1. Collecting Fingerprints
Target 2-3
Thursday,
October 26, 2017

2. Target 2-3
I can match fingerprints by collecting, classifying, and analyzing them.

3. Collecting Print Samples
Crime Scene
Suspects
Victim
Controls

4. Crime Scene Prints Visible Prints
Finger came in contact with a colored material such as blood, paint, ink
To collect: Take photos

6. Crime Scene Prints Plastic Prints
Physical impression (3-D) in a soft substance such as wax, clay, putty, soap, nail polish
To collect: Take photos

8. Crime Scene Prints Latent Prints
Invisible prints left when friction ridges transfer oils from skin to a surface
Collection technique depends on the surface

10. Dusting Apply a fine powdery dust to a surface Use for smooth surfaces
Dust will stick to oils from the print
Excess dust can be knocked loose or blown away
Use for smooth surfaces
Glass, plastic
Can be done at the scene

12. Cyanoacrylate Fuming
Expose the surface to cyanoacrylate vapor (superglue!)
Fumes will stick to oils from the print
Fumes will appear white when dried
Use for small, smooth objects
Glass, plastic
Must fit in a small chamber for fuming
Object must be transported to the lab
Fuming must be done in an enclosed chamber

14. Iodine Fuming Expose the surface to iodine vapor
Fumes will stick to oils from the print
Captured fumes will turn brown
Use for semi-porous surfaces
Skin, cardboard
Object must be taken to a lab
Fuming must be done in an enclosed chamber
Iodine is expensive and toxic

16. Ninhydrin Spray or soak surface in ninhydrin Use on porous objects
Ninhydrin will react chemically with proteins in skin oils
Chemical product turns purple when dry
Use on porous objects
Paper, fabric
Must be done in a lab
Sample must soak and dry for 24 hours

18. Silver Nitrate Spray surface with silver nitrate solution
Silver nitrate reacts with salt in skin oils
Chemical product appears black under UV light
Use for porous surfaces
Paper, walls, furniture
Can be done at the crime scene
Silver nitrate residue is toxic and must be cleaned up later