Methods for Taking Fingerprints
Review: https://learninglab.si.edu/resources/view/196612 Intro: https://learninglab.si.edu/resources/view/633923
Visible Prints Visible prints are made when fingers touch a surface after touching 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.
Latent Prints On hard and non-absorbent surfaces On Porous surfaces Ex. tile, mirrors, painted wood Developed with powder On Porous surfaces Ex. Papers cardboard, and cloth Devolved using chemicals
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 https://learninglab.si.edu/resources/view/643343
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
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
Transporting prints Small Objects Large 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
Classifying prints
Pattern Prevalence
What Your Whorls could mean https://learninglab.si.edu/resources/view/2839359
One more identification technique Loop Count