Arch- classified by ridge lines that enter a print from one side and flow out the other side. About 5% of population has arches.
Ulnar loop opens toward the little finger. Radial loop opens towards the thumb.
Type lines- the pattern area of the loop surrounded by two diverging ridges
Delta-the ridge point nearest the type line at the point of divergence (inside triangular area of type line)
METHODS OF DETECTION
3 kinds of fingerprints
Visible- made by fingers that have touched a colored material- paint, blood, grease, ink
Plastic- prints left in a soft material. Wax, putty, soap, dust
Latent- “invisible” prints left by body perspiration or oils present on fingertips
Dust with camel hair brush using fingerprint powder. Make sure the color of the powder contrasts the surface to be dusted. Use black powder on light surfaces and grey on dark surfaces.
After photographing dusted prints they are “lifted” using tape and transferred to an index card.
Iodine fuming- method used to visualize prints using iodine crystals and heat. Good for prints on paper. This method must be photographed quickly because when the fuming has stopped the color fades.
Ninhydrin- forms a purple blue color with amino acids that are present in perspiration . This method has been effective visualizing prints on paper that are over 15 years old.
Cyanoacrylate fuming- (Super-glue) This method causes a white layer of super glue to coat latent prints making them more durable for lifting. This process takes 2-6 hours and a small heat source.
AFIS- Automated Fingerprint Identification System uses an automatic scanning device to compare suspect prints with a database of convicted criminals. Search a set of 10 fingerprints against 500,000 in .8 sec. The computer shows the most likely matches and a trained fingerprint expert makes the final comparison.
Drugs and physiological effects
Narcotics- pain killing substance that depresses vital body functions .
(Morphine, heroin, methadone, codeine)
Hallucinogens- drugs that cause marked alterations in thought processes, perceptions, and moods. (marijuana, lysergic acid diethylamide(LSD), PCP, MDMA or ectasy)