unit 2 assignment for criminalistics
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Unit 2 assignment-Evidence Collection
Shari Samson
Herzing University
Professor Michael Malmstrom
CJ300-Criminalistics
November 12, 2023
Essentially, the goal is to preserve the original integrity of the samples when packaging
evidence. “For this reason, the samples should be separated so that contamination doesn’t
happen, and all instruments, bottles, test tubes, envelopes, and other containers that were used to
package the evidence with needs to be clean and not already used” (Department of Public Safety
Texas, 2012). “It is necessary that evidence samples and standards be packaged separately. The
collection of these items must be separated by space and if possible, by time as well”
(Department of Public Safety Texas, 2012). Every package must be labeled, and a chain of
custody kept so that all the evidence items can be found easily by anyone who has been part of
the chain of custody. In solid evidence collection, the process is typically making sure that its
original condition is documented by photos before entering any crime scene. “Gloves, disposable
booties, and a face mask are to be worn when investigating a crime scene to avoid contamination
of the evidence” (Department of Public Safety Texas, 2012). Changing gloves and booties often
to avoid cross-contamination is a clever idea too.
If there is any question as to sufficiency when collecting evidence, it is way better to
collect more evidence than not enough. Every piece of evidence must be collected and preserved
separately to avoid contamination. “Each sample exhibit must be labeled to preserve the identity
and chain of custody. The evidence should be labeled with exhibit numbers on the outside of all
containers being given. The evidence should correspond to labeling and item descriptions of a
crime scene log” (Department of Public Safety Texas, 2012). At a minimum, it is recommended
that items be labeled with an item number, location of collection, date collected, and initials of
the person who collected the item. Any small evidence items should be placed in the right
containers. Every piece of evidence must be labeled and sealed properly. “For a seal to be
considered proper, the tape must have the person's initials who is performing the seal and the
date of when the seal was created. With some part of the labeling extending over the edge of the
seal” (Department of Public Safety Texas, 2012). The tape needs to cover all openings to the
evidence container. Every one of these steps is taken to make sure that if a seal has been
tampered with, it will be clear.
Liquid evidence can consist of blood, semen, and saliva to name a few. “Liquid items can
be transported in non-breakable, leakproof containers” (Schiro, n.d.) Moist or wet evidence items
from a scene could be collected in plastic containers and transported back to the evidence
receiving area if the storage time in plastic is two hours or less and this is done to prevent
contamination of other evidence. “Wet evidence, whether packaged in plastic or paper must be
removed and allowed to completely air dry once in a secure location” (Schiro, n.d.). This
evidence can then be repackaged in a new, dry paper container. Evidence having moisture, under
no circumstances, is to be packaged in plastic or paper containers for more than two hours,
“because moisture allows the growth of microorganisms which will destroy or alter evidence”
(Schiro, n.d.).
“The presence of ignitable fluids is the most commonly searched physical evidence in
arson investigations” (Fisher, Barry A.J., et al, 2012). “Because ignitable fluids are highly
volatile and evaporate easily, the proper packaging must be used to preserve these items for
laboratory analysis” (Fisher, Barry A.J., et al, 2012). Packaging evidence in paper or plastic bags
or containers won't preserve the evidence. The best way to package gas items is in clean metal
paint cans and then sealed tightly with metal lids. The other choice for storing these items is in
glass jars with metal screw-cap lids” (Fisher, Barry A.J., et al, 2012). The common types of
accelerants used in arson cases are gasoline, kerosene, charcoal, lighter fluid, paint thinner, and
turpentine (Fisher, Barry A.J., et al, 2012).
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Shoe prints and tire tracks are solid evidence. The collection guidelines for this are to
first, take one-to-one photographs using a tripod, ruler, and a level with the flash being held at
about a 45-degree angle from the surface containing an impression. “Casts can be made of
impressions by using dental stones. Once it hardens, the cast can be packaged in paper and given
to the lab” (Schiro, n.d.). Shoeprints left on hard flat surfaces can sometimes be lifted like
fingerprints. “Dust prints on certain surfaces can be lifted with an electrostatic dust print lifter”
(Schiro, n.d.).
Blood and body fluids are liquid evidence. The collection process guidelines are if the
dried blood and body fluid stains should be transported to the crime laboratory if the stained
object can. Then packaged in a paper bag or envelope and sent to the lab. “If the object can’t be
transported, then either use fingerprint tape and lift like fingerprints and place the tape on a lift
back; scrape the stains into a paper envelope; or absorb the stain onto a 1/2” long threads that are
moistened with distilled water” (Schiro, n.d.). But the threads need to be air dried before packing
for good. The threads need to be removed from the plastic and allowed to air dry once in a secure
location. For wet blood and body fluid stains, all items need to be packaged separately to prevent
cross-contamination, and “if the items can be transported to the lab, then packaging in a paper
bag or plastic bag if the time to transport is less than two hours, bring it to a secure location and
allow to completely air dry, then repackage it in a paper bag” (Schiro, n.d.). “If the items can't be
transported, then absorb the stain onto a small 1x1 square of pre-cleaned 100% cotton sheeting,
package in paper or plastic if the transport time is less than two hours, bring it to a secure
location and let completely air dry, then repackage in a paper envelope” (Schiro, n.d.).
The evidence collection guidelines for flammable fluids in gas evidence includes if
volatile liquids are located in open containers, pour a little amount of it into a clean glass vial
with an airtight seal so that way no loss will happen. Plastic containers or rubber-lined lids
should not be used. “Small samples of soil, wood, cloth, paper, etc., should be put in small, clean
metal cans and sealed immediately to prevent loss of any more volatile components by
evaporation” (Crime Scene Investigator Network, 2018). Heat-sealed KAPAK plastic is what
large pieces of wood, upholstery, wallboard, and similar exhibits that won't fit in cans need to be
placed in. In all cases, the package or container should be marked, and when exhibits themselves
can be marked, this should happen. ”Samples of flammable fluids typically present at fire scenes
should be submitted for comparison with any material recovered from partially burned
substances” (Crime Scene Investigator Network, 2018). Any samples of flammable fluids in a
suspect's possession should be given for comparison reasons, and this includes clothes, rags, or
other materials that have stains or odors that are suspicious. This is packaged the same way as
materials recovered at the scene.
The evidence collection guidelines for a seized mobile device are that the device should
be turned off, and the battery removed at once if this is possible. Doing this preserves cell tower
location information and call logs, and it prevents the phone from being used which could alter
the data on the phone. “If the device can’t be turned off, then the phone must be isolated from its
cell tower by placing it in a Faraday bag or other blocking material, set to airplane mode, or the
wi-fi, Bluetooth, or other communications system needs to be disabled” (Digital evidence, n.d.).
Antistatic packaging such as paper bags or envelopes and cardboard boxes is where digital
devices should be placed. Plastic shouldn’t be used because it can convey static electricity, or it
creates a buildup of condensation or humidity. “When digital evidence is sent to the lab, the
person submitting it needs to indicate the type of information they need, for instance, for phone
numbers and call histories from the cell phone” (Digital evidence, n.d.).
References:
Crime Scene Investigator Network. (2018
). Evidence Collection Guidelines
. Crime-
Scene-Investigator. Net. https://www.crime-scene-investigator.net/collect.html
Department of Public Safety Texas. (2012, October 16).
Physical Evidence Handbook.
https://www.utsystem.edu/sites/default/files/offices/police/policies/PEHmanuel.pdf
Digital evidence. (n.d.).
Digital evidence: How it's done
.
https://www.forensicsciencesimplified.org/digital/how,html
Fisher, Barry A. J., et al.
Techniques of crime scene investigation, Taylor & Francis
Group,
2012. ProQuest Ebook Central, https://ebookcentral.proquest.com/lib/herzing-
ebooks/detail.action?docID=1650291
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