What is rifling and what is its purpose?
The spiral grooves impressed upon the bore of the barrel to give spin to a bullet
What are grooves and lands?
The cuts of the rifled bore
Lands are the higher portions while grooves are the lower portions
What are striations?
Marking impressed into the metal of the barrel
How are striations useful for comparing bullets?
No two rifled barrels have identical striations
How does a shotgun barrel differ from the barrel of a handgun?
A shotgun isn't rifled
Has a smooth barrel
Describe the relationship between a shotgun's gauge and the diameter of its barrel
The higher the gauge the smaller the diameter of the barrel
Briefly describe the sequence of events that occur from the time the trigger of a firearm is pulled to the time the bullet is fired
The act of pulling the trigger releases the weapon's firing pin, causing it to strike the primer, which ignites the powder which has expanding gases from the burning gunpowder propel the bullet
What parts of a firearm leave impressions on a cartridge case that constitute individual characteristics of that weapon?
The firing case, breech block, ejector and extraction mechanism
What is NIBIN
National integrated ballistics information network
What is distance determination and upon what is it based?
Determining the distance between a firearm and its target and it is based upon the distribution of powder patterns or shot/pellet distribution
What is bullet wipe?
Dark ring formed around the perimeter of an entry hole wiped off a bullet's surface as it passes through
What is the Greiss test and what substance is being tested for in this procedure?
Chemical test used to develop patterns of gunpowder residue around the bullet hole
Tests for nitrates
Why should a suspect firearm never be picked up by inserting an object into its barrel?
This practice disturbs the powder deposits, rust, or dirt lodged in the barrel and may alter markings in the barrel
How should a suspect weapon discovered underwater be transferred to the library and why?
In a receptacle containing enough of the water in which the weapon was found to keep it fully submerged
To prevent rust from forming
What typically imparts individual characteristics to a tool mark?
The process used to cut the barrel along with nicks and breaks caused by wear and tear
How does the criminalist record a tool mark for comparison when removal of the original tool mark is complicated?
Photographs the marked area and make a cast of the area
What is SICAR and how is it useful in comparing impressions?
Shoe print image capture and retrieval
Incorporates multiple databases to search known and unknown footwear files which makes it useful for comparison of shoes
Which of the following is NOT expected to show any evidential marks or impressions?
A shotgun pellet
Which of the following procedures is NOT to be followed in collecting packaging firearms evidence at the crime scene?
Marking an empty cartridge case on its base for identification
Two elements detected on the hands of an individual who has recently fired a weapon are:
Barium and antimony
Which of the following is LEAST likely to be considered by the examining tool mark technician?
The brand name of the tool
Which of the following results is NOT possible from a laboratory examination of firearm evidence?
Identifying a bullet as having been combined with a particular she'll before being discharged
The most important instrument for comparing bullets is the ___________.
Comparison microscope
The diameter of a shotgun barrel is expressed by the term _______.
Gauge
As a rule of thumb, the spread in the pattern made by a 12-gauge shotgun increases one inch for every ________ of distance from the target.
Yard
A(n) ________ is any impression caused by a tool coming into contact with another object.
Tool mark
Shoe and tire marks impressed into soft earth at a crime scene are best preserved by _________ and ________.
Photography and casting
Firearm (evidence collection of a bullet)
The investigator must protect the bullet by wrapping it in tissue paper before placing it in a pillbox or an envelope for shipment to the crime laboratory
Tool marks
(What shouldn't crime scene investigator do and why when examining tool marks?)
Under no circumstances must the crime scene investigator attempt to fit the suspect tool into the tool mark
Any contact between the tool and the marked surface may alter the mark and will, at the least, raise serious questions about the integrity of the e
Points of comparison
(What kind of marks have been useful in homicide and rape cases)
Bite mark impressions on skin and foodstuffs have proven to be important evidence in a number of homicide and rape cases
What is a questioned document?
Any object that contains handwritten or typed markings whose source of authenticity are in doubt
Describe two situations in which a document examiner may be prevented from coming to a positive conclusion about a questioned document.
When an insufficient amount of known writings are present for comparison
Questioned document contains only a few words or is deliberately written
What are exemplars? Why are they important for document examination?
Authentic samples of an individual's writing used for comparison to suspect samples
Find irregularities between exemplar and questioned document (comparison)
Name five important characteristics of a printer, photocopier, or fax machine that a document examiner must identify when analyzing a document in a situation where the suspect machine is not available.
The printing technology
The type of paper
The type of toner or ink used
The chemical composition of the ink or toner used
The type of fusing method (ex ink or laser)
List the most common features associated with paper examination
General appearance
Color
Weight
Watermarks
Define natural variations
Normal deviations found between repeated samples of an individual's handwriting
Define indented writings
Impressions left on a paper positioned on a paper below the one written on
Why might a traced signature be more easily detected as a forgery than one that is copied free hand?
People don't have the same signature every time due to natural variations
List three characteristics of exemplars that should be alike as possible to the questioned document
The type of writing implements used
The type of paper used
Whether the paper is ruled or unruled
What is a graphologist (what do they try to do)?
Graphologist- attempts to predict character traits from handwriting examination
Three characteristics of a proper handwriting sample
The subject should not be shown the questioned document
The subject is not told how to spell words or use punctuation
The subject should be asked to sign the text always have a witness