Impression Evidence Exam 2
Should you use a fingerprint roller with gelatin lifts?
- No
can you reuse lifting film?
- No
Two-Dimensional Footwear Impressions:
- can be composed of any materials from blood to mud to oil to dust -Can be very heavy or very light - Can contrast very well with substrate or be very faint so as not to be seen
Gelatin lifters
- can be used with ESL fails -Black gel contrasts well with light dust impressions
Wet origin impressions:
- clean shoe outsole is wet or damp or the receiving substrate is wet or damp -most are dry before they are observed; must still be evaluated as wet origin impressions -often difficult to see and photograph - can sometimes be enhanced with fingerprint powder -must then be photographed; a contrasting color gelatin or adhesive lifter can then be utilized to recover the impression
Diaminobenzidine
- colorless reagent which reacts with hemoglobin derivatives to produce a dark brown insoluble residue in the presence of hydrogen peroxide - dark brown color with digital imaging techniques to remove background colors -must be freshly prepared
Factors affecting choice of enhancement techniques:
- composition and consequent limitations of the surface material -texture and porosity of the surface - condition of the surface - composition of the impression - wet or dry origin impression - humidity - location of application - logistics involved in and the availability of the technique
Excess dust can be carefully cleaned from both impressions and lifts utilizing:
- compressed air -not possible with negative dust lifts
Use of digital enhancements
- computer and graphic arts software
White gelatin lifts work well with:
- dark originals - black or fluorescent fingerprint powders -chemically treated impressions when procedure is focused on fluorescent photography - dropping complex background coloration or patterns
Factors affecting the quality and detail of footwear patterns on bodies
- depth and detail of shoe design -degree and speed of impact - angle of the shoe relative to the skin - clothing interference -victim's movement at the time of impact
Brannock device
- designed to indicate the shoe size while also including a built-in additional 1/2 to 3/4 inches of room within the shoe for the space between the longest toe and inner tip of shoe
Numerous formulations exist for this purpose and are the same or similar to those used in fingerprinting:
- detect trace materials or metal ions - stain or react with blood components
Positive controls:
- determine if the chemicals are working
Oblique light
- directed across the impression at a low angle of incidence -side lighting -2D impressions require that the light enter at a very low angle -the deeper the 3D impression, the higher the light will need to be positions
Applications of the ESL
- dry origin can be lifted from virtually any surface -best on dry dust or dry residue footwear impressions -wetness creates a stronger bond between impression and substrate and ELS will not work -Impression wont be damaged by failed ESL -Too much dirt on a surface may make it difficult to get good lift (too much will lift) -negative impression may be lifted -must use the device routinely to become and stay proficient with its use
Wet origin
- either the shoe and/or the receiving surface is wet or damp when impression is made
Detecting indentations
- electrostatic detection apparatus - indentation materializer
Physically transferring the impression from one surface to another:
- electrostatic lifting - gelatin lifting - adhesive lifting
Bluestar
- emits intense blue-white chemiluminescence in range of 420-440 nanometers -total darkness is not required -doesn't alter DNA
Why is amido black commonly used
- familiarity -low cost - contrast potential
Potassium Thiocyanate
- first reported in 1963 Japan - reacts with iron in soil
Application of protein stains
- fixing the impression -staining the impression -destaining the impression
Gelatin lifter uses:
- for both original and powder impressions - very versatile - generally better than adhesive lifters
Specialized Lighting and forensic photographic methods:
- high contrast photography and the use of filters -oblique light - cross polarization -ultraviolet light - infrared light - alternate light sources - high contrast photography and the use of filters
Dynamic loaded:
- high impact of shoe with victim - skin injuries in dynamic loading result from impact with velocities varying from low to high - high velocity blunt force trauma may lead to injuries with a pattern or imprint - the object causing the injury, mostly bruising, is mirrored by the pattern - the impact caused by the blow with the object will distort and crush the skin and underlying tissues and rupture subcutaneous vessels in contact with the edges of the object
Questions often asked of a forensic shoe examiner:
- how do you determine what size shoe a person wears - can the accused wear a particular shoe size - can you determine what size shoe made the crime scene impression
Crime scenes for bloody impressions:
- if full capabilities for enhancement are not available, secure the scene until assistance is available - recover bloody items of evidence for enhancement in the lab -when cutting materials containing visible bloody impressions, make sure not to miss latent blood impressions
Photographs can potentially visualize:
- impressions better than viewing them on lifting film
Oblique lighting routinely used to photograph:
- impressions in soft substrates - on electrostatic lifting film - in combination with other techniques
Chemical reagents and methods for enhancing bloody impressions:
- impressions made in victims blood are very important to a case - 6 to 10 impressions can be left by the amount of blood typically held on a shoe or naked foot
Amount of degradation of gelatin lifters is affected by:
- interaction between the lifted material and the gelatin -the substrate -whether a cover sheet was reapplied
Brannock device:
- invented in 1927
Factors to consider before lifting:
- is the substrate porous or nonporous
Problems encountered when trying to life two-dimensinal footwear impressions at the scene:
- lack of appropriate lifting material - lack of education/knowledge concerning what will lift certain types 2-D impressions
Bromophenol Blue
- lift muddy or dusty prints with low tack adhesive lifters in the field and later treat them with Bromophenol Blue in the lab -reacts with Calcium Carbonate causing impression to turn blue with humidity -turns yellow in drier climates
Gelatin Lifting vs ESL when searching large areas:
- long strips of ESL film is such is much more practical and successful
Negative controls:
- make sure the substrates are not reacting
More than one sizing system is utilized on:
- many shoe boxes and shoe size labels
Ritz Stick
- measures heel to toe length
Hungarian Red
- modified version of Acid Fuchsin produced in 1996
Mismatched feet
- most people's right and left foot dimensions are not the same - due to this, a possibility exists that a single perpetrator could leave impressions at a scene
Considerations for working with chemical enhancements:
- must use positive and negative controls - photography must be utilized during every step
Lifts provide a
- natural size recovery of the impression from the substrate, without any focus, scale, or perspective problems that may occur with photography
Can you determine shoe size based on Only Heel-to-Toe measurements?
- no
Gelatin Lifting vs ESL for dry impressions:
- no simple answer - because of their tackiness, gelatin lifters have a better likelihood of lifting more of the impression than ESL -GL is often better for lifting visible footwear; particularly when they are faint - for heavier dry impressions: make initial lift with ESL and then apply GL
Can you calculate the height of the perpetrator based on the dimensions of the crime scene impressions?
- no, not with sufficient accuracy to be reliable
Ninhydrin:
- not an enhancement process utilized at crime scenes - reacts with amino acids in perspiration
Adhesive lifters:
- not recommended for original impressions - used primarily for impressions developed with fingerprint powders on non-porous surfaces
Degradation of impressions with Gelatin Lifters:
- original impressions lifted w/ gelatin lifters can fade and degrade over time -Recovering gelatin with a cover sheet accelerates degradation -always remain uncovered until photographed -examination quality photos of original impression ASAP -Gelatin lifts of powdered lifts have shown no loss of detail as long as they are not covered
Physical methods of Enhancement:
- physically transferring the impression from one surface to another - use of fingerprint powder -detecting indentations
Electrostatic Lifting Film
- polyester film (mylar)
Two types of negative impressions
- positive - negative
Luminol
- possibly oldest chemical for detecting blood -created by Schmitz in 1902 -produces light - must be done in total darkness -highly sensitive -must be mixed right before use -use precautions when spraying -water based -must use fixative first -light sprays
Chemical methods for Non-blood
- potassium thiocyanate - physical developer - bromophenol blue
Until the late 1800s, a shoemaker would hand-last shoes meaning:
- process involving stretching and tacking the upper of the shoe over a wooden foot form ( the last)
Peroxide Reagents
- react with the heme group in hemoglobin -colorless dyes that yield color or light - leuco crystal violet - leuco malacite green - diaminobenzidine -tetramethylbensidine -fluorescein -luminol
Leuco Crystal Violet
- reduced colorless form of crystal violet -popular at crime scenes - research has shown LVC can provide excellent results for visualizing bloody impressions at a crime scene -These recovered impressions can then be collected and treated with more sensitive reagents such as Hungarian Red or Acid Yellow 7 - tends to photoionize or degrade when not thoroughly rinsed
Cobblers
- repaired shoes
Lasts:
- reproduction of the approximate shape of a human foot over which is produced a shoe
Which two innovations resulted in lower costs and hundreds of shoe factories?
- rubber soles - sewing machine
Issues with photographing blunt force trauma:
- scale - perspective - tissue variation - body movement
Mikrosil:
- silicone based product - good for lifting powdered impressions
Edwin B Simpson:
- sizing system adopted by the American and British footwear industries around 1888 -Also introduced half sizes (1/6th inch) and shoe widths (1/4th inch) - Adopted by both American and British footwear industries in 1888
Replication Limitations and accuracy
- skin is not the best medium to record detail - photographing this type of evidence can be challenging and problematic due to the topography of the skin -can be obscured by hair or clothing
Women's size will always be:
- slightly more than one size number greater than men's size for the same foot length
Alternate light source and lasers:
- sold by numerous manufacturers -controlled high intensity light source with various wavelengths of light -utilize goggles and filters -impressions can be viewed and photographed in the visible and UV range - can also aid in searching for impressions
Always use photography and other nondestructive techniques such as:
- specialized lighting and ESL first
Acid fuchsin
- stains blood protein components a deep magenta red
Amido Black
- stains proteins a dark blue-black -best on nonporous -2 g AB in 100 ml glacial acetic acid for rinsing -Do not use methanol based AB at crime scene - most commonly used for blood enhancements
Static loaded
- standing on a victim - injuries by low velocity impact loading usually do not show recognizable patterns of shapes
Factors affecting choice of enhancement technique when working with porous substrates:
- texture, porosity, or absorbability of substrate - condition of the substrate - color of substrate - composition of the impression - application location
Although there is correlation between physical size of a shoe sole, the impression it leaves, and the manufacturers shoe size:
- that correlation is not particularly useful when taking a shoe impression and attempting to predict a specific shoe size
Negative impression:
- the contact area of a shoe removes residue from a surface leaving a visual reflection of the areas of the sole where the shoe did not impact
To a forensic expert, size and shoe size refer to:
- the outsole and its components as they consider if it is or is not capable of having produced the same dimensional features present in a crime scene impression
Finding such patterns on the skin surfaces demonstrates that:
- the perpetrator did not simply stand on or make incidental contact with the victim, but had to direct deliberate and consider force against the victim in order to produce those injuries
To a nonexpert, size and shoe size mean:
- the same and refer to the manufacturers designation one the shoe or shoebox
The forensic examination of blunt force footwear pattern injury with known footwear requires:
- the same knowledge, training, and procedures used in any other footwear comparison
Specialized light:
- the use of various forms of light to assist with the visualization and photography of the impression
Enhancement is necessary to find:
- these impressions and increase the level of detail
If substrate is porous:
- to what degree and how much has the impression penetrated? - is it also absorbent? - is the substrate clean or is it dirty and likely to interfere with a lift? - is the impression of wet or dry origin? - is the composition of the transferred material blood, mud, grease, dirt, dry dust or residue or unknown? -is the impression very thin and barely visible? are there other methods of enhancement? - is there a sequence of lifting and/or enhancement methods to be considered that would provide a greater chance of success?
-violent kicking and stomping may result in patterns from other areas of the shoe such as:
- toe - lace - heel
Visible impression on moveable items should be:
- transferred to the crime lab "as is" - only be lifted at the scene when the items they are in cannot be removed and submitted to the laboratory
Physical Developer
- used after ninhydrin -best on items previously wet or subjected to high humidity
Adhesive Lifters:
- used historically more in the US than any other method - often results in poor results and poor contrast -not recommended for lifting original or powdered impressions -can be used in emergency situations
Iodine Fuming:
- used in fingerprinting - reacts with grease or fat content of the prints; similar materials can also make footwear impressions -Can be useful in enhancement of wet origin footwear impressions -not good on dry residue or dust impressions
High contrast photography:
- using lighting and filters to increase the contrast between the impressions and the substrate
Different shoes of the same shoe size will:
- vary in the physical shape and size of both their inner dimensions and outsoles dimensions
Gelatin lifts made of mixture of:
- water-based gelatin -dyes - anti-fungal agents - proprietary materials on top of a linen-reinforced natural rubber backing -lifting side is protected with a clear cover sheet which must be removed before use
Cyanoacrylate Ester Fuming:
- well known for fingerprinting - some success when used for footwear impressions -excellent results with wet origin impressions on most nonporous substrate - white prints appear in few hours - using cyanoacrylate fuming on bloody impressions will prevent any further enhancement potentials
Determining which chemical to use
- what are the substrates porosity, color, texture - can the reagent be used on small or large area -what are the capabilities, resources, and experience of the CSI
Positive impression
- when a shoe deposits material onto a substrate -residue visually reflects the areas of the show that impacted the substrate -most common
Acid Yellow 7
- works well on nonporous substrates -not recommended on highly absorbent substrates
Make a quick:
-"snapshot" photograph for investigative purposes
July, 1970
-Kato Masao -dust on high voltage parts of TV -developed a static electricity machine -14,000 volts and had an electrode plate and black vinyl sheet -first ESL
Moderate force with fingerprint rollers should NOT:
-be used when applying the lifter
Always take examination quality photographs:
-before attempting to life any two-dimensional footwear impressions
Impressions must be photographed:
-before lifting is attempted
Gelatin layer is:
-low tach with minimal stickiness
Shoemakers
-made shoes
GLScan utilizes a:
-moveable vacuum bed to hold the gelatin flat and passes the gelatin beneath the line scan camera and a high intensity light
Using chemical Reagents to Detect and/or Enhance
-numerous formulations exist for this purpose and are the same or similar to those used in fingerprinting -nonporous substrates allow for high quality impressions and are generally easy to work with - porous substrates can be challenging and do not always allow for the best replication of detail
Film should never be covered in:
-plastic or stored in a plastic bag
Dry Origin Impressions
-produced when both the shoe and surface are dry -Dry shoes track on dry surfaces -Dry materials do not bond to the substrates -can be developed chemically or physically -easily destroyed -bright oblique lighting or ESL to observe
Randal Holme's sizing was based on:
- 1/4 inch system
Shoe widths are in what incriminates
- 1/4th inch
Half sizes are in what incriminates
- 1/6th inch
Manufacturers will typically allow for what mm difference in length of half sizes?
- 4.23 mm differenced
Fingerprint rollers can result in a:
- 5 mm difference in length
Prototypes of shoes are generally produced in a size?
- 7
Manufacturers will typically allow for what mm difference in length of outsole?
- 8.46 mm
Recovering Blunt Force Pattern evidence:
- Contact can simultaneously transfer blood, soil, etc. to the skin -examination photos must be made -Alternate light sources and chemical enhancements may be utilized for lifting impression -clothing can also be evaluated for patterns -shaving areas of the body may be required - patterns may be traced using clear acetate
Two categories of injuries:
- Dynamic loaded - Static loaded
Lifting with dental stone for indented impressions
- Indentation materializer -Electrostatic Detection Apparatus
Two additional physical methods:
- Iodine fuming - Cyanoacrylate Fuming
May 1965
-Japanese newspaper -three police department ID experts -SGT. Toma -Static electricity to reproduce footmarks -woolen cloth to produce a static charge and celluloid sheets as lifting material
Which techniques are non destructive and should always be utilized first?
- Specialized lighting and forensic photography
Using Alginate Materials
- Use of casting materials to lift blood marks from porous substrates - mix alginate, apply with spatula to porous substrate, let set, then remove - traces of blood on alginate must now be fixed with 5-sulfosalicylic acid - treat with choice of chemical reagents by immersion
Mondopoint:
- a concept intended to become an international standard -not commonly used
If airpockets are a problem:
- a fingerprint roller can be used to smooth these out
In order for a blunt force trauma injury to occur:
- a large amount of force must be applied very rapidly, such as in the case of a kicking or stomping action
Electrostatic lifts should be stored in:
- a new high quality paper stock file folder or a photographic box -taped in place
Scanners or cameras can attain:
- a quick measurement of a person's feet while producing 3D measurements
There is correlation between the length of the foot, shoe size, height, and outsole dimensions, but
- also reflect the limitations of those correlations if trying to accurately predict the exact shoe size or exact height of a person leaving a footwear impression
Methods of Enhancing Two-Dimensional Impressions:
- alternate light sources, specialized lighting and forensic photography - physical methods - chemical reagents for bloody and nonblood impressions - digital enhancement techniques
Reagent use and DNA
- always take blood samples first if that is possible -older procedures tend to be adversely effected by most of the chemicals - newer procedures utilizing STR do not appear to be affected
Factors affecting the severity, extent and appearance of blunt force trauma injuries:
- amount of force delivered to the body - time over which the force is delivered - region struck - extent of body surface over which the force is delivered - type of weapon - condition of body being struck
Chemical Enhancement Safety Concerns:
- any method involving the use of chemicals should be conducted under a ventilated hood or other specialized devise -gloves, goggles and protective clothing must be worn to avoid contact with eyes, skin -consult material safety data sheets about hazards or precautions that need to be considered while using various chemicals or chemical reagents
Thomas Beard
- arrived on the Mayflower - America's first well-documented shoemaker
Fixing blood with 5-Sulfosalicylic Acid before further chemical enhancement
- blood and blood marks are water soluble in water -if not fixed could be destroyed - Aids in permanently adhering bloody residue to the substrate -precipitates the basic proteins which prevents leaching or diffusion of the blood
How many different american shoe widths are there
-15 (AAAAAA to EEEEEE)
Must allow the lifting film to stay in place for at least:
-2 second after the completion of the process
Must remain in place at least____minutes:
-5 minutes before removing
Blunt Force Trauma Wounds:
-Abrasions -Contusions -Lacerations -Fractures of the skeletal system
1880:
-American Edwin B. Simpson introduced the first detailed shoe sizing system
1883:
-Jan Ernst Matzeliger invented the first lasting maching
Most common shoe sizes vary depending on:
-Category of use
1839:
-Charles Goodyear developed the vulcanization process of curing rubber which made it possible to produce footwear with rubber soles
Protein Stains or Dyes
-Colorize the protein components in the blood -impressions can be photographed and/or possibly lifted with gelatin lifters -some reagents will allow the impression to be photographed with fluorescence -some dyes or stains can result in irreversible background staining - colored dyes and stains are best utilized on nonporous substrates where background staining will not be problematic
The Brannock Device cannot be used to:
-Convert a measurement of a shoe impression to a shoe size
Pathfinder ESL Unit:
-Developed by Robert Milne in 1995 -Handheld portable wireless unit -4x6 inches -High voltage, low amperage
1846:
-Elias Howe invents the sewing machine
First recorded shoe sizing was introduced in:
-England in 1688 -Randal Holme
Gelatin Lifters can be photographed or scanned using:
-GLScan
1858:
-Lyman Blake invented sewing machine to attach the sole of a shoe to the upper
Modern Units
-Main unit: housing a rechargeable battery-operated, high voltage source of approx. 10,000 to 15,000 volts -ground plate -metal hand-held probe - special lifting film -rubber roller
Where did shoe factories appear in late 1800s
-Massachusetts
Are shoe sizes always the same from style to style?
-No
Giles and Vallandigham:
-Relationship between foot length and height varies perhaps between 14 and 17% from birth to death, by sex, and among the world population -Using the correlation between height and foot length for forensic science goals is complicated by differing ways of measuring the latter
American sizing for women is:
-different than men
Dry origin impressions are often:
-difficult to see under regular lighting due to their lack of contact with the substrate
Supplies for lifting 2D impressions:
-electrostatic lifting device -footprint size gelatin and adhesive lifting material -silicone casting materials
Gelatin used when:
-fingerprint powders have developed impressions
1983:
-foster and freeman -first commercially available portable high-voltage ESL
Gelatin Lifting vs ESL wet impressions:
-gelatin lifters are best because ELS is not going to be able to lift them
Higher percentage of cases contain footwear impression evidence that is:
-latent or barely visible
Dry origin
-shoe and receiving surface are dry when the impression is made
Gelatin lifters are covered with a clear sheet that requires:
-significant force to remove -studies to determine if this can change the size of the lift have not been conclusive
Use an oblique light to determine if:
-the impression was lifted
Lifting
-the process of transferring a two-dimensional impression from its original surface to a surface that will provide better contrast
When lifting, a CSI or footwear examiner must:
-transfer the impression from the original substrate to one of the better contrast
Poor grounding may occur with:
-uneven or textured surfaces
Carefully peel back the film from one corner
-using great caution not to disturb the impression
What two discoveries contributed significantly to the mass production of footwear in the 19th century?
-vulcanization process of curing rubber ( rubber soles ) -Sewing machine
There is no single step-by-step procedure or list of materials that will always work for every impression:
-when CSI have many appropriate lifting materials and enhancement techniques at their disposal and the experience of using them, they will be best equipped to make good choices and have productive results
Nike has always used what size difference for women to mens shoe?
1.5 size