Fingerprints Lessons

•Fingerprints offer an infallible means of personal identification.

•Current Theory: no two people have the same fingerprint.

•This theory makes fingerprints an important ally of the forensics community.

Multiple Choice

If no two people have the same fingerprints, then select true or false for the following statement: identical twins have the same fingerprints.

• True

• False

•The origin of fingerprint identification is unclear.
•Archaeologists discovered fingerprints pressed into
clay tablet contracts dating back to 1792 BC.
•The world of fingerprinting has evolved from this date. Today, we use fingerprinting to match evidence to suspects.

Multiple Choice

Evidence suggests that fingerprint identification may have originated in ancient times. How has its purpose evolved to the present day?

• Fingerprint identification is primarily used for artistic purposes.
• Fingerprint identification has remained unchanged since ancient times.
• Fingerprint identification has evolved to modern forensic practices (match suspects).

• Fingerprint identification is solely used for security access control.

•Take a look at the surface of your fingerprints. What do you see?

•We all have ridges on our fingertips that help us grasp/hold objects.

•When we press these ridges against things, they leave a mark, an impression called a fingerprint.

Multiple Choice

On our fingerprints, we have _______ that allow us to grasp/hold objects.

• Fingerprint patterns

• Skin layers

• Nail beds

• Ridges

•The imprint of a fingerprint consists of natural
secretions of the sweat glands that are present in the ridge of the skin.

•When we touch objects, these secretions leave behind traces making a unique pattern of your dermal ridges.

Multiple Choice

How do sweat gland secretions contribute to the formation of a fingerprint when a person touches an object? (If you need a hint: they leave behind...?)

• Fingerprints are formed solely by skin oils, not sweat.
• Sweat gland secretions leave behind a trace that forms a fingerprint pattern.

• Sweat gland secretions evaporate immediately upon contact.
• Touching an object does not leave any marks or residues.

•Fingerprints are named for their patterns

• Loops
• Whorls
• Arches

Arches

(5% of population)

Whorls

(30% of population)

Loops

(65% of population)

Multiple Choice

Which is the most common fingerprint pattern?

• Loops

• Arches

• Whorls

• Many different patterns appear on fingerprints...

•Core: the center of a loop or whorl
•Delta: a triangular region near a loop

Ridge count

•Counting from the
core to the edge
of the delta

•Distinguishes one
fingerprint from
another

Multiple Choice

What is a ridge count and why is it important?

• A ridge count is the number of ridge units in a fingerprint from the core to the edge of the delta, important for fingerprint identification.

• A ridge count is the color of a fingerprint, important for aesthetic purposes.
• A ridge count is the age of a fingerprint, important for historical analysis.
• A ridge count is the depth of a fingerprint, important for security measures.

Types of Whorls

Types of Archs