Forensic Fingerprint, Biometrics, and Ballistics Techniques

common ridge characteristic

includes minutiae such as bifurcations, ridge

endings, islands, etc

three major fingerprint pattern

loop, whorl and arch

What is the most common method used to develop prints?

Dusting

How can dusted prints be lifted?

With tape

What is ninhydrin used for in print development?

It changes color due to the amino acids present.

What does cyanoacrylate fuming do in print development?

It polymerizes on the print residue to leave a permanent white impression.

What type of powders are often used in print development?

Fluorescent powders

two main functions of biometrics

Biometric matching or verification and Biometric

identification

physiological biometrics

Fingerprints, hand, iris, retina, and facial scans

Which is most cost effective? Most secure? Least accurate?

Fingerprint is most cost effective, retina/ iris scanning is most secure, least acurate is facial recognition

How are iris details captured and characterized

Iris biometrics is replacing retina biometrics because it is an all around better technology and more functional for both law enforcement and business security.

behavorial biometrics examples

Handwriting, voice, keystroke, and gait recognition

three steps involved in biometric system

Enrollment process, Feature extraction, and

Template generation

Interstate Photo System

serves as the FBI's biometric identity and criminal history records system and maintains the fingerprints and associated identity information of individuals submitted to the FBI for authorized criminal justice, national security, and civil purposes.

parts of the compound microscope

base, arm, stage, body tube, coarse

adjustment, fine adjustment, illuminator, condenser, objective lens, and eyepiece lens

Comparison microscope

used to compare hair or fibers and examine rifling marks on bullets

Stereomicroscopes

used to locate trace evidence in debris, garments, weapons, or tools

the polarizing microscope is designed to characterize

plane-polarized light

Polarizing microscopes

used to characterize minerals present in soil or birefringent synthetic fibers.

Scanning Electron Microscopes

used to analyze pollen, spores, fibers, and gun powder residue

Anemophilous pollen dispersion

Pollen dispersion through wind

Entomophilous pollen dispersion

Pollen dispersion through insects

techniques for rifling a barrel

roach cutting, button process and mandrel rifling

Class bullet characteristics of bullet and cartridge casings

number of lands and grooves, direction of twist and degree of rotation

individual characteristics of bullet and cartridge casings

striation markings

Lands and grooves

Spiral cuts inside a gun barrel that leave unique impressions on a bullet, allowing firearm identification.

Striation markings

Fine lines on the surface of a bullet created by the irregularities inside the barrel; used for bullet comparison.

Firing pin impression

The mark left on a cartridge case when struck by the gun's firing pin.

Breechblock impression

The pattern left on the base of a cartridge case when it's forced back against the breechblock during firing.

NIBIN

National Integrated Ballistic Information Network; a database that stores images of markings on bullets and cartridge cases to link crimes involving the same firearm.

Gunshot residue (GSR) distance determination

The process of determining how far a weapon was fired from a target by comparing powder residue patterns on clothing or skin to test shots at varying distances.

Powder-residue pattern test

Test shots are fired at different distances using the suspect weapon to compare residue patterns with those on the victim.

Close-range gunshot characteristics

May show powder tattooing, burns, or soot deposits around the bullet hole.

Distant gunshot characteristics

Shows a clean bullet hole with no visible powder residue around it.

Greiss test

Detects nitrite residues from gunpowder to indicate a person fired or was near a fired gun.

Wallner lines

Stress marks on glass fractures used to determine the direction of force.