1. Latent Fingerprint Recovery and Amplification
Unit Two
Forensic Science
Notes 2.4

2. In the human population: Whorls (27.9%) Loops (33.8%) Arches (38.3%)
Of the arches: 31.7% of human prints are plain arches; only 6.6% of prints are tented arches

3. Fingerprint Types
Fingerprints found at a crime scene fall into three categories
Patent
Plastic
Latent

4. Patent Fingerprints
Patent fingerprints are those that are readily seen and are transferred from the friction ridges by a foreign substance, like blood, oil, paint or dirt.

5. Plastic Fingerprints
Plastic fingerprints are prints that are impressed into a soft substance such as wet paint, putty or wax.

6. Latent Fingerprints
The latent fingerprints are those left behind by the natural body secretions, such as perspirations, or oils and acids. They are not readily visible.

7. Fingerprint Recovery
There are many techniques and methods in recovering fingerprints such as the use of different powders, light sources, sprays and photographic filters

8. Fingerprint Powders
Various dusting powders can be used depending on the type of surface to be examined
carbon black powder on light surfaces
lanconide for prints on dark surfaces
aluminum powder can be used on either type
Remove the excess powder by blowing the dust from the surface or by gently brushing it away.
If a camera is available, try to photograph the print.
Lift the print from the surface with tape

9. Fingerprint Amplification
There are many techniques and methods in recovering fingerprints such as the use of different chemical agents: ninhydrin, cyanoacrylate, and iodine fuming.

10. Konai's hand print was impressed on the back of the contract. , .
Ninhydrin
Konai's hand print was impressed on the back of the contract. , .
Ninhydrin bonds to the amino acids in the fingerprint.
used on porous and non-porous surfaces
purple-colored prints
permanent
The Acetone that carries the ninhydrin is harmful to the respiratory system (so don’t inhale!)

11. Iodine
Solid iodine crystals give off vapors that bond physically to the oily substances of a fingerprint.
used on porous and non-porous surfaces
brown-colored prints
not permanent unless fixed
works best on fresh prints
Iodine fumes are toxic and also strongly corrosive.

12. Cyanoacrylate Cyanoacrylate interacts with a latent fingerprint.
Super Glue is 98 to 99 percent cyanoacrylate ester
The fumes and the suspect material are placed in an enclosed chamber for up to 6 hours.
can be mixed with sodium hydroxide
can be heated gently
The cyanoacrylate bonds to
the prints leaving a white
residue