Impressions Evidence

Patent Latent Plastic

Can easily be seen 2D uses another substance to create the impression such as: blood, ink, etc.

Cannot be seen by the naked eye Anything that requires special forensic enhancement techniques 2D Can be created by the oils on your fingerprints, sweat, etc.

Easily seen Uses another SOFT surface to create an impression. 3D You can see the individual ridges in the print. You aren’t adding anything to create the surface, just things coming together.

They form in the wombs and each type of fingerprint (loop, whorl, arch) has a genetic factor that influences the type.

To grip things

arches loops whorls

plain tented

ulnar radial

plain central pocket double loop accidental whorl

a smooth hill, like a little wave.

A sharp peak, steep.

swings (circular part) towards the thumb bone, relative to the hand,

swings (circular part) towards the pinky bone, relative to the hand. Ulna - under

Minutiae are the individual fingerprint ridge characteristics. There are about 150 minutiae on a singular, complete fingerprint. (see slides)

Fork double fork (bifurcation) triple fork (bifurcation) delta dot bridge hook eye short ridge ending ridge

physically chemically alternate light sources

using dusting powders like black powder or magnetic powder. - Fine particles are brushed onto the suspected fingerprint and adhere to the residue to make it visible. - They are then listed using transparent lifting tape and the tape is mounted to an evidence card. Magnetic powders are becoming more popular because they are simply more easy to clean.

using an alternate light or laser illumination.

• Number of people present • pigeon toed, duck feet • type of footwear (could indicate profession) • Surface the show walked on (where they’ve been?!) • Shoe size • Left of right shoe • Wear pattern • How they are moving (walking, running) • Gate • Weight and size • Height

Photograph it with ruler Lift patent and latent cast plastic

Take photos before anyone touches the print Take pictures with and without a ruler for scale Take them from a 90 degree to reduce distortion multiple photographs should be taken from all angles Use indirect lighting to reduce glare This is mostly done for patent because it can be difficult to lift, but should be done for all kinds.

Luminol for bloody footprints Dusting and lifting Electrostatic lifting Gel lifting

Sand or soil impressions use plaster of Paris Hairspray is used to keep the print firm If it is snow, snow print wax must be used to not melt the print (dental snow). It hardens very fast and does not melt the print.