forensic fingerprints

fingerprints are ________ evidence. no 2 people have the same prints

individual

purpose of friction ridges

increase grip & sense of touch

another term for friction ridges

fingerprints

latent fingerprints

invisible prints left behind on surfaces by sweat, oil, other natural secretions

patent (visible) fingerprints

visible prints made by touching blood, paint, ink, or grease

plastic fingerprints

ridge impressions left on soft materials like putty, wax, soap, dust

difference between ulnar loop and radial loop

ulnar opens towards the little finger

radial opens towards the thumb

when are a person's fingerprints formed?

10th week of gestation (pregnancy)

what 2 things influence the formation of fingerprints?

genetics

environmental factors

how can fingerprints be altered

injury or damage; scarring or burns; intentional damage; surgery

are fingerprints of identical twins the same

no, each person's fingerprints are unique (different)

Can the patterns of an individual's prints change during his lifetime?

No, fingerprint patterns remain the same throughout a person's life unless altered by significant injuries, scarring, or certain medical conditions.

Why do children's prints not last as long as adult prints?

Children's fingerprints do not last as long because their skin produces less oil and sweat, making the prints fainter and more likely to fade quickly.

What is IAFIS?

integrated automated fingerprint identification system;

a database that stores & matches fingerprints

what else is kept on IAFIS to help identify people

criminal history records, mugshots, scars, tattoos, palm prints, others

methods used to reveal latent prints.

Ninhydrin:

Reacts with amino acids in sweat to produce a purple print.

methods used to reveal latent prints.

dusting:

Applying powder to make prints visible.

methods used to reveal latent prints.

Super glue fuming:

Using cyanoacrylate vapor to make prints adhere to surfaces

methods used to reveal latent prints.

Silver nitrate:

Reacts with salts in sweat and develops under UV light.

How do lasers reveal fingerprints?

Lasers can make fingerprints visible by causing the natural glow in sweat or by reacting with fingerprint powders or chemicals that light up under laser beams.

How does super glue fuming work? What chemical is used to see the prints?

Super glue fuming uses vapors from a chemical called cyanoacrylate. These vapors stick to fingerprint residues, making the prints show up as white on non-porous surfaces.

What type of powder is used with ultraviolet light?

Fluorescent powders are used under UV light to make fingerprints glow, so they are easier to see.

How would an investigator dust for prints on a dark surface?

The investigator would use light-colored powders, like white, silver, or fluorescent powder, to make the prints stand out against the dark background.

What factors decide the method used to find latent prints?

Things like the type of surface (porous or non-porous), how old the print is, the environment, and what forensic tools are available can all affect the method used.

How is fingerprinting changing with new technology?

New technology includes:

Better AFIS (automated fingerprint databases) for faster matching;

Live scan technology for taking fingerprints digitally;

3D fingerprint scanning for more accurate results;

New chemicals to reveal older or damaged fingerprints.

What is an individual's ratio in the Primary Classification System if they have no whorls?

no whorls = 1/1. always add 1/1 after calculating whorls

arch print

made up of ridges lying one above another

arch prints have a ___% occurrence

5

whorl print

made up of one or more free recurving ridges & 2 points of delta (triangle)

whorl print has a ___% occurrence

30

loop print

made up of one or more ridges entering from one side of the print, curving and exiting from the same side

loop print has a ___% occurrence

65

label the characteristics on the print

red is?

hint: 2 ridges intersect

crossover

label the characteristics on the print

orange is?

hint: center of pattern

core

label the characteristics on the print

yellow is?

hint: ridge splits into 2 (bi = 2)

bifurcation

label the characteristics on the print green is?

hint: ridge that stops

ridge ending

label the characteristics on the print

sky blue is?

hint: on its little ___, not attached to others

island

label the characteristics on the print

blue is?

hint: triangle

delta

label the characteristics on the print

purple is?

pore