Methods for Taking Fingerprints

1. Methods for Taking Fingerprints

2. Visible Prints • Visible prints are made when fingers touch a surface after toughing a colored substance like blood, ink, grease, paint, ect. • Plastic Prints • Are made when ridge impressions are left in soft surfaces like putty, wax, soap, dust, ect.

3. Latent Prints • On hard and non-absorbent surfaces • Ex. tile, mirrors, painted wood • Developed with powder • On Porous surfaces • Ex. Papers cardboard, and cloth • Devolved using chemicals

4. Latent print developing techniques • RUVIS • Reflected Ultraviolet Imaging System • Used to locate latent prints • Powder • Used once prints are located • Comes in several colors, magnetic and non magnetic • Adheres to perspiration and oils in print • Can be photographed or collected with tape

5. Latent print developing techniques • Super Glue fuming • Used on nonporous surfaces • Ex metals, electrical tape, leather and plastic • Fumes of super glue adhere to proteins in print and make a white visible print • Made of 99% cyanoacrylate ester, which is what makes the prints visible • Can be done in a fuming chamber or with a handheld wand • Iodine Fuming • Iodine crystals are heated and fumes combine with print to make them visible • Not permanent, will fade quickly

6. Latent print developing technique • Ninhydrin • Reacts with amino acids in prints to make a purple blue color • Physical Developer • Is a silver nitrate based reagent • Used when other techniques fail • Other chemicals used include those that cause the print to fluoresce under a laser or high intensity light source such as… • Quartz halogen, xenon arc, indium arc

7. Transporting prints • Small Objects • Transport entire object • Large objects • Photograph first • Allows print to be compared to digital database • Then lift with tape and place on labeled cards

8. Classifying prints

9. Pattern Prevalence

10. One more identification technique Loop Count Loop Count = 8

11. Bertillon Measurements

12. Why don’t we use it anymore?