2Learning Goals: Understand the importance of diagrams. Know the two methods of measuring objects at a scene.Perform measurements and complete a diagram of a scene.
3Crime Scene DiagramsDone for serious crime scenes and major accidents.Augments pictures and notes / reports.Simple, clean, line drawings that indicate the positions of evidentiary objects in relationship to fixed objects at a scene.Diagrams allow for measurements (unlike pictures).
4Crime Scene DiagramsExcellent visual aid which selectively includes significant objects and leaves out unnecessary details.Will clarify the appearance of the scene and make it easier to comprehend.Admissible in court and are often used in big blow-up charts.
5Crime Scene DiagramsPhotographs may not be enough to sufficiently record a scene.Photographs create a different perspective and do not always depict the exact location of objects or their relationship to each other.Photographs do not show measurements or true distances.Photographs may have distortions.
6Crime Scene Diagrams Refresh the memory of the investigator. Refresh memory of the witnesses.Refresh the memory of the cooperative suspect (who may assist with further details regarding the scene).Develops a clear understanding of events.
7Crime Scene Diagrams More descriptive than hundreds of words. Can show sequence of events.Can show trails and patterns of movement.
8General Rules for Diagramming Show all objects that have a bearing on the crime scene.Locations of entrances / exits.Show which way the door opens / direction of swing.Location of weapons / evidence relative to the victim and stationary objects.Windows.
9Methods of Measuring Rectangular Coordinate (Baseline Method) Used indoors.Use a baseline that is fixed and permanent (wall).Measure items using a 90 degree angle from the baseline.
10Methods of MeasuringTriangulation Method (creation of a triangle of known distances)Primarily used for outdoors.Used two fixed points of reference.Measures the object from the two fixed points. (which creates the triangle)Can have any degree of angle.May have to establish a secondary fixed point. (drive a spike into the ground)
11Methods of Diagramming Overview Projection (most common)
12Methods of Diagramming Cross Projection (Used to gain three dimensional perspective
14Items to be MeasuredMeasure at least 2 points on an object to be able to properly place that object back into a scene.A human body will need at least 6 points of reference to be placed back into a scene (head, hands, feet, torso)
15Items to be Measured Depends on the object measured. On a tool or small item, measure to the edges or points.On a body, measure to the center mass of a particular body part.
16Three Types of Sketching Sketch of Locality (gives a picture of the crime scene and it’s environment, i.e. neighboring buildings and roads)Sketch of Grounds (gives a picture of the scene with it’s surroundings, i.e. a house with it’s property outlined, an office within an entire floor plan)
17Three Types of Sketching Sketch of Details (description of crime scene within it’s immediate surroundings, i.e. the room in which the crime was committed)
18Diagrams Should Include: Case number.Address or location descriptor.Date/Time.Officer name/serial number.Type of offense.Victim’s name.Entrances/exits/windows.
19Diagrams Should Include: Size of scene.Indicate north with “N”Show all measurements.Include a key or legend.Include a disclaimer of “not to scale” unless working with precision instruments.
20DiagramsMay be performed by patrol officers on collision investigations, natural death investigations, and/or other cases that need it or where someone requested to have it.
353D Scene Digitizer Costly to buy. ($44,900) Sets up on tripod. Measures roomup to 40 ft.
363D Scene DigitizerCan create a “wire-frame mesh”. (3D model of a scene)
37Technological Advances Reasons why advanced tools are not in use:Prohibitive costs.Time to train.Tech overload.Prediction: Hand-held or portable devices will measure and diagram scenes quickly and efficiently and lessen a detective’s workload.Pen and paper will be done away with and a machine will do the drawing of scenes.
38Artist’s sketch of scene Shows detailEliminatesobscuritySketch artists can replicate the scene and clear up some of the details that appear obscured in photos.
39Things to Remember: Decide what is to be sketched beforehand. Don’t sketch until familiar with the scene.Leave out objects not relevant to the case.Include only essential information.
40Things to Remember:Your diagrams will not be exact, they will be approximate.Rough sketch to be included with the case file as well as the finished copy.
41Errors when Diagramming: Measuring a distance by pacing and then recording results in feet and inches.Relying on memory alone.Correctly outlining the dimensions of a room and then placing objects within by mere visual means (no measurements).Not being able to read your measurements.Improper measuring device or technique.
42Practical ExercisePractice measuring objects within the classroom using the methods given in class.