Forensics – Unit 2 Review Sheet
Fingerprints
1. List the three types of fingerprints that could be found at a crime scene.
a. _____visible_____________________________________________
b. __________plastic________________________________________
c. _______________latent___________________________________
2. Are fingerprints considered class or individual evidence? Why or why not?
fingerprints are considered class evidence until you incorporate minutia making them individual
3. Ridge characteristics can be found on what three areas of the body?
a. ______ear____________________________________________
b. ________feet__________________________________________
c. ___________hands or fingers
d. lips____________________________
4. What are the three main types of fingerprint patterns?
a. ___loop_______________________________________________
b. _______arch___________________________________________
c. __________whorl________________________________________
5. Which pattern is the most common one found in the population? ______loop_____________
6. Which pattern is the least common one found in the population? __________arch (tented)_________
7. True or False: Fingerprints change over time on an individual? ____False_______________
8. The Primary Henry Classification identifies the presence of _whorl__________ patterns on fingers and
each finger is assigned a number based on the presence or absence of that pattern on that particular
finger.
9. The Secondary Henry Classification is used to calculate the ___probability________ of a particular
fingerprint pattern on a finger in the population.
10. What type of classification is used to match an unknown print to a known print?
___________minutia________________________________
11. What are minutiae? How are they used in fingerprint ID?
________small details in the print, type of minutia and location of the minutia__
12. Why is hair important evidence (hint: think about its structure).
___has many characteristics and is very common b/c it falls out often (telogen hairs)___________
13. Is hair considered class or individual evidence? Why or why not?
___________Class evidence, if it is pulled out and has a follicular tag which has blood which may have DNA it
can become individual_____________________________
14. How can hair and fibers have probative value?
__Use frequencies of fiber and hair characteristics to apply to possibility of reoccurrence in the population__
15. Hair morphology (label the different parts of a hair):
A
B
C
i. Cuticle - C
ii. Medulla - A
iii. Cortex - B
16. Which part of the hair contains the pigment?
__cortex__________________________________
17. What protein is hair mainly composed of? _________keratin_____________________
18. What are some structural ways in which human hair differs from the hair of other mammals?
_____narrow medulla, less than a third of the total hair diameter, human < 1/3 and animal >1/2 __________
19. Draw the cross sectional shapes of hair: Round, Oval, and Crescent.
20. Why would it be risky to assign race to a suspect based on this characteristic. ___biracial individuals or
a person with uncharacteristic hair for their race. (EX. European person with really curly hair)_______
21. True or False: Medulla patterns vary among individuals and among hairs of an individual? _________
22. Three growth phases of hair are anagen, catagen, and telogen. At which phase would hair be least
likely to have a follicular tag (composed of skin and blood cells) if it was pulled out? Why would a
follicular tag be important for a crime investigation? _follicular tags have DNA___________
23. How can hair be a chemical indicator or how can one get a false positive from a hair sample?
_____may get drug residue on hair from being around drugs without using drugs…__________
24. What are the two main types of fibers – give examples of each.
a. __synthetic- rayon________________________________________________
b. _______________natural-cotton___________________________________
25. Are fibers considered class or individual evidence? Why or why not?
Class evidence because they only bring you to a type of fabric or a manufacturer
26. Synthetic fibers are made of __polymers__(long chains of repeating chemical units called monomers).
27. What are the two parts that make up the fabric? (smaller components)
a. _____filaments_____________________________________________
b. ____________fibers______________________________________
28. What is the warp and weft on a piece of fabric?
a. Warp-_continuous strands__________________________________________
b. Weft-_woven strands__________________________
29. How is synthetic fiber made? _______spinnerets turn chemicals (polymers) into strands________
30. What are some ways that you would go about identifying fibers? a. __microscope______,
b. __burn test__, c. __thermal decomposition _____,d. ____chemical test_____