Gardner IAI
Mechanical Fit
"fracture matching" is where an item is damaged and pieces are deposited in the scene. Because the breakage is random it makes it possible to individualize a specific piece to a specific item. p. 26
Methodology employed in bloodstain pattern analysis...The technician:
* Becomes familiar with the entire scene * Identifies the discrete patterns among the various bloodstained surfaces * Categorizes these patterns based on the established taxonomy of bloodstain pattern analysis * Evaluates aspects of directionality and motion in the stain or pattern * Evaluates interrelationships among stains, patterns, and other evidence * Evaluates angles of impact, points of convergence, and areas of origin (if necessary) * Evaluates viable source events to explain the pattern (based on all of the above)
methodolodgy for crime scene investigation from O'Hara:
*Painstaking, comprehensive collection of data *Arrangement and correlation of that data *Definition of issues and investigative questions *Development of a hypothesis along the lines of the available data and subsequent resolution of any hypotheses 8testing of the hypothesis and elimination, when possible, of contradicting hypotheses *Testing of final hypothesis before acceptance
Suggested format for the crime scene report
-introduction -characteristics of the scene -conditions of the scene -environmental conditions -factors pertinent to entry and exit -scene documentation -collection of physical evidence -search for latent prints -additional examinations
On scene examination of latent blood prints:
1. Amindo-black 2. leuco-crystal violet 3. fluorescein (alcohol-based not aqueous) *Never use luminol or aqueous based fluorescein in an attempt to develop latent prints *Wet surface-dry surface then apply techniques above
GSR residue contains trace amounts of 3 primary elements
1. Antimony 2. Barium 3. Lead
6 basic steps to crime scene processing:
1. Assessing 2. Observing 3. Documenting 4. Searching 5. Collecting 6. Analyzing
Three basic on scene fingerprinting techniques:
1. Basic powder techniques (standard and magnetic) 2. Superglue fuming 3. Small particle reagent *Also be experienced in recovering prints from human skin using the adding machine paper technique and in the use of crystal violet solutions on adhesive tape. Also the recongize methods of recovering latent prints at fire scenes
Class differences in human blood
1. Blood type 2. Variations in blood antigens p.29
the most common fire signs found in the fire scene?
1. Char patterns 2. smoke and soot patterns 3. Damage patterns
5 basic search patters:
1. Circle/Spiral 2. Strip/Line 3. Grid 4. Zone 5. Point to Point
Based on specificity, the characteristics presented by all physical evidence can be classified in two categories
1. Class Characteristics-allows the item to be compared with a group. Characteristics that are common to several objects. Best used in eliminating possibilities. i.e. size, color, common manufacturing pattern 2. Individual characteristics-allows the scientist to compare the item with a specific object/person and include/exclude it as originated from it. "unique" resulting from natural variation, damage, or wear. i.e. fingerprint
Steps in Event Analysis
1. Collect Data, Establish Likely events 2. Establish Event segments from the data available 3. Define Associated Event Segments 4. Order and Sequence the Associated Event Segments 5. Audit the Information 6. Determine and Final Order the Events 7. Flow Chart the Overall Incident Based on the Event and Event-Segment Sequence
What can be used to compare trace evidence to know samples
1. Comparison microscope 2. Infrared Spectrometry 3. Automated refractive index sustem 4. Scanning electron microscope
5 basic objectives to achieve the 2 basic police goals:
1. Crime Prevention 2. Crime Repression 3. Regulating non-criminal conduct 4. Provision of services 5. Protection of personal liberty
Variations of view for the crime scene sketch:
1. Cross-Projection or exploded sketch- combines the standard bird's eye view with "laying down" walls to depict evidence on vertical surfaces 2. Elevation sketch-side view of some portion of the scene, typically a wall or similar vertical structure 3. Three dimensional sketch or view p.166
On scene examination of adhesive surface:
1. Crystal violet, alcohol/water technique 2. Sticky side powders (wet surface allow to dry before trying any of the above-techniques)
On Scene examination of rough non porous surfaces:
1. Cyanoacrylate fuming 2. Powders (consider fluorescent for contrast)
On scene examination order for paper:
1. DFO 2. Ninhydrin 3. Silver Nitrate
It is imperative that narrative scene descriptions be:
1. Detailed, with all the pertinent facts and conditions documented 2. Accurate, with few inferences or subjective evaluations included 3. Understandable, i.e. logical and organized
Functional Photograph Method
1. Document the entire scene in situ 2. Photograph transient evidence as soon as possible 3. Document with mid-range and close-up photographs 4. If items are discovered later, document appropriately 5. Create photographs that document examination results 6. Maintain a photo log
Used to examine paint samples
1. Fluorescent microscopy 2. Infrared Spectrometry 3. Gas Chromatography 4. Scanning electron microscope
The composition of the crime scene team is defined by these two approaches:
1. Functional approach- the team leader designates different teams to do different activities (photos, latents, sketching) 2. Area approach- a single team handles all activities associated with processing p.98
Datum point can be set using
1. GPS device 2. Triangulation to evident landmarks in the area 3. By physical location using a metal pipe or rebar (worst case)
Chemical analysis is accomplished through what intrusmentation
1. Gas Chromatography 2. Mass Spectrometry 3. Infrared Specgtrometry
Basic subunits of genes
1. Guanine (G) 2. Crtosine (C) 3. Adenine (A) 4. Thymine (T) G always pairs with C, A always pairs with T
Types of trace evidence
1. Hair 2. Fibers 3. Glass 4. Paints 5. Soil
The formal sketch has 5 basic elements
1. Heading-informs viewer of the purpose 2. Diagram area-the drawing itself 3. Legend-what the labels depict 4. Title block-important info, DR, address, date/time, sketcher 5. Scale and Direction notation-compass direction and if there is a scale of reference used
Total station systems use what tree measurements from a know datum point?
1. Horizantal angle 2. Vertical angle 3. Slope distance
Three measurements used in Polar Coordinates
1. Horizontal angle-a rotation of the sighting instrument from north in the horizontal plane 2. Horizontal distance-is measured as the distance between the datum point and the evidence item 3. Difference in elevation (when recording elevation data)-elevation is measured as the difference in height from the datum point elevation and the evidence.
Recurring photographic problems:
1. Identification problems 2. Orientation problems 3. Confusion problems 4. Incomplete documentation
Ballistics is broken down into three areas of study:
1. Internal or interior ballistics 2. terminal ballistics 3. External or exterior ballistics
3 areas to consider regarding officer safety:
1. Is this a crime in progress and are there suspects on scene? 2. Are there natural hazards present that can inhibit or harm first responders? 3. Are there man-made hazards present that can endanger first responders?
Any good processing method will demand 5 basic ingredients:
1. Knowledge 2. Skills and Knowledge 3. A methodical approach 4. Flexibility 5. A coordinated effort
Improper photograph can be blamed on 2 main areas:
1. Lack of understanding or practice with photograph equipment 2. Lack of understanding of what the photographs are intended to depict p.132
Fingerprints can exist in 3 basic forms:
1. Latent Print 2. Patent Print 3. Plastic Print
3 basic ridge patterns
1. Loops 65% of all patterns 2. Whorls 30% of all patterns 3. Arches 5% of all patterns
To determine angle of impact:
1. Measure the long and short axis of the stain without the tail or scalloping 2. Divide the short axis by the long axis (should be less than 1) 3. Determine the inverse SIN of this number
Search method employed needs to be:
1. Methodical 2. Systematic
Factors to consider regarding the area or search swath that a single searcher is responsible for:
1. Nature of the ground being searched 2. Lighting conditions 3. On-scene environmental conditions 4. Size of the item being searched for
On scene examination of untreated wood:
1. Ninhydrin 2. Powder/brush
Documentation of the scene has 4 key elements:
1. Notes 2. Photographs/video 3. Sketches 4. Reports
Other than wet surfaces, SPR can be effective in what other situations?
1. Oily windows 2. Oxidized metals 3. Galvanized surfaces 4. Salt water sprayed areas
3 basic types of photographs
1. Overall 2. Evidence establishing 3. Evidence close-up
Two issies with the brush and powder techniques:
1. Overpowder a latent print 2. Applying too much pressure when dusting the print
Bloodstain patterns are grouped into two basic categories:
1. Passive stains 2. Dynamic patterns
Two primary field test for the presumptive presence of blood
1. Phenolphthalein 2. Leucomalachite green
In order to produce quality crime scene photographs the technician must control 3 basic aspects of the camera:
1. Physical control-stabalizing the camera when the shutter is released 2. Light- No matter what the light conditions a flash should be employed (fill flash) 3. Focus and Depth of Field- greater depth of field=smaller f-stops
Areas of specific consideration when searching for fingerprints...
1. Points of entry 2. Points of exit 3. Any appropriate surfaces in and around the area where the actual crime was committed
On scene examination of glossy surface paper:
1. Powder/brush 2. Cyanoacrylate
According to Rynearson & Chisum, context of evidence may manifest itself in a number of ways. Name the 5 ways:
1. Predictable effects 2. Unpredictable effects 3. Transitory effects 4. Relational details 5. Functional details
In deciding where to establish an initial perimeter the officer should consider the following:
1. Primary focal points 2. Natural entry and exits points 3. Secondary scenes
Most common mapping methods
1. Rectangular coordinates 2. Triangulation 3. Baseline coordinates 4. Polar coordinates 5. Triangulation or rectangular coordinates on a grid 6. Triangulation on a baseline 7. Total station systems
Debriefing the responding officers: Once the initial responding officer is found he should be interviewed to determine the following:
1. Scene Scope and nature 2. Changes to the scene (i.e. police/fire entry) 3. Status of parties involved 4. Scene Security
The purpose of a debriefing and assessment by the investigative team is to consider the following issues:
1. Scope of the scene 2. Scene integrity and contamination control 3. Team approach and composition 4. Search methods to be used 5. Personal protective measures
When a smooth non porous surface is wet:
1. Seize and dry followed by the usual techniques OR 2. Small particle reagent
When a porous surface is wet:
1. Seize and dry-follow by physical developer
Other processes that may work on non porous smooth surfaces:
1. Silver nitrate may work on some plastics 2. Iodine fuming may be effective on fresh prints other than those located on metal
3 categories of tool marks
1. Striation 2. Compression 3. Saw and drill marks Striation marks are caused by the cutting edge of a tool in contact with/sliding against a target surface. Compression mark is when a tool is forced into a soft material.
Sighting instruments used in Polar Coordinates
1. Surveyor's Transit 2.Laser sighting device 3. Handheld compass (in a worst case)
Two basic goals of police
1. The prevention of crime and disorder and the preservation of peace. 2. The protection of life, property, and personal liberty.
Subdivisions within fingerprint patterns
1. Ulnar, radial, and double loops 2. Plain, central pocket, and accidental whorls 3. Plain and tented arches
When considering each item observed in the scene, the investigator should ask 3 questions:
1. What is it and what function and what function did it serve? 2. What relationship does it have to any other items of evidence or to the scene itself? 3. What does it tell us about time and sequencing aspects?
On scene examination of human skin (alive):
1. adding machine paper technique
On scene examination of human skin (dead):
1. adding machine paper technique 2. cyanoacrylate fuming 3. magnetic powder 4. iodine fuming
3 basic scene integrity concerns:
1. addition of material to the scene. 2. Destruction of material in the scene 3. Movement of material in the scene
On scene examination of all non porous smooth surfaces:
1. cyanoacrylate fuming 2. powders (consider fluorescent for contrast) 3. Small particle reagent
Fire requires what to exsist?
1. heat 2. fuel 3. oxygen 4. uninhibited chemical chain reaction between the three *Known as the fire tetrahedron
The disipline of bloodstain pattern analysis considers...
1. location 2. shape 3. size 4. distribution 5. other physical characteristics of bloodstains
Primary methods for enhancing latent or slightly visible bloodstains
1. luminol 2. fluorescein 3. amido-black 4. leuco-crystal violet (LCV)
On scene examination of visible bloody prints:
1. photograph and lift or enhance with powder 2. Amido-black 3. Leuco-crystal violet
Scene conditions at fire scenes...
1. the fire damage itself 2. the resulting creation of unstable structures, 3. the presence of significant debris covering evidence 4. the fact that burned surfaces are black and do not reflect light effectively
Phenolphthalein consists of what three basic solutions
1. the phenolphthalein solution itself 2. ethanol 3. hydrogen peroxide as an oxidizer
Reference Scene Integrity: 3 techniques for handling supervisors or politicians are:
1. to enforce the use of standard personal protective measures 2. to enforce the use of scene entry log 3. to consider creating walking routes or observations points for authorized visitors
Stock solution of crystal violet:
1.5 grams of crystal violet powder in 100 ml of ethyl alcohol.
Ridge identification is based on at least 15 different ridge characteristics
1.ridge endings 2.bifurcations 3.short ridges 4.enclosures 5.ridge dot 6.ridge break 7.angular formations (deltas) 8.overlap 9.spurs 10.bridges 11.trifurcations 12.crossings 13.change overs 14.ridge pinch 15.loops
Long elliptical bloodstains indicate an impact angle of
10-30 degrees
When luminol is prepared from bulk the mixture is
100ml of distilled water, 0.1g of luminol, 0.7g of sodium perborate, and 0.5g of sodium carbonate
At what temperature does flash over occur?
1100 degrees F
Heat energy and thermal imaging wavelength?
12,000nm
Shortwave UV wavelength
180-254nm
Fill dirt is removed from gravesites in what size layers?
2 inch layers across the entire surface until a stratum or artifact is located.
Working solution of crystal violet
2ml of stock solution per 100 ml of water
Longwave UV wavelength
365-415nm
Crime scene search filters employ a broad passband filter encompassing _ nm?
390-520nm
Visible light spectrum in nanometers
400nm (violet)-700nm (red)
Near UV and Violet wavelength
415nm-485nm
Blue light wavelength
485nm-530nm
Orange-Red wavelength
570nm-700nm
Infrared wavelength
700nm-2000nm
Fingerprints consist of:
98% water and 2% a combination of grease, oils, salts, and amino acids
Identify sperm/seamen by testing for:
Acid phosphatase
Lifting of prints on rough non porous surface:
After powdering use a silicone based casting material, textured surface lifting tape, or textured surface lifting material
Evidence
Anything that tends to prove or disprove a fact in contention. p. 7
In situ
As found
Total station mapping
Automated surveying systems that use methods very similar to polar coordinates. A total station combines automated transits, lasers, and computer technology.
Barrier Filter
Barrier filter keeps the orginal wavelength from passing, but allows fluorescence energy to pass and be seen
At 455nm?
Biological fluids are easily observed in combination with an orange barrier filter
Name of latent processing technique that provided the idea to process fire scenes with a more critical eye...
Camphor technique.
Taxonomy of stains
Classification of stains
Most import tool the Crim Scene Technician uses in any crime scene?
Clean white light
Crime Scene Sketch
Could be anything from a freehand drawing to a computer generated to-scale document
Excitation Filter
Creates specific wavelength
Reflected light
Defines the color of the object we visulize. The object absorbs all colors except the one we visulize, ie blood absorbs all colors except for red.
DNA
Deoxyribonucleic acid Existence first reported in 1868 Structure discovered by Watson & Crick in the 50's
A clandestine gravesite may exhibit what appearances?
Disturbed soil, a grave mound, or even soil compaction. Vegetation around the immediate grave is likely to have been disturbed by the activity therefore it may be absent or in a state of regrowth that is dissimilar to the surrounding vegetation.
How do u test for copper in a defect?
Dithio oximide. 10% ammonia on the filter paper applied to the defect. Then spray with DTO. Positive test then it will turn green
On scene examination of wet rought non porous surfaces:
Dry, followed by powder and brush technique
Indented writings are most often recovered using what instrument
Electrostatic detection apparatus (ESDA)
ESLD
Electrostatic lifting devices
Fire patters do what?
Fire patterns show the progress of the fire, demonstrate the nature of the fuels involved and help to locate and isolate the actual origin of the fire. Visible and meaurable physical effects on the material in the scene.
"Fixing" the evidence
Fixing the evidence allows the investigator to functionally place the item back in the scene with some level of accuracy. p.171
3-4-5 rule
From a point three units from the grid corner on one axis, to a point four units from the same corner on the adjacent axis, the distance between the two points is five units.
Triangulation or rectangular coordinates on a grid
Grids are effective for large scale scenes where multiple teams are mapping with. I significant landmarks or in small scale scenes such as gravesites.A grid is created using stakes which become the landmarks.
Report-Search for latent fingerprints
Identify where fingerprinting was attempted, where it succeeded, and the nature of prints recovered (partial latent prints, palm prints, footprints)
Report-Collection of physical evidence
If the organization does not use an evidence log then a describtion of what was seized and where it was found.
Primary goal of forensics
Individualization, the examination of individual characteristics. p.25
Report-Conditions of the scene
Intended to identify the specific conditions that are pertinent to the investigation. i.e. cleanliness, level of disarray, describtions of items of evidence, odors etc.
Report-Characteristics of the scene
Intended to provide a general description of the scene and associated features of the seen such as doors, windows, openings, and geographical features in an outdoor scene. Furniture, appliances etc, present day to day are deceived in some detail as well.
Report-Factors pertinant to entry and exit
Intsded to deal with both known and possible avenues of approach and departure from the scene.
Report-Scene documentation
Is intended to describe the basic efforts taken to photograph and sketch the scene.
Reference basic scene integrity concerns: Golden Rule is?
Know who did what. P.17
At 485nm?
Latent prints developed in ninhydrin and be visualized using a yellow barrier filter
UVA
Longwavve UV
Fluorescence
Luminescence that happens as long as the object is exposed to an active energy source (ie ALS)
What types of nonintrusive technologies can be used to help locate a gravesite?
Magnetometers, ground penetrating radar, and infrared thermography; also a trained cadaver dog
Mitochondrial DNA analysis (mDNA)
Mitochondria are organelles in each cell where the production of Adenosine triphosphate (ATP) occurs. It is inherited only from the mother. It is gaining popularity in hair analysis.
SPR consists of...
Molybdenum disulfide suspended in water solution.
Basic Scene Integrity Concerns: Movement of Material
Movement is often the result of investigative processing techniques, but when such movement is unchecked and unrecognized it clouds the investigators understand of the crime scene. Movement of material significantly changes the relation aspects observed. i.e. moving the weapon from the hand of susp. P.16
Muzzle ranges: Close contact or hard contact
Muzzle is in direct contact with the skin or pressed into the skin
Triangulation on a baseline
On exterior scenes where evidence is not too widely scattered but where there are no adequate landmarks then a combination or baseline and triangulation can be applied. Reference points are marked on the baseline and evidence is triangulated using the reference points.
Report-additional examinations
Open to describing any additional evaluations or examinations.
ESLD works on what concept?
Opposites attract
What method drives every fire investigation?
Origin and cause
More about physical evidence power
Physical evidence has a greater power and ability than testimonial evidence in defining what happened at any crime. Physical evidence is what it is and it is tangible. p. 23
2nd developed technique for DNA testing
Polymerase Chain Reaction (PCR) Allowed the scientist to copy the DNA structure in small samples that would have been too small for RFLP technique. The statistical discrimination by PCR was significantly lower than RFLP.
5 basic objectives applied: Crime Prevention
Prevention includes actions and efforts designed to keep crime from occurring in the first place. i.e. community programs, youth programs, proactive patrol techniques, neighborhood watch. p.2
When using orange-red wavelengths us what barrier filter?
Red barrier filter
RUVIS
Reflected ultraviolet imaging system
Report-Environmental conditions
Reports on any weather or scene conditions noted at the time of the investigation.
Basic Scene Integrity Concerns: Addition of Material
Results in post incident artifacts. In effect the authorities end up creating evidence that was not there to begin with. Often used by defense to cast doubt or support alternating theory. p. 16
Basic Scene Integrity Concerns: Destruction of Material
Results in the loss of an item's evidentiary value. i.e. trampled dew trail, placing body in body bag causing loss of blood patters on clothing etc. p. 16
Method of evaluation of direction of force: 4R Rule
Ridge lines on Radial fractures are at Right angles to the Rear
450nm is good for?
Searching for/visualizing bite marks/bruises on human skin when used with a yellow barrier filter
3rd Major break through in DNA testing
Short tandem repeat (STR) Combined concepts of PCR but had statistical discrimination higher than RFLP. Ability to evaluate such small samples is significant but creates great risk for cross contamination.
UVB/C
Short wave UV
Define SPR
Small particle reagent
What can blood spatter analysis provide the investigator?
Specific information relating to where the associated event occured, what items were involved in the event, and the relative position of people and objects at the time of the event.
Physical Evidence
Takes the form of specific items found at the scene that are often collected for subsequent analysis and presentation. Sometimes it is not "collected" but documented through photograph/sketching. p.7
Crime Scene Mapping
The "process" of taking and documenting measurements of items present in the scene
What happens to blood stains when exposed to longwave UV?
The bloodstain absorbs all the light of that bandwidth, reflecting nothing back, thus will appear black
What four basic ways can light energy act on an object?
The energy will be reflected, absorbed, transmitted, or converted (or any combination of the four)
Evidence establishing photograph
The evidence establishing photograph are taken in such a fashion that the item is framed in conjunction with some other obvious landmark evident in the overall photograph.
Release of energy
The excited electrons fall back to normal energy state, releasing energy as light. This release is at a lower energy state than the original light.
Phosphorescense
The object continues to give off light in the converted wavelength even after removal of the energy source.
Overall photograph
The purpose of an overall photograph is to depict the general condition and layout of the scene. p.135
What happens to biological stains when exposed to longwave UV?
The will fluoresce with a lime green color even without a barrier filter
False positive reaction differences in luminol
There is a differenct in color, duration, and intensity. Flase positives usually is an immediate and intense reaction (almost a flash of light) that dies out quickly. Color is more light green/white. Toliets can present long duration blue violet color response
Evidence close-ups
They are close-up photos. The technician should try to fill the frame with the item of interest.
Report-Introduction
To identify who worked the scene examination, where the scene was, the time/date of examination, and a short explanation regarding the reason for examination.
Basic goals of incident management by a first responder can be achieved and expressed in 5 objectives:
To safely an effectively gain control of the scene the initial responding officer must: 1. Document the provided information 2. Not become a casualty 3. Provide for emergency care 4. Secure and control the scene and all those within it 5. Release the scene to the appropriate authorities (Dets or CSS) p.60
Define Truth:
Truth is defined by the collection of evidence, factual information that allows us to draw some conclusion about an event. The CSI realizes the significance of physical evidence in defining this truth. Unlike testimonial evidence, physical evidence does not lie. P.20
How is the presence of metallic lead in a suspected defect evaluated?
Using a sodium rhodizonate test
On scene examination of wet human skin:
Utilize the adding machine paper technique which is not negatively impacted by moisture.
455-485nm can be used to?
Visualize fluorescein reactions with latent blood. Typically using a yellow filter but an orange filter can be effective too when using the higher wavelengths
5 basic objectives applied: Crime Repression
When prevention fails, the police then seek to repress the criminal by actively investigating crimes and attempting to identify those responsible. Once identified the police are responsible for apprehending the criminals and bringing them to justice.
When should the reaction be halted in superglue fuming?
When the test print first begins to appear.
The color white represents...
a reflection of all wavelengths
The color black is...
an absorbtion of all wavelengths
Crime Scene Processing consists of:
an examination and evaluation of the scene for the purpose of recovering physical evidence and documenting the scene's condition in situ (as found). p. 1
Drip patterns occur when...
an object dripping blood is stationary for a period of time.
the presumptive tests are based on...
an oxidation-reduction reaction of chemicals that occurs in the presence of heme, a component of hemoglobin
Impact angle
approximate angle at which a droplet struck a surface
Unpredictable effects
are changes that occur in an unexpected or random fashion. i.e. found in the entry of police or EMS into a crime scene. often open doors/turned on lights then fail to report it. moving of evidence or haphazard opening of a revolver. p. 10
Dynamic patterns
are created by foreceful events, where fluid blood is projected out from a source under some force or compression. ie spatter, castoff patterns, arterial patterns, splashes, and spines
Patent Prints
are fingerprints caused by the deposit of contaminants such as bloody or greasy finger marks
Forensic firearms examiners
are the people who deal with internal ballistics. This includes the study and examination of the firearm itself, which includes ejection patterns, gunshot residue deposition, and other related aspects.
Fire patterns
are the predictable behaviors of fire that leave both blatant and subtle effects.
Bear claw shaped bloodstains indicate an impact angle of
between 40 and 60 degrees
circular bloodstains indicate an impact angle of
between 70 and 90 degrees
Rubberized casting compounds are not effected for recovering...
bite marks from human skin or for casting dirt impressions.
Saturation stains occur when...
blood is drawn into clothing, cloth, or pereable items. Often mar or destroy other blood patterns of interest
Contact stains occur when...
blood is transferred from one object to another through some form of contact ie. pattern transfers, wipes, swipes, and saturation stains
Directionality of a bloodstain is defined by
both the long axis of the stain and the presence of scallops, tails, and satellite spatter.
Responding officers objectives at a crime scene:
bring the site under control and coordinate resources. p. 59
Point of convergence
by visualizing a line aligned with the direction angle and extended back into the scene (reverse vectors) for a number of related spatters, a point of convergence will form where the lines cross each other on a surface
Damage patterns
can be evident on a single object or extended across an entire room. As an object is subjected to flame and heat from the fire, the exposed surfaces are damaged.
Luminol can have false positives from what items
certain metals, vegetable peroxidase, and cleaning cemicals
Predictable effects
changes to a scene that occur with some rhythm or regularity. i.e. Forensic entomology, rigor/livor mortis follows a somewhat predictable timeline. p.10
Investigators role in repressing crime:
conducting objective investigations in an effort to define who did what and why. P.18
Terminal ballistics
considered by the forensic pathologist, the effect of projectiles on the body
External ballistics
considers the trajectory of the bullet after leaving the weapon. The information derived is dependent upon the scene and the targets incolved.
"events" in event analysis
define gross aspects of the incident, such as approaching the scene, controlling the victims, killing the victims, etc
Luminol is a combination of
distilled water, luminol, sodium perborate, and sodium carbonate
Flurescein solution is
distilled water, sodium hydroxide, fluorescein, and zinc. 25ml of disilled water with 0.25g of fluorescein and 0.5g of zinc
Polar Coordinates
effective technique for mapping exterior scenes where the evidence is significantly scattered over an open area. Not suited to situations where line of sight is limited by woods/other obstacles. Based on a surveying technique. Using sighting device, measure two to three basic measurements from known point of the evidence.
Alternative light sources (ALSs) allow the crime scene technician to...
employ a variety of narrow wavelengths of the light spectrum in an effort to identify, visualize, and document a variety of different types of physical evidence.
Locard's Priciple of Exchange
every contact leaves a trace. p.25
Plastic Prints
fingerprint impressions where a print has been deposited in a soft surface such as wax p.27
Typical pattern transfers include...
hand or foodprints and patterns of bloodied knife blades or blunt force weapons
Rubberized casting compounds are most effective when used on...
hard substrates such as metals, wood, bone, or plastic.
Special condition surfaces:
human skin, adhesive tapes, and blood prints
At 525-530nm?
in combination with an orange barrier filter are excellent for developing and visualizing latent fingerprints with fluorescent powders
Latent Prints
invisible prints created by the deposit of normal body secretions.
Rectangular coordinate method
is best suited for crime scenes with clear and specific boundaries (e.g., interior walls). It is a fast and effective method. The technician fixes the evidence by measuring at right angles from the evidence to the surrounding walls and surfaces. Generally only two measurements from the center of mass to document each item. Thus less precise than other techniques and it does not "fix" the evidence since it can be rotated in that position.
Baseline Coordinates
is best suited for exterior scenes without evident landmarks. Begins with a datum point-a location from which the baseline will extend. It is set by triangulating it to a set of nearby landmarks. Once datum is set a baseline is extended across a cardinal direction (N, S, E, W) as far as necessary. Best to use actual tape measure but can use line or string, with ref points marked on the line. Then measure items at a right angles to the baseline then the distance along the baseline to the datum point.
Testimonial Evidence
is collected through the interview and interrogation of witnesses. Major flaw: it is offered by humans and humans are subjective creatures. p.7
Cross contamination
is directly associated with Locard's Principle of Exchange and caused by inappropriate handling of evidence. p. 25
Triangulation method
is effective for fixing evidence. Rules are based on whether an item has a regular or irregular shape. Items with a regular shape-will not change with movement, contain specific identifiable points-are fixed with a min of 4 straight-line measurements from two landmarks in room to two points on article. (i.e. furniture, guns, knives). Irregular shape items-items that will change shape when moved-documented with two measurements from the center mass to two distinct landmarks and a measurement of overall width of item. (i.e. blood pools, clothing, circular drink glass upright). Regular shaped items-2 "triangles" (4 measurements) Irregularly shaped objects- 1"triangle" (2 measurements)
Most basic consideration of light
is ensuring the presence of light of sifficient illumination on scene in order to conduct a thorough search.
Absolute chronology
is related to timing aspects.
The "incident" in event analysis
is the overall situation being investigated
Relative chronology
is the seuencing of event segments in relation to one another. Relative chronology is thetrue back bone of the reconstruction. No association with absolute time.
Area of origin
is the three dimensional space above the convergence point
Sodium rhodizonate test consists of what?
it requires 3 working solutions. 10-15% solution of glacial acetic acid. then a working solution of sodium rhodizonate (4g to 100ml of water), which should turn scarlet if lead is present. then 5% hydrochloric acid which should turn the scarlet to blue violet
Transmission of light relates to
its penetrating power;light energy can pass through and object
Conversion of light
light energy can be converted from one wavelength to another, creating the condition known as luminescence.
Thermal imaging has been used effectively to...
locate decomposing bodies and to find hot spots in fire scenes. Also available in a handheld device to distinguish between recent and older tire marks on accident scenes.
Relational Details
maifest themselves through the investigators ability to physically place items in the scene. i.e. void in spatter, clustering of shell casings able to establish a correlation between various objects. p. 11
Functional Details
manifests themselves in the operating condition of items in the scene. i.e. is the weapon capable of operating normally? p.11
"event segments" in event analysis
microcomponents of the event. sevent segments are snapshots of specific moments in time, detailing specific actions that occurred. Event segments are always defined by specific data.
Muzzle ranges: Intermediate range
muzzle is between 5-40 inches. intermediate range gunshot wounds are deduced from the presence of stippling around the wound. Different types of powders travel and embed at different distances, resulting in an ability to define the wound as intermediate
Muzzle ranges: Loose contact
muzzle is in extremely close proximity to the skin but at the moment of firing a gap is created between the two
Muzzle ranges: Near contact
muzzle is not more than 5 inches from the skin
Critical consideration in superglue fuming is...
not to overfume the latent print.
Fly spot
occur as the result of fly activity in a scene. The movement of flies can track blood from a body or blood source and deposit it on surrounding walls and surfaces. Flies also regurgitatae blood onto these surfaces.
Swipe pattern
occur when a bloody object makes contact through some for of lateral motion with an unstain object
Wipe patterns
occur when a prexisting stain is disturbed by another object
Void patterns
occur when a secondary object is present between a bloodstain event and a nearby surface. Voids appear most often in spatter events
Splash patterns
occur when a volume of blood is projected into the scene with minimal force
Cast off patterns
occur when an object is bloodied and then moved or swung with some force.
Transitory effects
oftentimes they are fleeting. Ultimately, time and environment will destroy any transitory effects. i.e. heat of a burning cigarette, presence of ice in a glass, odors of chemicals or colognes. p.11
Porous surface examples:
paper, cardboard, untreated wood
Soil Sample Collection
place in a small, clean, pint-sized, paint cain. Generally 1/2 to 1 cup of material is suggested for any analysis.
Crime scene entry control log is intended to:
provide a running record of everyone who entered the scene, when they entered, why they entered, and what time they left. p.98
Infrared wavelengths are most often employed in...
questioned document examinations. Has little direct application to crime scene processing.
Passive Stains
result from an action other than a directed force to a blood mass ie. contact patterns, blood clots, drip patterns, drip trails, and blood pools or flows
Arterial patterns
result from blood in volume that is projected into a scene under pressure from an artery or heart
Smoke and soot patterns
result from the outflow of fire products
First break through in DNA testing
technique known as Restrictive Fragment Length Polymorphism (FELP) discovered in 1984 by Alec Jefferys relied on large and undegraded samples
Identify the presence of saliva by:
testing for the presence of amylase or starches.
Directionality of the stain
the direction the droplets were traveling at the moment they struck a surface
Stippling or tattooing is
the embedding of unburned and partially burned gun powder residues in the skin
SPR reacts with what in a latent print?
the fats found in the latent print
Interpretive value of evidence
the full meaning of evidence is a function of time and the items surroundings (Rynerson & Chisum) In other words its an issue of context than mere content. P.8
All radiant energy is measured by...
the length of its wave (from peak to peak), wavelengths are measured in nanometers
Refractive Index (RI)
the manner in which it allows light to pass through it
Consdieration is also given to...
the nature of the object and how one would typically touch or manipulate the item.
The basis of all crime scene reconstruction is...
the scientific method
Intrusive techniques for locating a grave are...
the use of probes and vapor monitors. Vapor monitors are used to detect decomposition gases
Muzzle ranges: Indeterminate range:
this determination means that no conclusion can be drawn on muzzle distance. This determination is found in situations where there are no markings except for the bullet defect
How is fluorescein reaction seen
using an ALS set between 455-485nm with a yellow barrier filter. orange will also work
Char patterns
usually result from direct flame involvement
Nonporous smooth surfaces:
varnished and painted surfaces, plastic surfaces, glass
Orange and red wavelengths are effective for...
viewing inks on items present in the scene as well as questioned documents. May also assist in visualizing subcutaneous bruising.
Nonporous rough surfaces:
vinyl, leather, textured countertops, and other textured surfaces
Pyrolysis
when heat breaks down the fuel source into gas and vapors that burn
Expiratory spatter
where there is blood present in the airway and exhalation of the victim will break the blood into small droplets, which are forced out of the airway