forensic science chapter 2

what happens upon arrival at a crime scene to the first responding officer

1) acquiring medical assistance for injured victims

2) detained any witnesses or suspects

3) secure the crime scene

4) call for other investigators or other officers

why is it important to keep an entry log of when people enter and exit the crime scene

so that no evidence or the scene is not tampered

what is physical evidence

can be anything from massive object to microscopic physical objects

what are the three methods for recording a crime scene

photography, sketching, and note taking

how should someone take notes?

when the investigator is contacted and requested to report to the crime scene, the identity of the person who contacted the investigator, time of contact and arrival at the scene preliminary case information, personnel present on arrival and those being contacted, things that cannot be confirmed in pictures like the weather and smell

what three photos do you need

far away, medial, and close up with a ruler by its side

what is the walkthrough or initial survey of the crime scene

perpetrators point of entry and exit are located; indirect path is taken to the center of the crime scene, obvious items of evidence are located and documented, the conditions of the scene are observed and recorded

what are the different types of crime searches

line/strip, grid, spiral, wheel/ray, quadrant/zone

describe the line strip search

one or two investigators start at the boundary of the crime scene and search in straight lines across to the other side of the crime scene

describe the grid search

two or more investigators form a grid by searching in line patterns that overlap and are perpendicular

spiral search

one investigator searches in a spiral path from the center of the crime scene to the boundary or from the boundary of the crime scene to the center

describe the wheel/ray search

several investigators search in straight lines from the center to the boundary or from the boundary to the center

describe the quadrant/zone search

the crime scene is divided into smaller sections and one or more investigators are assigned to search each zone

what must be in a rough sketch

clear layout of the crime scene, clarify object and feature already described in notes or shown in photographs, illustrate the relationship in space of all significant items and features, show measurements over long distances and topography of outdoor scenes, depict possible of entry, exit, and movement through the scene, title block with information of the case, crime scene, person creating the sketch legend with identity and dimensions of objects in the sketch, compass showing the north direction. body containing the sketch itself and two point of reference for objects and the distance between the points and the object

what is required in the finished crime scene sketch

drawn to scale with care and concern for appearance usually with computers for the creation of three dimensional finished sketches

how can physical evidence be tampered

through contamination, breakage, evaporation, accidental scratching or bending, or though improper packaging

what is most important to wear to a crime scene

a hazmat suit, latex gloves and disposable forceps and sanitized equiptment

what should you use for biological evidence

brown paper bag

hair, glass, fibers, and various other kinds of small or trace evidence should be in what

unbreakable plastic pill bottles with pressure lids

what should you use when packaging find powder

the druggist fold

what should you use for arson scenes

airtight metal or glass containers to prevent the loss of accelerant vapors

why can’t you put wet material in airtight containers

because the growth of mold

what is chain of custody and why is it important

it lists of all persons who came into possession of an item of evidence and it is important because it kept track of evidence so nothing can be tampered

what are the four court approved seizure and search without a warrant

1) the existence of emergency circumstances

2) the need to prevent the immediate loss or destruction of evidence

3) a search of a person and property within the immediate control of the person provided it is made incident to lawful arrest

4) a search made by consent of the parties involved

what was the significance of the minced vs arizona case

it was a four say search at a homicide scene and determined that the evidence was illegally seized beavsue a warrant was never issued and the circumstances of the case did not justify a warrant less search

what was the significance of the michigan vs tyler case

a fire destroyed a business establishment leased by tyler and a business partner and the court decided that the evidence obtained from the initial search was legally seized but evidence search 4,7, and 24, days after the incident were illegally seized