Forensic Science – Firearms Question and answers already solved 2023

Forensic Science – Firearms Question and answers already solved 2023Science systematic gathering of knowledge steps of scientific method 1. identify problem 2. develop hypothesis through research 3. test hypothesis with experimentation 4. form theory based on results 5. use theories to predict events 2 propositions of science of firearms 1. toolmarks imparted to objects by different tools will rarely lead a qualified examiner to conclude objects were marked by the same tool 2. most manufacturing processes involve transfer of rapidly changing or random marks onto WORKPIECES Tool definition harder of 2 objects comes into forceful contact with one another, softer object gets marked toolmarks; 2 types features imparted on object by contact + force exerted from tool 1. impressed toolmarks 2. striated toolmarks Impressed toolmark Features produced when tool contacts object w/enough force that it leaves an impression Striated toolmark (e.g...) features made when tool contacts object with lateral force + motion (pliers presses firmly into another piece of metal) 2 types of firearms Handguns(revolvers/pistols) Shoulder guns(rifles/shotgun) Cartridge single unit of ammunition with case, primer, and propellant with 1+ projectile; contained by cartridge case bullet what is expelled from the barrel Shot spherical pellets used in loading shot shells/cartridges Slug single lead projectile designed to be fired from shotgun jacket surrounds bullet core core of bullet is usually made of.. lead Class vs. individual characteristics General/measurable features that depict restricted group source (e.g. designs, determined before manufacture; rifling) Individual: random irregularities/imperfections that identify tool to toolmark What is rifling? the grooves that place the spiral spin on the bullet Lands on rifle ridges of metal between grooves in rifled bore Grooves on rifle spiral cuts in rifled bore Caliber diameter of bullet projectile (slug) Individual characteristics produced by... manufacture, wear from use/abuse Basis for firearm/toolmark identification 1. "...comparison of toolmarks allows opinions of common origin when the two toolmark contours are in 'sufficient agreement'" 2. agreement is sufficient when it exceeds the best agreement between toolmarks, consistent with agreement from tool basically the toolmarks can be matched. Identification standard summary... AFTE Theory of Identification Standard: subjective determination by qualified examiner for the amount of agreement needed for identification Objective examination can be repeated by different scientists, with the same equipment and procedures, will produce the same conclusions each time Subjective examination based on opinion; in every test/science What makes identification possible? Good examination method, skill development An individual association has be from... Practical certainty (from qualifications). NOT absolute certainty. Level 1 analysis of examination process class characteristics (can eliminate other suspects) Level 2 analysis of examination process Comparison microscopy (source of individualization) Organization for identifying Firearms (1993) National Integrated Ballistics Identification Network (NIBIN), uses computer images to assist crime labs w/ lots of data