Page 8 - Strands of Evidence Hair And Fiber
P. 8
POST-Lab
Solutions
Truck Collections Evidence Comparison
1. How many distinct types of hair and fiber did 6. How many distinct types of hair and fiber
your lab group recover from the collection were matched from the cabin collections to
tape? samples recovered from the truck (on the
Answers will vary by group. collection tape)?
Answers will vary by class. There should be 3 to
4 types.
2. How many distinct types of hair and fiber
did the class as a whole recover from the
collection tape? 7. What characters did you rely on when
Answers will vary by class. determining if samples were a possible
match?
Answers will vary by student. Color, coarseness,
3. Considering your responses to the previous and twist are commonly cited characters.
two questions, what conclusions about
sampling can you draw?
Depending on the numbers reported, reasonable 8. What can you say about the likelihood of the
conclusions are that a sample will contain many, blanket from the truck being in proximity
but not all, of the types found in the population. to the cabin? Can you express this as a
percent? If so, to what precision? Justify your
response.
Evidence Handling Since several types of fiber were discovered
on both, there is a high liklihood that the
blanket was near the cabin and transfer
4. Why do you believe the samples were sealed occurred. However, since no information on
in the manner they were? fiber frequency exists, all of the fiber types may
The samples were sealed to prevent contamination simply be exceptionally common. Giving any
from sources outside the crime scene.
percent value is misleading because it implies a
degree of certainty where there is none.
5. What reasons can you think of to keep the
two collections separate?
If samples were accidently mixed, spurious
matches would result.
8 THE MYSTERY OF LYLE AND LOUISE
