 Fingerprints are considered individualized evidence. Each person has their own unique fingerprints.  A fingerprint pattern will remain unchanged for the life of an individual; however, the print itself may change due to permanent scars and skin diseases.  Fingerprints have general characteristic ridge patterns that allow them to be systematically identified.

 Fingerprints is the oldest forensic science technology used successfully in the apprehension and conviction of criminals  Fingerprints have been used to identify individuals for thousands of years  New technology such as luminescence allows even greater precision and certainty of identification

 There are three types of fingerprint evidence that may be gathered from a crime scene: 1. Visible: easily seen by the human eye and left in blood, dirt, paint, etc. 2. Latent: not visible to the human eye and left due to perspiration or skin oils 3. Physical: impression left in soft material, such as wax, window caulking, or food items

 Fingerprints are identified based on the three basic features: 1. Loops (66%): lines that enter from one side of the print, curve and exit on the same side of the print (ulner, radial, double/twinned) Delta L – Radial Loop R - Ulnar Loop L – Ulnar Loop R - Radial Loop Radius Ulna Left Hand

 Fingerprints are identified based on the three basic features: 2. Arches (6%): lines enter on one side of the print and exit on the other (plain, tented) Plain Arch Ridges enter on one side and exit on the other side. Tented Arches Similar to the plain arch, but has a spike in the center. Spike or “tent”

 Fingerprints are identified based on the three basic features: 3. Whorls (34%): lines form concentric circles, whirlpools, or spirals (plain, central pocket, accidental) Draw a line between the two deltas in the plain and central pocket whorls. If some of the curved ridges touch the line, it is a plain whorl. If none of the center core touches the line, it is a central pocket whorl. Plain Whorl Central Pocket Whorl

Accidental Whorl Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories. Double Loop Whorl Double loop whorls are made up of any two loops combined into one print. Delta

Right Hand Left Hand Right Hand

 AFIS (Automated Fingerprint Identification System) has made fingerprint identification more useful to investigations.

 Latent prints can be made visible by enhancement using the following techniques:  Lifting Powder  Cyanoacrylate Fumigation  Iodine Fumigation

 Lifting powder: metal powders, such as aluminum, carbon, or tin, applied using a brush  Positively charged metal particles stick to negatively charged oil  After applying the powder, the print is lifted using clear tape  Works well on smooth, solid surfaces

 Cyanoacrylate (crazy glue) reacts with protein in the fingerprint to create a white residue  Works on dark, smooth, metallic objects

 Iodine reacts with sodium chloride (salt) in sweat to produce solid sodium iodide (dark brown)  Prints left on light colored and low density surfaces, such as paper, can be enhanced this way  Latent prints enhanced this way MUST be analyzed or photographed quickly since the print begins to degrade immediately 2NaCl (s) + I 2(g)  2NaI (s) + Cl 2(g)