crime scenes. basic reasons for crime scene reconstruction focus on key evidence provide immediate...

CRIME SCENES

BASIC REASONS FOR CRIME SCENE

• Reconstruction

• Focus on key evidence

• Provide immediate investigative leads

• Present evidence to the trier of fact

WHAT IS AT A CRIME SCENE

• Evidence of events, sequence and time

• Evidence from the suspect

• Evidence from the scene on the suspect

• Conclusive evidence

• Circumstantial evidence

• Interpretive evidence

BASIC SCENE STEPS

• Arrival issues

• Stabilization issues

• Scene security

• Boundaries

• General survey

• Overview photos and sketching

• Collection and preservation

CRIME SCENE ARRIVAL

• Safety of responding personnel• Check the medical condition of the

victim• List all responding units• Prevent loss of evidence due to:

– Medical aid– Suspect action– Environmental issues

STABILIZE THE CRIME SCENE

• Protect the perishable evidence• Exclude all uninvolved personnel• Be aware of what can damage evidence:

– GSR– Heat on biological– Alcohol in the body

• Isolate the participants• Effects of weather

CRIME SCENE SECURITY

• Use tape or guards

• Purpose is to restrict access to select few

• Log who enters and leaves the scene

SET CRIME SCENE BOUNDARIES

• Better to over estimate

• Consider entry and exit

• Focus on three dimensions

ASSESS THE CRIME SCENE

• Who needs to be notified– Supervision– Coroner– Crime lab– Sheriff/city investigators– Specialized assistance

• What is critical for immediate processing• Set priorities

JOBS IN PROCESSING SCENE

• Photos/video

• Fingerprints

• Note taking

• Bagger/tagger

• Collector

• Security

GENERAL SURVEY

• Limit to one or two persons

• Note likely entry/exit points

• Note misplaced, foreign objects

• Note locations of prints/trace

• Prevent contamination

• Organize

ORGANIZE

• Designate trash areas, command center, smoking areas, equipment areas

• Where is the command center, restrooms, food/drink, phones

• If night is approaching, how much will be done

• Order of processing

SCENE DOCUMENTATION

• Photography

• Sketches

• Note taking

PHOTOGRAPHY

• Orientation/overalls– Outside and inside– All directions– All four walls/ all rooms– Doors/ windows– Orientation of evidence with and without

labels– Close-up

ORIENTATION

• LOCATION ORIENTATION

• FRONT/SIDES/BACK OF BUILDING

• 360 DEGREES FROM EACH SIDE OF BUILDING

• 45 DEGREES FROM CORNER OF BUILDING/AREA

360 Degree Overall

EVIDENCE LOCATION

• AS IS

• ORIENTATION/ MIDDLE/ CLOSEUP

• MARKERS

• ORIENTATION/MIDDLE/CLOSEUP

• BEFORE AND AFTER SHOT WHENEVER SOMETHING IS MOVED IN ORDER TO SEE ITEM

NOTE TAKING

• Detailed

• Chronological

• Information such as date/times– Scene description– Items collected, date, and times– Body descriptions– Etc..

CRIME SCENE SKETCHING

• Definition: The rough notes and measurements one takes at a scene which shows the key physical measurements of the scene and its evidence location.

• Purpose– To document relationship of evidence– To illustrate to others the crime scene– To provide an overall perspective of the scene

CRIME SCENE DIAGRAMS

• A diagram is the finished product that is included in the report and/or presented to an audience.

• This diagram can be:– Scaled or un-scaled– Hand drawn– Computer generated (CAD)– Animated 3D video clips

Basic Tools for Field Sketching

• Tape measures - Preferably Inch/Metric combination

• Protractor• Level and string line• Compass with sighting capability• Others such as Optical range finders. Reel

measurement, Transits etc.

SKETCH TYPES

• Rectangular

• Triangulation

• XY coordinates

• Angular displacement

• Grids

• Elevations

• Cross-projections and 3 D

Rectangular Coordinates

• This consists of measuring the X and Y distance from two reference points or walls.

• If one is going to plot the data on a computer, this is the preferred method.

1

Triangulation

• A method of measurement traditionally taught to crime scene personnel

• Measurements are made directly to each of two permanent reference points

• Must have a baseline measurement between the reference points.

Pole A Pole B

191'138' 57'199' 59'

60.5'202'145' 113'

99' 200'73' 147'4"74' 11" 147' 4"

165' 10'

158' 8"65'30'

Baseline with Distance Only

Polar or Angular Coordinates

• Determine one reference point

• Measure items from this reference point by angle and distance

• Usually used for outdoor scenes

XY Grid Techniques

• Set up a grid of lines of arbitrary size, can be 6”, 1’, 3’ square.

• Generally use numbers on one axis and letters on the other. This minimizes error.

• This technique is good for multiple evidence that would be too detailed to record by individual points, such as grave sites, bombings, airplane crashes.

XY Grid PictureThe Grid System for Many Items

1311109876 1254321AB

CDE

FG

HIJKL

MN

14 15 16 17 18 19

Transecting Baseline or Straight Line Coordinates

• Items are measured as above or below a baseline.• Usually used in outdoor scenes.• Used where the evidence is along a line and it is

easier to create an arbitrary baseline in order to simplify the measuring routine.

• Use one tape for the baseline and the other for the transection distance

A B

32 7/8'

26 7/8'

33 5/8'

36 5/8'

63 7/8'

71 1/16'40 1/16'

11 7/8'

57 3/8'

75 1/16'

Sketching Elevation

• Sketching in the outdoor environment can bring forth unique problems.

• One has to be able to illustrate elevation or contour change for a varying exterior scene.

• Tools for this technique can be a string line and level (Brick layer) or a Lock/Abney type level level.

• Usually one contour diagram is sufficient.• Making elevation measurements allows for 3D

diagramming.

Elevation Measurments

LevelLine

Measurements of elevation over uneven surfaces

Exploded Views

• This technique has the walls laying flat and attached to the floor plan.

• It makes it easier to relate measurements and evidence location to the adjacent floor.

• Problems that this can cause is that it can take up a lot of room on a sketch pad

SEARCH AND LOCATE EVIDENCE

• Flag into entry areas

• Be systematic

• Mark, record, and collect

• Packaging and labeling

• Order of collection

• Preservation

• References

WHAT HAPPENED?

• Likely theory

• Why?

• Alternative theory

• Where is pt of entry/exit?

• What are sources of contamination?

WHEN DID IT HAPPEN?

• Record items like:– Light switch positions– Window/door positions– Curtain positions– Mail/newspaper– Dress of victim

WHEN DID IT HAPPEN?

• Insect activity

• Rigor mortis

• Livor mortis

• Body temp

• Vitreous

WHY DID IT HAPPEN?

• Motives

• Signs of struggle

• Sign of burglary

• Breaking and entry

WHAT DID SUSPECT LEAVE BEHIND?

• Near body

• Point of entry/exit

WHAT DID SUSPECT REMOVE?

• Property

• Trace

• Physiological fluids

• Exemplar collection

WHAT TYPES OF DEFENSE ARGUMENTS TO EXPECT?

• Accident

• Suicide

• Homicide

• The other guy did it