FingerPrinting I Flashcards
Compound was called Triketihyrindene Hydrate and react to alpha amino acids, valuable for detection of the non-biuret dialyzable amino acids, various tissues, milk,urine, saliva, blood, plasma, serum, fresh eggs, fresh & boiled meats, sweat
Ninhydrine
Discovered by S Ruhemann in 1910
Ninhydrin
1954 recognized as a latent print reagent on porous surfaces, originally highly flammable because of solvent, 1974 trifluortrichlorethane made it nonflammable and does not dissolve ink, 1194 fluorisol is banned, replaced by Genesolv 2000, heptane, and recently HFE7100
Ninhydrine
what is the proper sequencing when processing Ninhydrine and a porous surface?
Visual examination, luminescent treatment, Iodine Fuming, DFO, Ninhydrine, Physical Developer
What is the application process for Ninhydrine?
Apply by dipping, spraying, or brushing. Development of chemical reaction naturally can take several weeks, heat & humidity can speed the process, sensitivity may not be high, developed prints are not permanent
1990 Grigg Pounds modified the Ninhydrine molecule, reacts with alpha amino acids on paper, seen in both color and fluorescence, has red pigment closely resembles Ruhemann’s purple
1,8-Diazafluorene-9-one (DFO)
At what stage is DFO used?
1st stage of the chemical sequence for paper & porous substrates
Characteristics of DFO
more sensitive than Ninhydrine in developing prints, apply by submersion or spraying for 5 sec. air dry, re-apply, air dry, heat w/ no humidity at 100 C, view under light source at 470nm-570nm
A photographic process based on the formation of silver onto a latent print
Physical Developer
Primary ingredients: Ferric Nitrate & Ferrous Ammonium Sulfate coupled with a metal salt mixture
Physical Developer
Reacts to the lipid material in sebaceous secretions triglycerides, wax ester, squalene, etc. When applied it forms a gray silver deposit
Physical Developer
If paper is or known to have been wet it should be used solely & not in conjunction with DFO and Ninhydrine, sensitive to water insoluble constituents
Physical Developer
Can develop prints on paper, non porous surfaces (w/ special method) pressure sensitive tapes. Also can be used on stamps, money, emulsion side of photographs, & envelope closure flaps
Physical Developer
Normally requires a 3 step process. water & acid pretreatment, silver physical developer, water & hypochlorite post treatment. On non porous surfaces it requires a multi metal deposition (vacuum metal deposition) process using colloidal gold & zinc otherwise prints may not visualize, caution-background can overdevelop
Physical Developer
A silver based process that reacts w/ the chlorides in Eccrine deposits on porous surfaces
Silver Nitrate
How to process Silver Nitrate
Immersion, allow to dry, then expose to high intensity lamp until prints develop. Remove from light immediately or overdevelopment of the background may ruin the print, place in stabilizing rinse.
This method has primarily been replaced by a Ninhydrine/Physical Developer combination
Silver Nitrate
Developed in 1978 by Criminal Identification Division of the Japanese National Police, in 1982 introduced to the US by Ed German of the US Army Criminal Investigation Command and by the Bureau of Alcohol, Tobacco and Firearms
Cyanoacrylate Fuming
Chemical is alkyl-2-cyanoacrylate ester, aka super glue
Cyanoacrylate Fuming