ok, so i understand the reasons behind evidence markers, but how do you know where to start? like in the episode turn of the screw, when they got done with cataloging the evidence, it seemd like all the evidence markers were all over the place, with no definable starting point. and another example, if you have spots of blood on the floor, but they're all close together, but not in a straight line, how do you know which drop of blood to place the first marker next to? see its the little stuff like that i have trouble understanding. do they explain why you have to do things a certain way in the textbooks?
The evidence markers are numbed so they catalouge it by the number, for the blood the first blood drop will be the bigest and the las will be the smallest so you find the biggest and then look at the direction and you will then find the smallest
hmm ok well that makes sense...so thats partly why they do the walkthrough? to figure out exactly where everything started and they place the markers accordingly?
Yes, When we do a walkthrough we look and see if me have missed anything document the evdience, lift footprints and fingerprints etc... Happy to help!:devil:
It really doesn't matter where you start working at a crime scene. Ideally, if you're aware of what appears to be the suspect's entry point, you start there by placing numbered evidence location tags next to apparent items of evidence (footprints, tire tracks, pry marks, broken windows, spots of blood, etc etc) , photographing that evidence (with the tag showing in the photo) and noting the relevant info on your evidence location list and scene sketch. At a typical homicide crime scene, you might lay out 200 evidence location tags that identify things of interest at a crime scene, but then only actually collect 100-150 of those items. For example, you might place a numbered evidence location tag next to each of five apparent bullet holes in a building wall ... giving them a numerical reference on your scene sketch ... but you probably wouldn't cut that portion of the wall out of the building and 'collect' it. The number on any particular evidence location tag is simply that: a reference number. It has no other significance or relevance in terms of sequence-of-appearance, etc. As for walk-throughs: you would normally conduct a walk-through at the beginning of your investigation (especially if there is more than one CSI at the scene), making sure you have a sense of the entire scene and taking the time to properly ID/preserve/protect 'fragile' evidence, and then conduct a final walk-through at the end of your investigation, using your located evidence list and scene sketch to make sure you collected all of the evidence you wanted to collect!