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Types of Crime Scene Prints

Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

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Page 1: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Types of Crime Scene Prints

Page 2: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Types of Crime Scene Prints

• Three Types:Patent PrintsPlastic PrintsLatent (Invisible) Prints

Page 3: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Patent Prints• Can be seen with the

naked eye• Made by fingers

touching a surface after ridges have been in contact with a colored material such as blood, paint, grease, ink, etc.

Page 4: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Plastic Prints• Can be seen with the naked

eye• Made by ridge impressions left

on a soft material such as putty, wax, soap, dust, wet painted surfaces, etc.

Page 5: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Latent (Invisible) Prints

• Latent fingerprints are those that are not visible to the naked eye. These prints consist of the natural secretions of human skin and require development for them to become visible.

• They are made by impressions caused by transfer of body perspiration or oils present on finger ridges to the surface of an object

Page 6: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Detection of Prints• Latent prints must be

developed (found) through different methods

• The method used is dependent on the surface being examined

Page 7: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Surface Conditions

• Hard, nonabsorbent surfaces (glass, mirrors, tile, painted wood): Powders or Super Glue Fuming

• Absorbent surfaces (paper, cardboard, cloth): One or more specific chemicals

Page 8: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Fingerprint Powders• Non-absorbent surfaces only• Applied with a camel’s hair or

fiberglass brush (DO NOT TOUCH)• Color of powder chosen contrasts

with surface color• Powder adheres to oils and

perspiration left by ridges• Print can be lifted off the surface

and preserved

Page 9: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

How to Develop Fingerprints With Black

Powder

• http://www.youtube.com/watch?v=tqFzVfPRd5s

Page 10: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Fingerprint Powders

• Some investigators use fluorescent powder and UV lights to help them find latent prints on multi-colored or dark surfaces.

• Magnetic powder can also be used to reveal latent prints. This type of powder works better on shiny surfaces, some paper, or plastic baggies or containers.

Page 11: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Iodine Fuming

Oldest chemical method for developing

latent prints.

• Iodine is a solid crystal that, when heated, is transformed into a gas through sublimation

Page 12: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Iodine Fuming

• Iodine fumes react with oils and fats to produce a temporary yellow-brown colored print.

• Iodine prints are not permanent and must be photographed immediately or fixed with starch solution, which can last about 1 month

Page 13: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Ninhydrin• Chemical used to develop

prints on porous material by reacting with amino acids in perspiration

• Developed prints appear purple-blue in color

• Prints appear within an hour or two and fully developed in 24-48 hours

• Commonly used on paper products

Page 14: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Superglue Fuming• Used on nonporous surfaces such

as metal, electrical tape, leather, and plastic bags

• Active ingredient: cyanoacrylate ester

• Evidence is placed in a fuming chamber and the cyanoacrylate is heated and covers the object and produces a hard white latent print

Page 15: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Super Glue Fuming

• http://www.youtube.com/watch?v=FkcSkADVMIM

Page 16: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Laser Light• Perspiration contains a variety

of components that fluoresce when illuminated by laser light

• Because of the fluorescence, latent prints can be seen with the naked eye

• Almost never used anymore with the invention of alternate light source (ALS) latent print examination

Page 17: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Alternate Light Source (ALS)

• Works because perspiration fluoresces under different wavelengths of light

• Can adjust the wavelength of light to be aimed through a fiber optic cable

• More commercially available than laser light setups

Page 18: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Preservation of Prints• Common fingerprint methods do

not interfere with further DNA analysis

• However, when biological material remains, fingerprints should be developed at the crime lab instead of at a crime scene

Page 19: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Preservation of Prints• After prints have been found,

photos must be taken

• If object is small enough to be transported without destroying the print, it should be preserved intact

• Cellophane should cover the print to protect from damage

Page 20: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Preservation of Prints• Prints on immovable objects

should be lifted

• Lifted prints should be preserved on a card that provides contrast

Page 21: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Kendall/Hunt Publishing Company 21

Palm - friction ridges can be identified and may be used against suspects

Other Prints

Page 22: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Kendall/Hunt Publishing Company 22

Footprints are taken at birth as a means of identification of infants.

Other Prints

Page 23: Types of Crime Scene Prints. Three Types: Patent Prints Plastic Prints Latent (Invisible) Prints

Other PrintsIris Scan recognition is the process of recognizing a person by analyzing the random pattern of the iris. The automated method of iris recognition is relatively young, existing in patent since only 1994.