So you have a crime scene…So you have a crime scene…

Goal: Attain physical evidenceGoal: Attain physical evidence Secure the areaSecure the area Record sceneRecord scene

Rough sketch & photographyRough sketch & photographyAttention to details!Attention to details!

Finish sketchFinish sketchValuable as can add what photos cannotValuable as can add what photos cannot

NotesNotesSystematic search for evidence Systematic search for evidence

What is collected & analyzed?What is collected & analyzed? Victim’s clothingVictim’s clothing Fingernail scrapingsFingernail scrapings Head & pubic hairsHead & pubic hairs Blood (DNA typing)Blood (DNA typing) Vaginal, anal, oral swabsVaginal, anal, oral swabs Recovered bulletsRecovered bullets Hand swabsHand swabs

All must be properly labeled & handled to All must be properly labeled & handled to prevent contaminationprevent contamination Legal ramificationsLegal ramifications Chain of Custody-Chain of Custody- known quantity known quantity

Types of physical evidence:Types of physical evidence:Blood, semen, salivaBlood, semen, saliva

DocumentsDocuments

DrugsDrugs

ExplosivesExplosives

FibersFibers

FingerprintsFingerprints

Firearms & ammoFirearms & ammo

GlassGlass

HairHair

ImpressionsImpressions

Organs and physiological fluidsOrgans and physiological fluids

PaintPaint

Petroleum productsPetroleum products

Plastic bagsPlastic bags

PolymersPolymers

Powder residuesPowder residues

Serial numbersSerial numbers

Soil & mineralsSoil & minerals

Tool marksTool marks

Vehicle lightsVehicle lights

Vegetative matter (location)Vegetative matter (location)

Comparison is the keyComparison is the keyDo the suspect’s specimen match those of the Do the suspect’s specimen match those of the reference specimen?reference specimen? Hair, paint chip, or fiber exampleHair, paint chip, or fiber example

Individual CharacteristicsIndividual Characteristics Evidence that can be attributed to one common Evidence that can be attributed to one common

source w/ high degree of certaintysource w/ high degree of certaintyFingerprintsFingerprints

Bullet markingsBullet markings

Class CharacteristicsClass Characteristics Evidence that can only be associated with a group Evidence that can only be associated with a group

(not a single source)(not a single source)Automobile paintAutomobile paint

Blood typeBlood type