scene

Collecting evidence

On Saturday January 6, 2007 Hugh Christopher Newsom, age 23 and Channon Gail Christian, age 21, both students at the University of Tennessee went out on a date. They were driving in Channon's Toyota 4-Runner when they were carjacked at gunpoint. Suddenly the crime turned far more savage than an armed car theft. Chris and Channon were kidnapped and driven to 2316 Chipman Street where they were forced into the home at gunpoint. While Channon was forced to watch, her boyfriend was raped prison style and then his penis was cut off. He was later driven to nearby railroad tracks where he was shot and set afire. But Channon's hell was just beginning. She was beaten; gang raped repeatedly in many ways, had one of her breasts cut off and bleach poured down her throat to destroy DNA evidence-all while she was still alive. To add to Channon's degradation the suspects took turns urinating on her. They too set her body afire, apparently inside the residence, but for some reason left her body there-in five separate trash bags...

Walk through of Crime Scene newstory http://en.wikipedia.org/wiki/Murders_of_Channon_Christian_and_Christopher_Newsom

Documenting a crime sceneCollecting evidenceTrace evidence- hair and fiber