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.


Reading Assignment for THIS week:

Text: pp. 100 through 102

Officer's Evidence Manual

Yes, I know this is a very long manual, but you don't need to read all of it.  Search through it for all the places that mention packaging and storage and read those.


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Christopher Bruno