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The Crime Scene
http://www.freefoto.com/preview/283110?ffid=283110&k=Crime+Scene+Do+Not+Enter
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Enduring understanding:
Properly evaluating a crime scene and collecting evidence is a crucial step in forensic science.
Detailed observations are vital to the work of a forensic scientist.
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Essential Questions:
What happens once a crime scene is found?
How is a crime scene processed?
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Crime scene= any place where evidence may be located to help explain events
information gathered helps to:
reconstruct the sequence of events determine modus operandi the characteristic method of operation of a criminal (their MO) determine motive for crime
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Steps taken when a crime scene is found
**first officer on scene must preserve and protect the area1. get medical assistance for injuries, call coroner if needed.
2. Exclude all unauthorized personnel
3. Witnesses and suspects are detained separately
4. secure the area by establishing perimeters (crime scene tape)
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5. Lead investigator evaluates areadetermines boundariesperpetrator's entrance and exit
6. Scene is recordeda.notes
complete and thorough, clear and legibledetails actions taken by investigator in sequencemeasure the scene, and refer to it in
describing evidence and where founddate/time, location, weather, environmental conditionsdescription of crimelocation of evidence relative to other
pointsname of people involved (personnel,
witnesses, victims)all changes that occur
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b. photographs
Nicole Brown Simpson
http://www.bobaugust.com/photo.htm
may capture detailsdone before evidence
removedentry/exit points
closeup photos of evidencephotos of scene through eyes of witnesslocation of the scene and surroundingsobjects from different anglesinclude rulers for scalevideotape with narration (should not be edited or erased)
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http://www.feinc.net/crime4.gif
c. Sketcheshelp to notice and remember detailsshow relationships of points of interestshows overal layoutgives measurements,scale, reference points
date/timescaledistance measurementsinvestigator namevictimssuspects, a legend
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rough sketch a sketch, drawn at crime scene, contains accurate dimensions of scene and location of all objects (p. 47 in text)
shows distances from two pointsassign objects numbers or lettersneed legend
finished sketch a precise rendering of crime scene, drawn to scale (p. 48 in text)
CAD
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7. Search the scene for physical evidencethorough and systematicidentifypackagelabeling evidenceUV light body fluidscan subdivide large areas make grid
move parallel and then from different directionor spiral searches/quadrantscan vacuum area / packaged separatelyfingernail scrapings
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8. collect and package evidenceeach piece goes in separate containerall containers labelledmost fragile collected first (fingerprints, bloodstains, etc.)Whole garments collectedwet items dried before packagingtightly seal containersbiological items dried and frozenclothing packaged carefullyfirearms fixed in wooden containerarson evidence in airtight container so no evaporationvacuumadhesive tape
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9. Maintain chain of custody a written record of all people who have had possession of an item of evidence
collector's initials, location of evidence, date of collectionanyone who is involved in collection and transportation may have to testify in court
10. Collect controls (standards/reference samples)used for comparisonsubstrate controls uncontaninated surface material close to area where physical evidence is found
to make sure does not interfere with lab tests
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11. Submit evidence to labpersonal delivery or mailevidence submission formprovide lab with brief case history