Lecture 3: Crime Scene Analysis

Question 1

Processing a firearm crime scene steps

Answer 1

1. Identify Evidence
2. Notes & Sketches/Documentation
3. Measurements
4. Establishing Trajectories
5. Chemical Tests (GSR)
6. Initial Opinion

Question 2

needs in a firearm crime scene

Answer 2

positions of injured
bullet position & cartridge
position of bullet damage and recovered bullets
position of shooter

Question 3

notes to remember in collecting firearm evidence

Answer 3

they are durable (ie. can have finger prints, DNA, hair evidence)
remembering safety
photograph and document

Question 4

notes of firearm analysis

Answer 4

safety check everything
no live rounds
preserve any other evidence removed

Question 5

setps of a gun firing

Answer 5

1. ammunition pushed into chamber
2. hammer cocks
3. trigger pulled and hammer releases
4. hammer strikes firing pin which ignites the primer
5. primer (through the flash hole) then ignites the propellant pushing the bullet through the barrel
6. bullet exits along with many gasses in the gun

Question 6

what happens when a bullet hits glass

Answer 6

fracturing at point of impact

Question 7

what is the coning effect

Answer 7

where the caves on the other side of impact and the shards of glass are spread there

Question 8

what is a secondary projectile

Answer 8

a object that was impacted by the bullet and is turned into a projectile possibly injuring or damaging another

Question 9

what is a trajectory rod

Answer 9

a trajectory rod is used to visually represent the point of impact and direction of trajectory

Question 10

what info should be gathered about the bullets

Answer 10

the # of shots fired, the type of weapon and the caliber of the weapon

Question 11

what are some possible reasons for no cartridge cases

Answer 11

not self loading (revolver), picked them up, too spread out, is a rifle

Question 12

how are bullets examined

Answer 12

visually examined

Question 13

features on a bullets for IDs

Answer 13

headstamp, manufacturer, caliber, dealer, manufacturing date and type of firearm

Question 13

indication of bullet being fired

Answer 13

rifling pattern, impact damage, firing pin mark, inside of the cartridge is black, ejector/extractor mark, breech face

Question 13

first thing to do when arriving on a scene

Answer 13

general assessment: walk through, making a plan, noting transient and non transient evidence

Question 14

where is the most common places that the cartridge cases fall

Answer 14

to the right of the right back

Question 14

after a walkthrough of the scene a forensic investigator continues to

Answer 14

photograph and document all of the evidence present

Question 14

after taking photographs of the scene what is the next step

Answer 14

ID marking the evidence, accurate measurements of all, collecting cases

Question 15

after IDing all the evidence at the scene what is the next steps

Answer 15

it is to locate all bullet damage (bullets, bullet fragments, secondary projectile) and ID them with trajectory rods

Question 15

after IDing the bullet damage the last step of processing a firearm scene is

Answer 15

doing a sodium rhodizonate test for GSR, also looking for bullet wipe

Question 16

expert info needed before leaving the scene

Answer 16

minimum shots fired, caliber, type of weapon, trajectory

Question 17

what kind of tools is need in handling firearms

Answer 17

plastic as to not damage the weapon or any other evidence

Question 18

when handling a gun avoid:

Answer 18

losing GSR (unnecessary handling), dropping the gun, and metal tools

Question 19

Safety First, what should be done when a firearm is found

Answer 19

examined for live round, unload gun if live