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Fingerprints day 2: Ridge Classification and Lifting Prints. September 10, 2014. Ridge Classification – Example 1. Use your sheet to determine what characteristics you see. Add pore to your sheet – how would you describe it?. Ridge Classification – Example 1. - PowerPoint PPT Presentation
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September 10, 2014
FINGERPRINTS DAY 2:RIDGE CLASSIFICATION AND LIFTING PRINTS
RIDGE CLASSIFICATION – EXAMPLE 1
Use your sheet to determine what characteristics you see.
Add pore to your sheet – how would you describe it?
RIDGE CLASSIFICATION – EXAMPLE 1
A core is the center of a loop or whorl.
Crossover is another name for a bridge.
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#1 is ...
1. Trifurcation2. Bifurcation3. Spur4. delta
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#1 is ...
1. Trifurcation2. Bifurcation3. Spur4. delta
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#2 is ...
1. delta2. spur3. island4. ridge ending
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#2 is ...
1. delta2. spur3. island4. ridge ending
RIDGE CLASSIFICATION – EXAMPLE 2
4
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1
Show the correct characteristic with your fingers.
#3 is ...
1. bridge2. core3. island4. eye
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#3 is ...
1. bridge2. core3. island4. eye
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#4 is ...
1. bridge2. core3. island4. eye
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
#4 is ...
1. bridge2. core3. island4. eye
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
# 5 is ...
1. bridge2. bifurcation3. ridge ending4. spur
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
# 5 is ...
1. bridge2. bifurcation3. ridge ending4. spur
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
# 6 is ...
1. bridge2. bifurcation3. ridge ending4. spur
RIDGE CLASSIFICATION – EXAMPLE 2
4
23
6
5
1
Show the correct characteristic with your fingers.
# 6 is ...
1. bridge2. bifurcation3. ridge ending4. spur
TYPES OF FINGER PRINTS
• Visible prints - prints that can be seen by the naked eye, made if the finger has touched grease, blood, paint, etc.
TYPES OF FINGER PRINTS
• Visible prints - prints that can be seen by the naked eye, made if the finger has touched grease, blood, paint, etc.
• Latent prints – prints that are invisible to the naked eye; formed from natural body oil and perspiration
TYPES OF FINGER PRINTS
• Visible prints - prints that can be seen by the naked eye, made if the finger has touched grease, blood, paint, etc.
• Latent prints – prints that are invisible to the naked eye; formed from natural body oil and perspiration
• Plastic prints – 3D negative impression of a fingerprint, made by pressing a finger into a soft, moldable material, such as putty, wax, glue, candy, etc.
COLLECTING FINGERPRINTS FOR EVIDENCE
• Visible and plastic prints can often just be photographed for evidence.
• Latent prints must be made visible to be observed & collected.
VISUALIZING LATENT PRINTSThere are three basic methods for visualizing latent prints
1) Oblique lighting
• Most prints (even so-called latent prints) are at least partially visible and can be found by shining a flashlight or alternate light source along surfaces at an angle.
• Used to find prints, especially over large areas
• UV lights and lasers make fingerprints fluoresce, and will reveal more prints than regular flashlights.
VISUALIZING LATENT PRINTSThere are three basic methods for visualizing latent prints
1) Oblique lighting
• Most prints (even so-called latent prints) are at least partially visible and can be found by shining a flashlight or alternate light source along surfaces at an angle.
• Used to find prints, especially over large areas
• UV lights and lasers make fingerprints fluoresce, and will reveal more prints than regular flashlights.
After finding prints with oblique lighting, the prints will need to be further developed (by the methods described next) so that a permanent record can be made)
VISUALIZING LATENT PRINTS2. Powder Dusting
• Can be used to locate (over small areas), enhance, and preserve prints
• Powder is lightly dusted onto a surface so as not to smear the prints.
• The powder is lifted with clear tape and put onto backing paper.
• Powders come in a variety of colors, and some are magnetic.
VISUALIZING LATENT PRINTS3. Chemical Processing
More effective than dusting on porous surfaces, such as paper, leather, styrofoam, etc.
3 chemical methods you need to know:
• Ninhydrin
• Iodine
• superglue
LATENT PRINTS – CHEMICAL PROCESSING
1) Ninhydrin processing • Used on porous surfaces, including paper• Object is dipped in or sprayed with ninhydrin solution• Reacts with amino acids in print• Turns purple
2) Iodine processing• Used on valuable objects because it is impermanent• Evidence is placed in fuming chamber with crystal iodine• Iodine is trapped in oils of print to produce brown color• Will fade over time
LATENT PRINTS – CHEMICAL PROCESSING
3) Superglue (cyanoacrylate ester)
• Evidence is placed in a fuming chamber with superglue
• Heat accelerates the process
• The glue bonds to the print, forming a strong, stable, off-white impression.
• Superglued prints are usually further treated with chemicals or powders to enhance the visibility of the print.
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
3. What would be the best way to search for prints on a document?
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
3. What would be the best way to search for prints on a document?
Ninhydrin spray
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
3. What would be the best way to search for prints on a document?
Ninhydrin spray
4. What is the main benefit of iodine staining?
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
3. What would be the best way to search for prints on a document?
Ninhydrin spray
4. What is the main benefit of iodine staining?
It doesn’t last – good for valuable items
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
3. What would be the best way to search for prints on a document?
Ninhydrin spray
4. What is the main benefit of iodine staining?
It doesn’t last – good for valuable items
5. What is a major benefit of superglue fuming?
QUICK REVIEW
1. What would be the best way to look for latent prints over a large area?
Oblique lighting, especially with alternate light source
2. What would be the best way to search for prints on a gun?
Dusting and/or superglue fuming
3. What would be the best way to search for prints on a document?
Ninhydrin spray
4. What is the main benefit of iodine staining?
It doesn’t last – good for valuable items
5. What is a major benefit of superglue fuming?
It creates durable impressions
