More Crime Scene Info
Forensic Science
10/1/14
Drill
•What should the first officer on thescene of a crime do?
•What should the forensic scientistdo, once they get there?
•HW: Ch 2 Qs
–Cross out #5
–Do #6-10
Objectives
•IWBAT
–Describe the proper techniques forpackaging common types of physicalevidence.
–Define the chain of custody.
–Define the terms Rigor Mortis, LivorMortis and Algor Mortis.
Agenda
•Drill
•Finish Chapter 2 Notes
•Start online investigation
•Closure
Packaging
•Each different item or similar itemscollected at different locations must beplaced in separate containers.Packaging evidence separately preventsdamage through contact and preventscross-contamination.
•The well-prepared evidence collectorwill arrive at a crime scene with a largeassortment of packaging materials andtools ready to encounter any type ofsituation.
Packaging
•Forceps andsimilar tools mayhave to be used topick up smallitems.
•Unbreakableplastic pill bottleswith pressure lidsare excellentcontainers forhairs, glass, fibers,and various otherkinds of small ortrace evidence.
Packaging
•Alternatively, manila envelopes,screw-cap glass vials, or cardboardpillboxes are adequate containers formost trace evidence encountered atcrime sites.
•Ordinary mailing envelopes shouldnot be used as evidence containersbecause powders and fine particleswill leak out of their corners.
Packaging
•Small amounts of trace evidence canalso be conveniently packaged in acarefully folded paper, using what isknown as a “druggist fold” or“bindle.”
What’s a bindle?
1.Crease a clean paperand place evidence inthe X position
2.Fold in the left andright sides, and thenfold in the top andbottom
3.Put the bindle into aplastic or paperevidence bag affixinga seal over theopening
4.Write your name onthe seal
Forensic Science: Fundamentals &Investigations, Chapter 2
11
Packaging
•Although pill bottles, vials, pillboxes,or manila envelopes are gooduniversal containers for most traceevidence, one frequent find at crimescenes warrants special attention.
Packaging
•If bloodstained materials are storedin airtight containers, theaccumulation of moisture mayencourage the growth of mold,which can destroy the evidentialvalue of blood.
•In these instances, wrapping paper,manila envelopes, or paper bags arerecommended packaging materials.
Add this…
•Any materials that have gasoline orother flammable liquids on themMUST be stored in metal, air-tightcanisters.
•Otherwise, the fumes may interactwith plastic, or evaporate.
Chain of Custody
•Chain of Custody—A list of all personswho came intopossession of anitem of evidence.
•Continuity ofpossession, or thechain of custody,must be establishedwhenever evidenceis presented incourt as an exhibit.
Chain of Custody
•Adherence to standard procedures inrecording the location of evidence,marking it for identification, andproperly completing evidencesubmission forms for laboratoryanalysis is critical to chain of custody.
•This means that every person whohandled or examined the evidence andwhere it is at all times must beaccounted for.
Obtaining Reference Samples
•Standard/Reference Sample—Physicalevidence whose origin is known, such asblood or hair from a suspect, that can becompared to crime-scene evidence.
•The examination of evidence, whether it issoil, blood, glass, hair, fibers, and so on,often requires comparison with a knownstandard/reference sample.
•Although most investigators have littledifficulty recognizing and collecting relevantcrime-scene evidence, few seem aware ofthe necessity and importance of providingthe crime lab with a thorough sampling ofstandard/reference materials.
Special Forensic ScienceServices
•Forensic Pathology involves theinvestigation of unnatural,unexplained, or violent deaths.
–Forensic pathologists in their role asmedical examiners or coroners arecharged with determining cause of death.
–The forensic pathologist may conduct anautopsy which is the medical dissectionand examination of a body in order todetermine the cause of death.
Special Forensic ScienceServices
•After a human body expires there are severalstages of death.
–Rigor mortis results in the shortening of muscletissue and the stiffening of body parts in theposition at death (occurs within the first 24 hrs.and disappears within 36 hrs.).
–Livor mortis results in the settling of blood inareas of the body closest to the ground (beginsimmediately on death and continues up to 12hrs.).
–Algor mortis results in the loss of heat by a body(a general rule, beginning about an hour afterdeath, the body loses heat by 1 to 1 1/2 degreesFahrenheit per hour until the body reaches theenvironmental temperature).
Examining a Crime Scene!
•We will be examining a Crime Scene,online. You are playing as a policeofficer, with your group.
•Your group is a group of no more than5 students at one computer. Chooseyour group wisely.
•One sheet per group
•As you go to each scene, make sureyou click on the picture to gatherevidence.
Closure
•You may work on the Chapter 2Questions