Processing a Crime Scene

Crime Scene Mapping: 4 Types

- Baseline - Rectangular Coordinates - Triangulation - Polar/grid coordinates

What should written documentation include?

- which superiors were notified - arrival info (date, time) - scene description - victim description - crime scene team members

Advanced Mapping Techniques

-Able to provide precise electronic distance measurements -useful in mapping large-scale sores -GPS -laser mapping equipment available

Sketch perspectives

-Bird's eye or overhead -elevation or side view -3D view (show side walls and floor) -cross-section or exploded view (multiple perspectives incorporated to vie a clearer picture of the scene)

Although all crime scenes are different, the same general procedures should be followed

-Initial scene assessment -search for and recognize all physical evidence -documentation of physical evidence -collection of physical evidence -packaging and preservation of physical evidence -crime scene reconstruction

Sketching

-accurately portrays physical facts and establishes precise locations -helps create a mental picture for those not present -assists in interviewing and preparing reports -can be used in court as a visual aid -make sketches of all serious crimes and accident scenes AFTER photographs are taken

Taking Notes

-can be done by hand or on an audio tape that is transcribed later -take detailed notes so any observations made at the scene can be recalled correctly - record things you don't find (that you think you should) as well as things you do find ex. find a dead body w/one earring and the other earring is not at the scene. Location of other earring could be important

Photography guidelines

-document all known evidence -if more evidence is found, return and document fully -use photos to demonstrate the results of additional analysis (such as developed fingerprints) -always use a photo placard as 1st photo - do not include yourself or others in photos -always use the photo log - make sure the scale is on same plane as object -shoot w/subject matter parallel to camera plane (not an angle) -when in doubt, photograph!

Midrange/Evidence-Establishing

-frames the evidence w/an easily recognized landmarks -establishes position of evidence within scene -a scale is never included (not meant to show intricate details, only position/orientation)

Polar/grid coordinates

-measurements taken from 1 fixed point -a distance and an angle are recorded for each item -method is most useful in large outdoor scenes w/ very few landmarks

Triangulation

-most accurate method w/out using tech -each item measured in 2 points from 2 fixed points -eliminates 90 degree angle issue of previous methods -if item is not a fixed shape, the measurements are made to approx. center of mass

Baseline

-most basic and least accurate method -baseline constructed between two points of fixed, known location -measurements taken from baseline to center of mass or nearest edge of object -quick and easy to use, but difficult to ensure a 90 degree angle from baseline

Overall

-often taken w/a wide-angle lens -taken from each corner of the room or frown each direction (N,S,E,W) -sometimes necessary to photograph area surrounding the scene

Final/finished Sketch

-prepared for courtroom presentation -drawn to scale -produced in ink or on a computer -only significant items are included to reduce clutter -include all measurements for those items -include a legend

Rough Sketch

-prepared onscene -not drawn to scale -prepared using any writing instrument (pen, pencil, crayon, etc.) -used to record measurements and distances of ALL items

Rectangular Coordinates

-slightly more accurate than baseline method -uses two baselines -2+ measurements may be taken of various points on the same object -difficult to ensure 90 degree angle -useful in confined spaces

Close-up/Comparison/Examination

-used to show evident detail -evidence should fill the frame -taken w/and w/out a scale --take without the scale first to prevent accusations of scene tampering -the use of scale enables life-size reproductions if necessary

Three ranges of crime scene photographs

1. Overall 2. Midrange/Evidence-Establishing 3. Close-up/Comparison/Examination

Sketch

a permanent record of the size and distance relationship of the crime scene and related evidence

Crime scene photographs

must be fair and accurate: should show the questioned area or object in its most natural state

Crime Scene Mapping: Use

record crime scene measurements