I made this to show ridge characteristics to my students

1. Fingerprints

2. Fingerprint origin
• During the third or fourth month of fetal
development the sweat glands form in the
skin through small pores. Pores link
together to form a series of ridges that are
unique to every individual.

3. How are fingerprints made?
• Materials are continually secreted from the
pores in the skin within the ridges of the
fingers.
• 98-99% of the secreted material is water
and the other 1-2% is other organic and
inorganic materials.

4. • Any sebaceous oils on the fingers is
transferred from other areas of the body
and is collected in the ridges.
• Other objects that have an oily or greasy
residue also transfer materials to the
fingers when touched.

5. • All of the materials that gather in the
ridges can be transferred from the finger
to the touched object…leaving behind a
distinct fingerprint

6. Types of prints
• There are three types of prints that can be
found at the scene of a crime.
– Latent
– Patent
– Plastic

7. Latent prints
• Latent prints are considered to be any
print that is not easily seen.
• They require Processing with the use of
powder and/or chemicals like super glue
fuming

8. Patent prints
• Patent prints are any print that can be
easily seen because they were made with
a substance on the fingers…such as
blood, oil, or ink.
• Patent prints need to be photographed
and then collected using lifting tape…they
do not require chemicals

9. Plastic prints
• Plastic prints are three-dimensional
impressions made in a substance that
holds the shape of the ridges on the
fingers such as putty, clay, or wax
• Plastic prints should be photographed first
and foremost and then attempts can be
made to get an impression using plaster
or other casting materials

10. Analyzing prints
• In the past fingerprints were analyzed by
fingerprint analyzers and then they would
be compared to fingerprints on file.
• Now, computers do the work by digitally
scanning prints into a large database
called the Automated Fingerprint
Identification System (AFIS).

11. • The computer uses an automated
scanning device to convert the image of a
fingerprint into digital ridge characteristics

12. What is analyzed?
• Ending ridge
• Fork (bifurcation)
• Island ridge
• Dot
• Bridge
• Spur
• Eye
• Double bifurcation
• Trifurcation

13. Ridge ending

14. Fork/Bifurcation

15. Island ridge

16. Dot

17. Delta & Bridge

18. Spur

19. Double bifurcation

20. Eye

21. Trifurcation