Forensics Unit 2 Notes
Chapter 4 – Fingerprints
I.
Historya. In 1924, the fingerprint records of the Bureau of Investigation and Leavenworth Prison merged
to form identification records at the FBI. This is the largest collection of fingerprints in the
world. (IAFIS)
II.
Classification of Fingerprints
a. Core- area found near the center of all loop and whorl patterns
Fingerprint Patterns
b. Arch patterns have lines that start at one side of the print and then move toward the center of the
print and leave on the other side of the print
c. Whorl patterns have a lot of circles that do not exit on either side of the print
d. Loop patterns have lines that start at one side of the print and then move toward the center of the
print and leave on the same side of the print they started on
i. Delta- (Triradius) a triangle shape found in all loop and whorl patterns
e. Henry Classification Systemi. Primary Classification-identifies the presence of whorl patterns and each finger is
assigned a number
ii. Secondary Classification-the frequency of each fingerprint pattern is used to calculate
probability
f. Ridge classification- use minutiae- the fine structure of ridge characteristics. (see powerpoint)
i. 150-200 minutiae in a properly rolled fingerprint
ii. 8-12 points of similarity are considered sufficient proof.
III.
Types of fingerprints left at crime scenes
a. Visible prints are fingerprints that one can see with the naked eye
b. Latent prints are fingerprints that are invisible
c. Plastic prints are fingerprints that leave an impression on objects such as soap or wax
d. Cheiloscopy- the study of lip prints
IV.
Methods used to obtain fingerprints
a. Ink pad or pencil smudge
b. Dusting
c. Impression- used for plastic prints
d. Fuming with super glue
e. Other methods used in special cases