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Physical and biological evidence

Physical and biological evidence. Evidence can be classified as Physical or Biological . Physical evidence usually comes from a non-living origin and includes finger prints , tire tracks , shoeprints and fibers . Biological evidence includes bloodstains and DNA.

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Physical and biological evidence

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  1. Physical and biologicalevidence

  2. Evidence can be classified as PhysicalorBiological. Physicalevidenceusually comes from a non-living origin and includesfingerprints, tire tracks, shoeprints and fibers. Biologicalevidenceincludesbloodstains and DNA. Locard´sexchangeprinciplestatesthatperpetratorsalwaysleavephysical and biologicalevidence at thescene of thecrime, and takesomethingawaywiththem. Suchevidenceisusuallyfound in verysmallquantities, and iscalledtrace evidence.

  3. Whateverevidenceisfound, itis vital to establish a securechain of custody. Eachpersonhandlingtheevidencefromitscollection to itsappearance in courtmustsignforit. Itisimportantthatevidenceisnotcontaminated. Itmust be preservedcarefully, sinceitemsmaydeteriorateifthereis a longintervalbeforethe criminal trial begins.

  4. Somekind of physicalevidencesuch as tire tracks and shoeprints are notenough to convict, becausethey do notprovetheindividual´sinvolvement. Thistype of evidenceisknown as classevidence. Classevideceisvaluableifseveraldifferenttypes of evidence can be foundtogether. Forexample, findingvariousfibers and shoeprintsis more valuablethanfindingonlyeonefiber. Thenthey can be combined to identifytheperpetrator.

  5. 1 DNA is a kind of (biological / physical) evidence 2 Themanleft (fingerprints / tire marks) when he touchedthewindow 3 Evidencemust be (contaminated / preserved) orelseitwillnotlastuntilthe trial 4 Thepoliceneed more (trace / class) evidence to convictthesuspect

  6. 5 The (fibers / bloodstains) camefrom a wooljacket 6 Investigatorswearprotectiveclothing to avoid (preserving / contaminating) evidence

  7. 1 Didtheinvestigatorsfindanyphysicalevidence? A Yes, therewereshoeprintsunderthebrokenwindow B No, thechain of custody has notbeenestablished. 2 What trace evidencewasfound in thesuspect´s home? A Thecoldweatherhelped preserve thecrimescene B Thepolicefoundmudfromthecrimescene in hisapartment

  8. 3 Why are tire tracks so important to the case? A Thepaintonthe car matchestheonethatlefttheaccident B They can be traced back to the tires onthesuspect´svehicle 4 How do thepoliceknowtheperpetrator has brownhair? A Theyfoundseveralhairs at thescene of thecrime B Theevidence shows he wears a size 11 shoe

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