Forensics: Fingerprinting

Finger printing has been a vital source of identifying for many centuries. A finger print is the pattern of someone's finger tip. The use of fingerprinting is very well known and used because no two people contain the same pattern, and the odds of that happening are very high.

History:

-In Ancient Babylon,  finger prints were collected when completing business transactions on clay tablets.
-14th Century Persia: Discovery, that no two fingerprints are identical.
-1823: John Evangelist Purkinje published a thesis about 9 fingerprint patterns, but also made no mention of fingerprints value in identifying people.
-1858: Sir William James Herschel begins to use fingerprinting on native contracts.

-1882: Sir Francis Galton, compiled a database of 8,000 fingerprints for further research into identification. Galton published Fingerprints, which was the first system for observing Fingerprints.

-AFIS (Automated Fingerprint Identification Systems): A database that automatically connects an unknown print to another known print. This system has since been used to identify many suspects.

Types of Prints

a. Latent : Partial prints left by the skin. May be smudged, distorted, or overlapped. Contain less clarity when observing because of the difficulty of reading.

b. Plastic : A print that when lifted contains the shape. Common examples are wax and putty.

c. Patent: A print of which is visible to the human eye. Some of the more obvious examples of a patent print are wet clay or possibly flour. Because of the visible nature the print can be photographed instead of lifted. Can be left on surface from ink, dirt or blood.

c. Direct/Exemplar: Known prints collected from a subject, such as when you apply for a passport.

Techniques/Chemicals used to develop prints on nonabsorbent, porous, hard, and smooth surfaces.
a. Black Powder(Charcoal or Carbon) is applied to light surfaces when lifting prints.
b. Gray Powder( Aluminum dust) is applied to dark surfaces.
c. Iodine is applied to surfaces, when heated the vapors will make the prints visible.
d. Silver Nitrate is used when lifting latent prints.

Basic Shapes/Patterns of Fingers
a. The Arch: made up of ridges lying above each other in an arch formation.
b. The Tented Arch: One upthrusting ridge that bisects the other ridges at basically right angles.
c. The Loop (Ulnar or Radial): Contains one or more recurving (free) ridges and one delta.
i. Ulnar: ridges flow from the side of the little finger.
ii..Radial: ridges flow from the side of the little finger.
d. The Whorl: Spiral formation.
e. The Twinned Loop: Two loop formations, separate and apart. Two Delta Points.
f. The Central Pocket Loop: Two delta points and consists of one or more free recurving ridges.
g. The Accidental: Two points of delta. One related to a recurve, the other related to a upthrust.








Procedure for collecting/lifting fingerprints:
Solid Dark Colored Surface:
1: Find a good print.
2: Use a white powder, such as talc, and gently cover the entire fingerprint with it.
3: Lightly blow off the excess powder. There should now be a visible print.
4: Using a clear piece of tape, cover the entire area to transfer the print off of the surface.
5: In this case, you can place the strip of tape onto a black sheet of paper. The print should now be easily visible and ready for the identification process.



Solid Light Colored Surfaces (Including Glass):
1: Find a good print.
2: Use a dark powder, such as graphite, and gently cover the entire fingerprint with it.
3: Lightly blow off the excess powder. There should now be a visible print.
4: Using a clear piece of tape, cover the entire area to transfer the print off of the surface.
5: In this case, you can place the strip of tape onto a white sheet of paper. The print should now be easily visible and ready for the identification process.


Lab: 
We began our lesson on fingerprints when we stamped our prints using an ink pad. 

In class we were supposed to be able to lift our prints from various surfaces. 
For example we had to collect our prints from a dark surface using a light powder. 

My fingerprint

If you look you will see that the fingerprint I lifted was my right thumb. 

The Second part of the lab we completed was lifting our prints from a light surface using a dark powder such as graphite. 

The middle print of all three collected was my left thumb. Can you see the connection?

Overall this project was very difficult because of the difficulty lifting the prints.