lab exam - readings Flashcards
sentence for a first offence of driving under the influence (alcohol)
3-day licence suspension and 150$ administrative fee
sentence for a second offence within 5 years of driving under the influence (alcohol)
7-day licence suspension, mandatory alcohol education program, and 150$ administrative fee
sentence for a third offence within 5 years of driving under the influence (alcohol)
30-day licence suspension, mandatory alcohol treatment program, six-month ignition interlock licence condition, and a 150$ administrative fee
what is ALCOScreen
saliva alcohol test
what does ALCOScreen react with
methyl, ethyl, and allyl alcohols
what enhances colour development in ALOScreen
peroxides and strong oxidizers
what inhibits colour development in ALOScreen
ascoribc acid, tannic acid, pyrogallol, bilirubin, etc.
difference between drug screening and identification
screening: looking for one drug in particular
identification: multiple tests to determine the exact composition of an unknown compound
what percentage of collected forensic evidence is drug-related in the US
nearly 75%
how long does a strand of hair retain evidence of drug use
at least three months
who is James Marsh
a Scottish chemist who developed a chemical test to detect arsenic
what type of drug is marijuana
hallucinogen
what happens when you pull the trigger of a modern handgun
the firing pin hits the primer cap, creating a small explosion which detonates a powder charge inside the cartridge. That explosion releases a tremendous volume of gas which creates the forcing cone, pushing the bullet out of the barrel
what type(s) of gun(s) don’t impart a twist
shotguns and smooth bore rifles
what are lands and grooves
lands: indentations in the barrel, creating raised areas on the bullet
grooves: raised areas in the barrel creating cut out areas on the bullet
true or fasle: If a bullet is dropped from the same height. and at the same time. another identical bullet is fired from a gun whose barrel is parallel to the ground. the fired bullet will land at least a second after the dropped one
false, neither the spin of a bullet as it emerges from the barrel of a gun nor its velocity give it any lift. the fired bullet will be acted on by gravity the same way as the dropped bullet, and both will hit the ground at the same time
true or fasle: Any caliber cartridge can be fired from a gun made for a bigger cartridge. for example: a . 357 round can be fired from a .44
false, because the mechanism of the bigger gun is not designed to work with smaller calibers, the gun will not fire, eject, or load a round safely
true or false: only the US Government normally has access to a gun totally invisible to X-ray scanners in airports
fasle, no gun is totally invisible to X-rays in airports
true or false: a gun fired underwater is lethal for between six and ten feet
false, the density of water robs bullets of their energy after three feet
what are the five things hairs and fibers allow us to do (forensic pov)
- link a suspect to the scene of a crime
- determine the entrance or exit route of a criminal
- show that contact has occurred between a suspect and a victim
- identify clothes or shoes disposed of by a suspect
- determine the contact point of a victim with an object, like a car, or a table edge
what characteristics do we look at in hair analysis
colour, length, diameter, shape
how can hair be distinguished from fibers
fibers have no medulla or scale pattern
what characteristics are included in fiber analysis
colour, length, diameter, cross-sectional shape
how to collect fibers at a scene
with forceps (if can be seen with the naked eye) vacuum fitted with a special filter sticky medium (like tape)
