jimtrue.com : school : CJT1110 : CH01-05: Intro to Crime Scene
Posted by Jim True on February 3, 2003 6:00 AM. Last Updated October 22, 2006 9:23 PM
Disclaimer for all material noted here is at the bottom of this web page.
HCSO.com, job opportunities at Hillsborough Co. Sheriff's Office.
Hillsborogh county, to be a crime scene technician, you have to be a deputy.
Locard's Exchange Principle:
Theory that a person cannot come into contact with an environment without collecting something from that environment or leaving something of himself behind.
Coming in contact with an environment without changing it in some way.
All Crime Scene Investigation is based on Locard's
Two types of Evidence: Testimonial and Physical
Testimonial is often tainted by cognitive processes which will alter the testimony. Testimony will change with time or exposure to other witnesses.
Physical Evidence (also called 'Real Evidence'), a tangible object.
Does not lie, cannot lie.
Two classifications of Physical Evidence:
Class Evidence - same type or 'class' of evidence, does not assume individualized.
Individual Evidence - evidence that can be related to individual characteristics of two items.
Three types of Crime Scenes:
Open Crime Scene - Outdoors, in the field, no obvious parameters of the limit of the crime scene.
Closed Crime Scene - easy to determine the actual parameters of the crime scene; inside a room, a house, etc.
Conveyance - anything that moves or could be moved.
Chain of Custody: first person who touches or collects the evidence, fills out an evidence tag and anyone that the evidence comes in contact with must log and record that the evidence was in their 'custody'. Court required proof that the evidence collected at the scene is the exact same evidence shown at the trial.
Book says two techs working each crime scene.
Two ways to work a crime scene if you're working it by yourself, minimum of two times. work it on the way in, and then work it on the way out.
Have to take the notes for the crime scene collection.
Report writing, who did what at the scene and in what sequence.
alternate path to the crime scene so as not to affect the crime scene
Petichia breaking of the blood vessels around the whites of the eyes will break during strangulation.
Use the hyoid bone to determine if strangled.
Blowflies will be on a dead body in 10-20 minutes, laying maggot eggs in open orifices.
Use the time periods and experience to establish credibility.
Work on and build on your credentials.
* Definition of a crime scene search: a planned and coordinated, legal search of a crime scene to locate physical evidence and witnesses to the crime under investigation.
Must plan the searches and coordinate them, also HAS TO BE LEGAL, otherwise everything else you find is useless 'fruit of the poison tree'.
Plain View - crime or evidence in plain sight does not require search warrant.
First Officer at the Scene - Responsibilities:
1. Arrive quickly, but safely
2. Render first aid, if necessary
3. Apprehend the suspects
4. Ascertain the extent of the crime
5. Protect and preserve the scene
6. Communicate the situation to the agency
7. Retain all the witnesses and suspect (if apprehended)
8. Record the events (what they did)
first responsibility is always 'Human Life'
Evidence and information of a fragile nature should be collected before material that is less likely to be lost or destroyed.
Fragile - shoe impressions, trace evidence that could blow away or disappear.
Seven major considerations involving crime scene searches:
1. Protection of the scene
2. Boundary determination
Always enlarge the crime scene, adding patrol car and van to the crime scene. Include your vehicles in your crime scene boundary. That way you do not have to lock the vehicles and they will be protected from the press and other visitors to the crime scene. To protect yourself and your vehicle within the crime scene.
Make sure after first officer leaves, check under the vehicle.
3. Choice of search pattern
Basic Search Patterns:
Must know what pattern you will use before starting the search. Get an overall view of the scene first and then make your plan.
No such thing as a random search in crime scene, and no such thing as a forensic backhoe for digging up dead bodies.
Crime Scene Analysis will give you an idea of who did it and how they did it. (Call this Criminal Profiling). Profile the basic person on several different fronts,
4. Instruction of personnel
5. Coordination of the personnel
6. Termination of search (one person who coordinates and ends the search)
7. Documentation
Chain of Custody starts with the first person who collects the evidence, written documentation of where the evidence was collected, who has touched it and where it has been. Has to prove that the evidence is the same evidence that was collected.
Crime Scene Integrity Sheet - Record of who comes and goes in a crime scene (the person's name and the time the person entered and left.
4 basic measurements
Baseline Method - used for long linear distances
Rectangular Coordinate - Often used the most, problem again is 90 degree angles.
Triangulation Method - Very best for measurement purposes. Don't do it off of something that can be moved. HAS to be measured from the same plane (off the corners of the same wall). EXACTLY on the money.
Scaled Drawings - NOT TO SCALE (one little error and they'll throw it out).
Plan of Action - Take Overalls of the exterior
Get to the front door and take photographs of what you can see
(Videotape it)
Alternate Light Source - ALS - Hair, fibers, trace evidence, semen, blood (photograph under the ALS) or if visible, photograph, measure, and collect.
Butcher block paper through your path into your crime scene (walking on paper, wearing booties, gloves), making a path up to the body, but cannot move the body and create a protected path up to the body.
A + B = C
Fingerprints are not fragile and ARE NOT FIRST to be collected; Fingerprints are last.
Biological evidence is never put in plastic.
Photographs must be a true and accurate representation of the evidence as you saw it.
Cameras, go with the metal bodied.
Every time you cut down the fstop, cuts the light by one half
Shutter speeds also cut the light by one half
Film Speed
Light meter + too much light, - not enough light
Depth of Field, focused at 15 feet
F/2 15-17
f 2.8 - 15-20
4 15-23
5.6 15-25
8
Wide angle 28-35 mm
Normal or standard is usually to 50mm (natural eye)
Telephoto - usually 70 to 210 or higher
Combinations 35 to 80 mm (new basic law enforcement lens)
Every piece of evidence at least 3 photographs, overall, locations and close up. (wide angle, normal eye, closeup)
photographing the glass be at an angle
Chapters 1 - 5, a lot from the book, a lot from his yakking.
Disclaimer: These are MY notes taken from classroom lectures while I'm in the classroom. While I'm perfectly happy to share my notes with my classmates and I know I take very good notes, you should still make every effort to attend the class and TAKE YOUR OWN NOTES. I will not transcribe everything the instructor says in the classroom, and I will NEVER post pre-exam reviews. My notes will not replace the value of actually attending class and taking your own class notes.I also cannot attest to their accuracy, other than they are what was provided in the lecture; you should not reference my notes as "expert opionion" by any means, and if you notice an error or omission, please do me the favor of e-mailing me with the correction and I will re-post my notes. End of Disclaimer.