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Forensics

Terms in this set (239)

Note-taking (by and or for the lead investigator) begins when the investigator is requested to report to the crime scene.
Investigator in charge assesses the scene and determines what type of documentation is required.
Note-taking begins with the first responding officer(s)!
The crime scene notes should begin with:
1) The identity of the person who contacted the investigator
2) Time of contact and arrival at the crime scene
3) Preliminary case information - including notes from the First Responder
4) Personnel present on arrival and those being contacted
Notes contain a personnel log, all observations made by the investigator, and the time observations were made.
Notes are taken in a uniform layout, concurrently as the observations are made
Notes are written in a bound notebook in blue or black ink
These days, notes can be typed at the scene using a portable device such as a tablet or laptop - if handwritten notes typed at office, original handwritten notes are not discarded!
Notes include descriptions of smells, sounds, sights, conditions (weather, temperature)
Never know what might be relevant
Investigators may choose to record crime scene notes on audio tapes.
This leaves the hands free to process the scene as the notes are taken
Tape-recorded notes must eventually be transcribed to a written document.
Officers have to be very careful about what is being said, including what others say in the background. Nothing can be deleted from the audio recording, that is like throwing away original notes
Finally, the contribution of physical evidence is ultimately determined in the courtroom
Is it admissible? - legally secured, intact chain of custody (COC), quality of testing and validity of test results, credentials of the scientist, etc?
Significance to the case at being tried?
Just as important, a person may be exonerated or excluded from suspicion if physical evidence collected at a crime scene is found to be different from standard/reference samples collected from that subject.
One of the current weaknesses of forensic science is the inability of the examiner to assign exact or even approximate probability values to most physical evidence associations.
What is the probability that a nylon fiber originated from a particular sweater?
What is the probability that a paint chip came from a suspect car in a hit and run?
There are very few statistical data available from which to derive this information, and in a mass-produced world, gathering this kind of data is increasingly elusive.
Most items of physical evidence retrieved at crime scenes cannot be linked definitively to a single person or object (lack sufficient individual characteristics).
The value of class physical evidence lies in its ability to provide corroboration of events with data that are, as nearly as possible, free of human error and bias.
The greater the DIVERSITY, the lower the chances that two matching items came from different sources.
Forensic scientists must create and update statistical databases for evaluating the significance of class characteristic matches between two items of physical evidence
When one is dealing with more than one type of class evidence, their collective presence may lead to an extremely high certainty that they originated from the same source.
At crime scene
Muddy footwear pattern
Tracks contain fibers
Tire tracks outside
Oil drips/spill on ground
Cigarette butts
From suspect
Muddy sneakers
Sneaker pattern matches footwear pattern
Fibers from suspect's vehicle
Tire pattern from car
Oil brand from car
Smokes same brand of cigarettes