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Bite Marks

Bite Marks. Often there are bite marks that can be used to identify perpetrators Most often seen in rape, murder, child abuse and spousal abuse Actual pattern varies depending on: Material bitten Presence / absence of teeth Alignment of teeth. Bite Marks.

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Bite Marks

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  1. Bite Marks • Often there are bite marks that can be used to identify perpetrators • Most often seen in rape, murder, child abuse and spousal abuse • Actual pattern varies depending on: • Material bitten • Presence / absence of teeth • Alignment of teeth

  2. Bite Marks Human bite marks vary according to: • Type of tissue bitten • Muscle / connective tissues = distinct • Fat = less distinctive • Biting force • Playful (offensive) bite marks = more distinctive • Aggressive ( defensive) bite marks = less distinct, tearing , bruising, repeated biting • Resistance by victim • Higher resistance = less distinctive • More compliant (or dead) victim = more distinctive

  3. Bite Marks • Bite marks • Deceased vs. Living victims • Useful descriptors related to bite marks on deceased • Time of Death • Response of assailant or victim

  4. Bite Marks Time of Death • Antemortem (pre death) • heart beating = diffuse bruising (spreading) • Agonal / perimortem ( during death ) • Bite marks within 5 minutes of death • Heart is in process of stopping • Well-defined bruising pattern • Postmortem ( after death) • Blood coagulated ( clotted) • Well defined impression • No bruising

  5. Bite Marks

  6. Bite Marks • Offensive bite marks • Well defined pattern • Usually singular pattern • Associated with arousal • Most often post mortem

  7. Bite Marks • Defensive bite marks • Not well defined pattern, possible tearing • Multiple bite patterns • Used as defense against assault

  8. Bite Mark evidence collection • First determine if it is indeed a bitemark (wm3) • Appropriate tools • Dedicated dimensional ruler –all photos • Bite mark kit • Swabbed Three times • Saliva, ABO blood group, amylase • DNA • microorganisms

  9. Bite Mark evidence collection • Photographs • dimensional ruler • dimensions labeled • Varying lights and exposure • Reposition in manner it was inflicted

  10. Bite Mark evidence collection • Due to inflammation, evidence from bite marks on living victims must be obtained within 8 hours, and cannot be washed. They must be photographed multiple times over the next 7 days.

  11. Bite Mark evidence collection • Impressions • Alginate impression material • Add quick set plaster • Cast are made from the impressions • If assailant is available impressions and cast are made • Microscopic analysis • Traces of saliva • microorganisms

  12. Bite Mark evidence collection • Suspect collection • Body search waiver • Court order if necessary • Procedure is outlined to suspect • Every step is photographed and documented • Salivary swabs • Gum swabs • Impressions • Casts

  13. Bite Mark evidence collection • Overlays • Prints are made of bite mark photos • Casts are marked along the biting (occlusal) surface and photographed and printed • Clear plastic sheets are placed over photos and marked • Then overlays are placed over actual bite mark and compared

  14. Bite Mark evidence collection • Overlays • Prints are made of bite mark photos • Casts are marked along the biting (occlusal) surface and photographed and printed • Clear plastic sheets are placed over photos and marked • Then overlays are placed over actual bite mark and compared

  15. Bite Mark Overlays

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