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arson, explosives, and digital evidence study guide

Terms in this set (26)

what is the definition of arson?
the criminal act of deliberately setting fire to property
identify examples of ignition sources
open flames, sparks, static electricity, and hot surfaces
explain what happens to a combustible mixture above, within, and below the range of combustibility
above the range of combustibility
- burns away rapidly
within the range of combustibility
-explodes
below the range of combustibility
-no combustion
describe the scene at the origin of a gasoline fire
gasoline fire
char pattern moving outward from hottest spot (the origin/darker spot)
describe the scene at the origin of a low-explosive detonation
small crater, debris not far from detonation point, low energy explosion
describe a procedure for collecting and storing evidence from a suspected arson investigation
take measures to prevent contamination, document location of evidence, collect evidence at point of origin, place evidence in labeled containers for transport and preserving it, collect and preserve suitable samples, package evidence accordingly, and recognize other physical evidence on it
explain why the results of the three crystal tests for explosives have to be taken together
to get the most accurate results, time can affect the outside variables of the test
what are the three elements need to produce and sustain fire?
fuel, oxygen, heat (ignition)
is fire exothermic or endothermic? why?
exothermic because it releases heat
what is a flash point?
the minimum temperature at which a liquid fuel produces enough vapor to burn
define pyrolysis, combustion, deflagration, point of origin, char pattern, heat shadows, color of flame, and BTU
pyrolysis-the thermal decomposition of materials at elevated temperatures in an inert atmosphere
combustion-the process of burning something
deflagration-hot burning material heats the next layer of cold material and ignites it
point of origin-the start point of a fire
char pattern-the pattern of burns where a fire occurred
heat shadows-when one object blocks the travel of heat from the heat source to the substance behind the shadowing object
color of flame-flame color shows chemicals involved and the heat of the flame
btu-british thermal unit
how would odors help an investigator determine the use of an accelerant?
it can imply the use of different accelerants such as gasoline
how should an investigator manage a fire scene (7 steps)?
block off crime scene, sniff test, origin of fire, pattern of fire, determine type of fire, intensity of fire, accident or arson
what are some sources of accidental fire?
weather, wiring/electrical issues, heating systems, etc.
what are some sources of arson fire?
accelerants or deliberate causes of fire (cannot be accidental)
how do you determine the origin of a fire?
area of intense burning or the darkest spot after a fire
how many children died in the Willingham fire on December 23, 1991?
three
what did the Forensic Scientists hired by the Texas Forensic Science Commission conclude about the fire?
the fire was not arson
what is an SMTP protocol?
Simple Mail Transfer Protocol (SMTP) is an Internet standard for email transmission
what is a mail transfer agent?
software that transfers electronic mail messages from one computer to another using SMTP
define these parts of an email: message, ID, X-mailers, return-path
message-the body of an email
ID-the receiver of the email
x-mailers-the program that was used to draft and send the original email
return-path-the sender of the email
describe how you would determine where an email originated
by tracing the code from a sent email the original site can be found through the different stages the email went through before sending
what is a data aggressor site?
a website that collects all public data on people used to help advertisers target their ads
describe how geometry can be used to triangulate the location of a person using their cellphone data
the different pings on the phone towers can be used to form a triangle of where the calls were received allowing to find precise distances or general areas of cellphone use
which laws of geometry are used to do cellphone triangulation?
law of sine and cosine
define: CPU, Flash drive, Hard drive, SCSI, metadata, and USB
what is the difference between erasing data, overwriting data, and wiping a drive?
what is the process of collection and preserving digital evidence?
what is a volatile memory?
what is write-block, imaging (copying), and archiving?why are they important steps when preserving digital evidence?
cpu-central processing unit
flash drive-data stored outside of the computer
hard drive-data stored inside of the computer
scsi-small computer system interface
metadata-data that provides information about other data
usb-a computer port for uploading/downloading files
erasing data removes it from the surface, overwriting data changes the information of the data, wiping a drive completely removes the data
making a copy of the evidence in a stream account to analyze it without changing anything
computer data that requires power to be saved
write-block-stops the ability to change anything in a document, file, etc.
imaging (copying)-copying the information of a piece of data by using pictures and copies of the data to keep the data exactly as it was
archiving-saving data to a hard drive to keep it from being deleted or changed
digital evidence must be copied exactly and write-blocked so that it will not undergo any changes
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