Crime Scene Processing Series CRIME SCENE DIAGRAMMING New Mexico State Police

1. Crime Scene Processing Series CRIME SCENE DIAGRAMMING New Mexico State Police Criminal Investigations Section Crime Scene Team

2. Learning Objectives • Understand the purpose for preparing a diagram • Identify the information that must appear on a diagram • Demonstrate knowledge and proficiency in various methods of incident scene diagram

3. Why do a Crime Scene Diagram? • It establishes a permanent record of the scene • Associates evidence with the scene • Supplements photographs • Useful in orienting a person to the scene • Witnesses can look at a diagram without being prejudiced…you can’t show witnesses photos • Useful in Court • Easily blown-up for presentation • Not prejudicial to the jury

4. Why do a Diagram, cont. • The draw back of photos is that that they are a two- dimensional representation of a three dimensional object • Most photos distort the relationship of the photographed objects, causing items to appear closer or farther apart than they actually are • The sketch is a bird-eye view, which is hard to get with a camera

5. Methods • Grid (X/Y) Coordinates • Triangulation Coordinates • Polar Coordinates • Raw Measurements

6. Grid Method • The scene in divided into four quadrants • Each item is measured at right-angles from each axis • This is a great method because it is easy & efficient

7. Grid (X/Y) Method Y axis X axis (origin) The grid can also be expressed as north, south, east, and west measurements

9. Grid (X/Y) Method

11. Baseline Method • Place a single line, dividing the scene in half • Measure relative to the line • Alone the baseline • At a right-angle to the baseline • Great for a diagram where you have no fixed reference points

12. Incident: Bone Scatter, Death Investigation Location: Chavez County, NM Date: 3/3/07 Drawn by: R. Mathews Not to Scale REF. PT. 1 N: 32 degrees 41.292’ W: 105 degrees 13.951’ skull Leg bone torso North Leg bone N Arm bone Trees Arm bone Dry stream bed Ref. PT. 2 N: 32 degrees 41.317’ W: 105 degrees 14.003’ N

13. Triangulation Method • Straight line distance measured from two (2) reference points • The item of evidence will be at the intersection of the intersection of the two (2) arcs • This is a very accurate method of measuring

14. Triangulation Method

15. Polar Method • Straight line distance measured from a fixed reference point • Measure the distance from the reference point to the item of evidence • Document the line’s azimuth from the fixed reference point to the item of evidence • This is the best method for determining elevations above/below a fixed reference point

16. Polar Method North 12 ft @ 120 degrees 18 ft @ 100 degrees

17. Raw Measurements • The physical dimensions of a room/area • You should do this on every diagram to complement the main method of measurement • Width of roads • Distance from the victim’s hand to the gun • Overall dimensions of a room

18. Raw Measurements

19. Information added to a USGS Map

20. Sketching the Crime Scene • Equipment • Measuring tapes, rulers • Hammer, nails, shop clamps • Laser range-finder • Graph paper and PENSILS (avoid using a pen) • GPS • Maps, blue-prints, aerial photos • Accident/crime scene templates

21. Sketching the Crime Scene • Its usually prepared in one of two ways • Bird’s-eye-view (straight down) • Elevation (cross section) • Try to maintain proportionality (scale) • Double-check your measurements to be sure that they are correct • Especially important if calculations will later be used • Bloodstain pattern analysis • Accident reconstruction • Shooting scene reconstruction

22. Sketching the Crime Scene • Crime scene diagram is similar to diagramming an auto accident with injuries • Use fixed reference points and reference lines • Diagram the location of all evidence, including the body • Diagram the location of the head and the feet if practical...otherwise, diagram the location of the center-of-mass • If you start a diagram & need to leave, make sure you pass on the responsibility to another person

23. Rough Draft

24. Finished product

25. Sketching the Crime Scene • Use the rough-draft to make a finished (court admissible) product • Hand-drawn is fine if you are a good artist • Use black ink and good paper • Use a template • Computer generated sketches are preferable • Can be easily reproduced without loss of quality • Can be easily blown-up or added to Power Point • Maintain the original, rough sketch • It is discoverable-just like your other field notes

26. Things to put in the Legend • Specific location of the scene • Address, GPS Coordinate, etc. • Date/Time • Case Number • Preparer • Scale (or scale disclaimer ) • Compass Orientation (North Arrow) • Evidence Numbers • Measurements

27. Court room presentations

28. Court room presentations

29. Court room presentations

30. Court room presentations

31. Court room presentations

32. Questions?