Crime Scene and Evidence Collection. Vocabulary to Know First responder Individual evidence Paper...

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Crime Scene and Evidence Collection

Transcript of Crime Scene and Evidence Collection. Vocabulary to Know First responder Individual evidence Paper...

Crime Scene and Evidence

Collection

Vocabulary to Know

• First responder• Individual evidence• Paper bindle• Primary crime scene• Secondary crime

scene• Trace evidence• Direct evidence

• Chain of Custody• Circumstancial

evidence• Class evidence• Crime scene

investigation• Crime scene

reconstruction

Types of Trace Evidence

• Hair

• Fibers

• Skin cells

• Pollen

• Glass fragments

• Paint chips

• Makeup, etc.

Classifying Evidence

• Direct Evidence:• 1st hand observations;

eyewitness video.

• Circumstancial evidence:• Indirect evidence

implies fact but doesn’t prove.

• 2 types – physical and biological

Classifying Evidence - Circumstancial

• Biological (more pursuasive)• Body fluids

• Hair

• Plant parts

• Natural fibers

• Blood

• Physical• Impressions

• Fingerpints, shoeprints, tire prints,tool marks.

• Synthetic fibers

• Shell casings

• Bullets

• Weopons

Also called Indirect Evidence

Classifying Evidence

• Class Evidence

• Place evidence into groups. Make or model or objects

• Individual Evidence

• Place evidence to an individual person or thing.

Let’s Do a LabCan Evidence be Individualized?

• Purpose: to determine whether pieces of evidence are class or individual evidence.

• Procedure: • Separate into groups of two.

Each group go to a lab table. 1-15

• Rotate through the scenarios until you have completed all.

• Time: 3 mins @ each table

• Expectations:• Work only with your lab

partner. Do not move through groups.

• Stay at your current lab table until told to rotate.

• I will know you are participating by you being actively engaged in the lab.

• Failure to follow lab safety and the above expectations will result in 3 point deducted off each lab members grade.

Locard’s Exchange Principle

• Established by

Dr. Edmond Locard• Director of 1st forensic lab

in Lyon, France.

• States: when a person comes in contact with an object or another person, a cross-transfer of physical evidence occurs. The evidence is known as trace evidence.

• "It is impossible for a criminal to act, especially considering the intensity of a crime, without leaving traces of this presence."

CSI (Crime Scene Investigation)

CSI Team

• Police officers• CSI

• Recorders, sketch artists, photographers, evidence collectors.

• ME (medical examiner)• Detectives• Specialists

• Entomologist, psychologists, anthropologists

7 S’s of CSI

• Secure crime scene

• Separate witnesses

• Scan scene

• Seeing the scene

• Sketch the scene

• Searching for evidence

• Securing and collecting evidence

7 S’s: Secure the Crime Scene

• Done by 1st responder• Restrict all unauthorized

persons from entering cs.

• Keep security log of all who visit cs.

• Keep evidence from getting contaminated.

7 S’s: Separating Witnesses

• Keep witnesses from comparing or creating a story (collusion).

• Ask each witness the following ?’s.

1.when did the crime occur?

2.Who called in the crime?

3.Who is the victim?

4.Can the perp. be identified?

5.What did you see happen?

6.Where were you when you observed the crime?

7 S’s: Scanning the Scene

• Scan scene to determine where photos need to be taken.

• May occur at both primary & secondary cs.

7 S’s: Seeing the Scene

• CS examiner must see (observe) the scene.

• Photos must be taken w/ & w/o measuring ruler.

• Triangulation of stationary obj. should be included as reference pts.

• View cs from several different angles.

7 S’s: Sketching the Scene• Rough Sketch• Should include:a. Position of any evidence or victim.

b. All objects measured from two stationary landmarks

c. North labled

d. Scale of distance provided

e. Any objects in vicinity of cs. (doors, windows, furniture)

f. If outdoors, position of trees, vehicles, hedges, and other structures should be included.

• Final Sketch• Very accurate;

could be used in court.

• In addition to RS include:

a. Case #

b. Date

c. Location

d. Name

Sketch Examples

7 S’s: Searching for Evidence

• Search patterns:a. Grid

b. Linear

c. Quadrant or Zone

d. Spiral

• Single investigater may use grid, linear or spiral.• Group – linear, zone or quadrant.• Flashlight & forceps are equipment of choice.

Keeps from picking up extraneous materials.

Types of Search Patterns

7 S’s: Securing & Collecting

• Must be properly packaged, sealed & labeled1. Packaging Examples:

• Liquids & arson: stored in airtight, unbreakable containers• Most biologicals: breathable containers so evidence can

dry out – reduces chance of mold contamination. Package in paper bindles.

• Once proper containers are used, place in plastic or paper container. Then:

a. Seal with tape.

b. Label across tape by collector

c. Evidence log & chain of custody attached to evidence container.

7 S’s: Securing & Collecting

2. Evidence Log includes:a. Case #

b. Item inventory #

c. Description of evidence

d. Name of suspect

e. Name of victim

f. Date & time of recovery

g. Signature person recovering evidence

h. Signature of any witness present during collection.

7 S’s: Securing & Collecting

3. Packaging EvidenceA. Choose appropriate size

sheet of clean paper for bindle.

B. Crease paper in grid pattern

C.Place evidence in center grid

D.Fold in left then right sides

E. Fold over top & bottom

F. Insert top flap into bottom flap & tape closed.

G. Place bindle inside plastic/paper bag. Fold bag closed.

H. Place seal over folded edge of evidence bag.

I. Collector writes name over folded edge.

Remember: large, wet object should be placed in paper container & sealed to allow for air drying.

Control samples must also be taken from victim for the purpose of exclusion.

Chain of Custody*Very Important*

• Individual that finds the evidence marks it for identification & bags evidence in plastic/paper container.

• Placed in final container & labeled with pertinent info.

• Container is sealed & collectors signature across sealed edge

• Pass onto person that will transport to lab who signs it over to technichian.

• Tech opens packaging at some other location except where originally sealed.

• After examination, evidence is repackaged in original container where it was removed & placed in a new package.

• Seal new packaging with techs signature on seal.

• Tech also signs chain of custody log attached to package.

Analyzing Evidence

• processed by tech that specializes in specific areas of forensic science

• Evidence results sent to lead detective

• Crime Scene Reconstruction• Crime scene reconstruction

completed using evidence (before crime to its completion)

• Evidence used to co-oberate witness accounts

• Direct evidence more compelling than circumstancial.

• Staged Scenes• Poses unique problems. Evidence

doesn’t match witness testimony.

• Common staging situations.

Staged Crime Scene