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FORENSIC SCIENCE Prints. Prints. Making Prints Rolling prints Modus Operandi--primary identification number Lifting Prints Black, white and fluorescent powder Chemicals--ninhydrin, iodine, silver nitrate, cyanoacrylate Other Types of Prints
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Prints • Making Prints • Rolling prints • Modus Operandi--primary identification number • Lifting Prints • Black, white and fluorescent powder • Chemicals--ninhydrin, iodine, silver nitrate, cyanoacrylate • Other Types of Prints • Palm, lip, teeth, eye, ear, voice, shoe and feet prints
Fundamental Principlesof Fingerprints • A fingerprint is an individual characteristic. • A fingerprint will remain unchanged during an individual’s lifetime. • Fingerprints have general characteristics ridge patterns that permit them to be systematically classified.
Ridge Characteristics Minutia--lines of the fingerprint • ridge ending • bifurcation • short ridge • dot or fragment • island • enclosure
MINUTIA RIDGE ENDING BIFURCATION
MINUTIA SHORT RIDGE DOT or FRAGMENT ISLAND ENCLOSURE
Arch An arch has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores. Types • Plain • Tented
Loop A loop must have one or more ridges entering and exiting from the same side it began. Loops must have one delta. Types • Radial--opens toward the thumb • Ulnar--opens toward the “pinky” (little finger) Which type of loop is this, if on the right hand? Left hand?
Whorl A plain or central pocket whorl have at least one ridge that makes a complete circuit. A double loop is made of two loops and an accidental is not covered by other categories. Types • Plain • Central Pocket • Double Loop • Accidental
Primary Identification Numbers Fingers are numbers 1 through 10 starting with the thumb on the right hand and continuing through with the thumb on left hand. Each finger is then given a point value as seen in the chart below. 1. right 2. right 3. right 4. right 5. right thumb index middle ring little 16 16 8 8 4 6. left 7. left 8. left 9. left 10. left thumb index middle ring little 4 2 2 1 1
Primary Identification (cont) Set up a ratio of even numbered fingers over odd numbered, adding one in both the numerator and denominator. 2. right 4. right 6. left 8. left 10. left index ring thumb ring little 16 8 4 2 1 1 1 + 16 8 4 2 1 1. right 3. right 5. right 7. left 9. left thumb middle little index little
Fingers 2 8 2 1 16 8 4 1 16 4
Latent Prints Latent fingerprints are those that are “hidden” and are not visible to the naked eye. These prints consist only of the natural secretions of human skin and require treatment to cause them to become visible. Most secretions come from three glands: • Eccrine--largely water with both inorganic and organic contaminants (salts) • Apocrine--secrete cytoplasm and nuclear materials • Sebaceous --secrete fatty or greasy substances.
Lifting Latent Prints Developing a print requires chemicals that react with secretions that cause the print to stand out against its background. It may be necessary to attempt more than one technique, done in a particular order so as not to destroy the print. • Powders--adhere to both water and fatty deposits. Choose a color to contrast the background. • Iodine--fumes react with oils and fats to produce a temporary yellow brown reaction.
Lifting Latent Prints (cont) • Ninhydrin--reacts with amino acids to produce a purple reaction. • Silver nitrate--react with chlorides to form silver chloride, a material which turns gray when exposed to light. • Cyanoacrylate--”super glue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit. • In modern labs and criminal investigations, lasers and alternative light sources are used to view latent fingerprints. It was first used by the FBI in 1978. Since lasers can damage the retina of the eye, special precautions must be taken and a filter used.
Other Prints • Ears--shape, length and width • Face--pictures being used in Florida to find criminals • Voice--electronic pulses measured on a spectrograph • Feet--size of foot and toes; lines of the feet • Shoes--can be compared and identified by type of shoe, brand, size and year of purchase
Other Prints Palm--lines can be identified and may be used against suspects.
Other Prints Foot Prints are taken at birth as a means of identification for infants.
Other Prints Lips--display one of five common patterns • Short vertical lines • Long vertical lines • Rectangular lines that may crisscross • Diamond • Branching
Other Prints Teeth--bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.
Other Prints The blood vessel patterns may be unique to individuals. They are used for today various security purposes.
“FINGERED”Crazy Criminals A New Jersey resident phoned police after finding her back door slightly ajar with a muddy palm print on the glass. When the officer questioned the woman, it was determined that she had been gardening. When he compared her hand with the lifted print, he had a match!!
PORTFOLIO A portfolio is a collection of work that demonstrates what you know and can do. It shows your best work. In this unit, you will put together a portfolio of your work on making and lifting various prints. You will add to your portfolio as you work through the labs in class and put it in to a final form at home. You will be given both written instructions and an assessment list.
