Postmortem - Lecture 15 Flashcards
What is postmortem trauma?
- damage to the bone occurring after death
- can be human induced or naturally occurring
- tells a story of activities after death
What is recovery damage? How can you tell if it’s postmortem trauma or recovery damage?
- when bone is damage when being recovered/excavated
- if its recovery damage, the damaged area will be lighter than the rest
Name two postmortem human activities.
- trophy taking like scalping
- dismemberment
What are the two types of dismemberment?
- Localized Dismemberment
- removing identifying body parts like hands
- aid in disposal (cutting below natural joints) - Generalized Dismemberment
- dismembering the body at natural joints
- lots of skill and time required
What are the 3 kinds of instruments of dismemberment?
- knives
- incisions at joints (generalized dismemberment) - axes
- causes clefts and wastage (localized dismemberment) - saws
- most efficient and useful
- leave identifying features on what type of saw was used
What are the two types of saws?
- hand saw
- power saw
- straight or circular
- table
What is a kerf?
- the space left behind from the cut of a saw
- tells you a lot about the type of saw being used
What are the two different types of blades (teeth design) on a saw?
- fine
- smaller teeth
- more of them and closer together - coarse
- larger and fewer teeth
- set further apart
Why is the kerf important?
- as the blade slices through bone it will leave marks on the kerf wall that will either be smoother indicating a fine blade or rougher indicating a coarse blade
- can also tell by the floor of the kerf which would have imprint of the saw
How is the kerf floor made?
when someone gets tired and breaks the bone the rest of the way after sawing for half of it
How much larger in width will the kerf be than the actual blade width? Why? How do you determine get the width of the blade?
- 1.5 times wider because of the crosscut of the blade
- divide the width of the kerf by 1.5
Power saws produce _____ striations, hand saws produce ____ striations
- uniform and fine
- irregular and prominent
Why is the kerf wall important?
striations left behind can show if a power or hand saw was used
What is a breakaway spur? What can they help identify?
- bottom of the cut breaking away due to the weight of the object being cut
- can help identify the direction of the cut (the starting point of cutting is opposite from the breakaway spur)
What are the 3 kinds of marks caused by saws on bone? Describe them.
- superficial scratches
- scratches on the bone when you’re lightly dragging the saw across the bone
- no kerf being left behind - false starts
- small kerf being left behind
- trying to begin cutting the material but having a hard time and remove the blade and start somewhere else - sectioned bone cut
- can measure the kerf to get the blade width very accurately from this because the kerf is intact
- not a full cut
What are the first two steps of analyzing saw marks?
- basic description
- everything you see
- number of false starts, sectioned cuts, superficial scratches - direction of saw cut
- of the progress and stroke
What are the third and fourth steps of analyzing saw marks?
- general tooth size and number
- blade width
What are the fifth and sixth steps of analyzing saw marks?
- blade shape
- fixed radius striae which is a circular saw (all striae have the same orientation throughout the kerf wall)
- nonfixed-radius striae which is a straight blade (orientation of striae wil vary) - source of energy
- hand or power saw
How can you determine if the dismemberment was human or animal?
- humans don’t remove scapulae and clavicles, just humerus
- humans don’t remove the femur from the acetabulum, they just cut through it instead
- humans don’t separate parts of the thorax, they keep it intact
