Criminal Investigation Week 4
Finding and Packaging Evidence
Quiz on reading.
Lecture. When crime scene technicians are called to a crime scene, their primary duties are to locate and preserve evidence. Evidence is sometimes obvious and sometimes requires great creativity; however, before collecting any evidence, the investigator should think about what he is trying to prove and what defenses exist to counter the prosecution theory.
I cannot stress enough the requirement that you think before you act. Look around your crime scene and try to determine what happened, but do not lock yourself into one version of the events. Think about what the defendant will say happened and look for evidence that will counter that defense.
Does the potential defendant have a legitimate reason for being at this location, which explains his fingerprints here? Maybe, so look for latents that would be in a place where the defendant would have a hard time explaining them. Look for biological samples that could have only been left during this crime and not on a prior visit.
Could a self-defense allegation rise? Perhaps, so try to find evidence that will show that self-defense is not an issue. Use the scientific method to examine the crime scene, think about possible theories for what happened there, and then go to work to confirm or disprove each theory. On a serious and difficult crime scene, think about what other professional disciplines could be helpful.
Do you need to try to duplicate
noises that a witness heard? Maybe an
audio recording specialist could help. Are
you sure that a certain witness could have seen what he claims to have seen in
the dark of night? Go back at that same
time the next night and see for yourself, bringing someone else to act as the
target so you can describe what you saw to compare to what the witness claims
to have seen.
Does the witness say that he
smelled something peculiar? You may need
a local bioscience or chemistry professor to show you how to capture an air
sample for analysis. Could there be two
offenders where you think there is only one?
Use your talents to prove or disprove that theory. In short, think—keep thinking all the way
through your crime scene analysis and make sure that your evidence collection
is focused toward a viable theory.
After evidence is found, it must be
preserved. You may decide that a certain
portable piece of evidence is better analyzed at the lab, rather than in the
field. That is fine, but it must be
packaged in a way that will not destroy fingerprints, DNA, or other evidence during
the trip. You will not have every tool
for every packaging situation, so you must be creative. Figure out what you need to package your
evidence effectively, then look around you and see what you can use. Cut up cardboard, use string, cable ties, cotton
balls, or whatever you can find to package odd evidence. If you don’t have it, make it.
Be sure to label everything and maintain a chain of custody form. Without these, your evidence is worthless and will be thrown out of court. Photograph, diagram, explain everything in your report, and your evidence will be admissible--but miss a step and your case could be lost.
Assignment for THIS week:
Text: pp. 100 through 102