Postmortem - Lecture 15

Question 1

What is postmortem trauma?

Answer 1

• damage to the bone occurring after death
• can be human induced or naturally occurring
• tells a story of activities after death

Question 2

What is recovery damage? How can you tell if it’s postmortem trauma or recovery damage?

Answer 2

• when bone is damage when being recovered/excavated
• if its recovery damage, the damaged area will be lighter than the rest

Question 3

Name two postmortem human activities.

Answer 3

• trophy taking like scalping
• dismemberment

Question 4

What are the two types of dismemberment?

Answer 4

1. Localized Dismemberment
   - removing identifying body parts like hands
   - aid in disposal (cutting below natural joints)
2. Generalized Dismemberment
   - dismembering the body at natural joints
   - lots of skill and time required

Question 5

What are the 3 kinds of instruments of dismemberment?

Answer 5

1. knives
   - incisions at joints (generalized dismemberment)
2. axes
   - causes clefts and wastage (localized dismemberment)
3. saws
   - most efficient and useful
   - leave identifying features on what type of saw was used

Question 6

What are the two types of saws?

Answer 6

1. hand saw
2. power saw
   - straight or circular
   - table

Question 7

What is a kerf?

Answer 7

• the space left behind from the cut of a saw
• tells you a lot about the type of saw being used

Question 8

What are the two different types of blades (teeth design) on a saw?

Answer 8

1. fine
   - smaller teeth
   - more of them and closer together
2. coarse
   - larger and fewer teeth
   - set further apart

Question 9

Why is the kerf important?

Answer 9

• 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

Question 10

How is the kerf floor made?

Answer 10

when someone gets tired and breaks the bone the rest of the way after sawing for half of it

Question 11

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?

Answer 11

• 1.5 times wider because of the crosscut of the blade
• divide the width of the kerf by 1.5

Question 12

Power saws produce _____ striations, hand saws produce ____ striations

Answer 12

• uniform and fine
• irregular and prominent

Question 13

Why is the kerf wall important?

Answer 13

striations left behind can show if a power or hand saw was used

Question 14

What is a breakaway spur? What can they help identify?

Answer 14

• 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)

Question 15

What are the 3 kinds of marks caused by saws on bone? Describe them.

Answer 15

1. superficial scratches
   - scratches on the bone when you’re lightly dragging the saw across the bone
   - no kerf being left behind
2. 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
3. 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

Question 16

What are the first two steps of analyzing saw marks?

Answer 16

1. basic description
   - everything you see
   - number of false starts, sectioned cuts, superficial scratches
2. direction of saw cut
   - of the progress and stroke

Question 17

What are the third and fourth steps of analyzing saw marks?

Answer 17

3. general tooth size and number
4. blade width

Question 18

What are the fifth and sixth steps of analyzing saw marks?

Answer 18

5. 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)
6. source of energy
   - hand or power saw

Question 19

How can you determine if the dismemberment was human or animal?

Answer 19

• 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