Forensic footwear evidence

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Crime scene photograph of an unidentified murder victim found in Kansas in 1973 Garnett John Doe shoe.jpg
Crime scene photograph of an unidentified murder victim found in Kansas in 1973

Forensic footwear evidence can be used in legal proceedings to help prove that a shoe was at a crime scene. Footwear evidence is often the most abundant form of evidence at a crime scene and in some cases can prove to be as specific as a fingerprint. Initially investigators will look to identify the make and model of the shoe or trainer which made an impression. This can be done visually or by comparison with evidence in a database; both methods focus heavily on pattern recognition and brand or logo marks. Information about the footwear can be gained from the analysis of wear patterns which are dependent on angle of footfall and weight distribution. Detailed examination of footwear impressions can help to link a specific piece of footwear to a footwear imprint as each shoe will have unique characteristics.

Contents

Types of footwear evidence

Footwear evidence can come in at least three forms, footwear outsole impressions, footwear insole impressions and footwear trace evidence.

Footwear outsole impressions

Footwear outsole impressions are impressions left on an object that was caused by contact with a piece of footwear. These can be left on the ground or raised surface by persons treading over it, left on doors or walls by persons attempting to kick or climb over a wall or even left on other persons after being kicked or stomped on.

Shoeprints left on a dusty surface Shoeprint dusty.jpg
Shoeprints left on a dusty surface

There can also be latent impressions not easily visible to the naked eye, on many different surfaces such as floor tiles, concrete or even carpet. Detection may require the use of additional specialized light sources such as portable ultraviolet lighting. Recovery typically includes photography as well as lifting with "gel" or "electrostatic" dust lifters.

Footwear insole imprints

Imprints of a person's foot can be left on the insole (inside) of footwear. Due to the sweat and dirt from the foot the insole impression can be left regardless of the wearers foot being in a sock or other covering. The size and arrangement of foot and toe imprints can be used to determine whether a person has worn a piece of footwear. The analysis and comparisons of foot imprints is part of the discipline of forensic podiatry. The insole will show a virtual image of the bare foot print of the wearers foot. This can be compared to the actual barefoot print of the shoe owner to gain a match. A 3d optical surface scan can then be used to build up a model of the foot itself. Useful in forensic evidence casting and identification. H Farmer BSc Hons Fs 2018

Footwear trace evidence

Footwear trace evidence is trace evidence that is recovered from footwear. Types of trace evidence that could be recovered include skin, glass fragments, body hair, fibers from clothing or carpets, soil particles, dust and bodily fluids. The study of this trace evidence could be used to link a piece of footwear to a location or owner. DNA can be one of the contributing factors in forensic footwear evidence.

Detection of footwear evidence

Footwear impression revealed by oblique lighting Footwear impression detection light.jpg
Footwear impression revealed by oblique lighting
Footwear impression details revealed with fingerprint powder Footwear impression detection powder.jpg
Footwear impression details revealed with fingerprint powder

Footwear impressions can be detected with a variety of methods including:

Alternate Light Source

Alternate light source is the use of a bright white light, such as a flashlight, to better see dusty prints on the ground that may not otherwise be visible to the eye. An alternate light source is usually used by applying oblique lighting to an area of floor to more easily locate footprints to be lifted. [1]

Fingerprint Powder

Similarly to the use of fingerprint powder in fingerprint analysis, fingerprint powder is used when there is a latent footprint that is composed of mostly oils, instead of dust or dirt. The use of fingerprint powder allows the analyst to more easily find the print and identify the characteristics of the print. [2]

Other Visualization Methods

In the case of visualizing footprints, sometimes spray paints are also used to see the details of the impression better, especially in cases of prints in snow which can be tricky to photograph without being spray painted first.

Recovery of footwear impression evidence

Footwear evidence occurs most often as either footwear impressions left in a soft surface, such as mud, or as dust deposits, which are difficult for the human eye to detect. At violent crimescenes footmarks can be left as a result of a person standing in blood and subsequently trailing it as they move around the scene. The recovery of footwear evidence involves fixing and lifting or casting of the prints to preserve the details of the print and be used for further analysis and comparison.

Lifting

Footwear impressions can be lifted from surfaces with tools such as adhesive lifters, gelatin lifters or electrostatic lifting devices. These methods are similar to that of fingerprint lifting, which are lifted using one of the previously mentioned methods and then placed on a black or white backing card (depending on the color of the print substrate) to better see the details of the print and for evidence preservation purposes. [3] Adhesive lifters are essentially pieces of tape with a backing on them that are smoothly applied to the print, lifted off of the print and then attached to a backing card. Gelatin lifters are flexible gel sheets made of gelatin which are applied to the 2D impression in the same manner as adhesive lifters and then are covered by the plastic sheet provided with the gelatin lifters. [4] Electrostatic lifting involves the use of high-voltage current on a lifting plate to lift the elements of the print, without disturbing the area as much as traditional lifting methods do, followed by transferring the print from the lifting plate to a gelatin lifter or adhesive lifter. [3]

Casting

Evidence left via impressions can generally be recovered utilizing a plaster cast or dental stone. Initially the impression is isolated by framing the area with a solid boundary. Following this a plaster mix can be gently poured inside the frame; it is generally considered not best practice to pour directly onto the impression. In some cases where the surface is not ideal for casting prior techniques can be utilised to gain a better cast of the impression. Sand can often be fixed in place by applying an aerosol resin or glue although hair spray is often used in combination with chalk to assist in ease of lifting the cast out of the print more gently. Wet mud impressions can be dried using a combination of pipetting water from the surface and applying hot air, often in the form of a hair dryer.

Fixing Techniques

When using plaster to cast a footprint, it is recommended to use a fixing agent to prevent the loss of detail when creating a plaster cast. These fixing agents include shellacs, glues, aerosol resins and hairsprays, which are sprayed liberally on the print before pouring the plaster of Paris into the impression. [5] Often times, chalk is also applied to the impression as an added protective measure against damaging the print.

Plaster/Dental Stone

Generally speaking, plaster of Paris and dental stone are mixed in the same way at a scene, usually by adding water to the powder in a baggy until a thick, but pourable consistency and then pouring the mixture indirectly into the impression. [6] After the plaster/stone is applied it is allowed to set and then gently lifted out of the impression. The reason that plaster and dental stone are not used in snow prints is because dental stone heats up as it sets, while prill sulfur will only cool down as it sets.

Prill Sulfur

In instances where there are impressions in snow or slush, prill sulfur is used to avoid melting the impression substrate. Prill sulfur is prepared by melting the sulfur on a hot plate in a well ventilated area and then allowing the mixture to cool, while stirring continuously. [7] The sulfur mixture can then be poured into the impression and left to set and then analyzed.

3D Optical Surface Scanning

Footwear evidence can be recovered with use of 3D scanners.

There are two types of 3D scanners used in forensics:

Advantage of 3D scanning over casting is that 3D scanners can scan the object without touching or affecting it – most 3D scanners use lasers to capture 3D information. Some scanners can also capture the colour surface, [null producing] a visually [null accurate] replica of the object. To create a complete and highly detailed 3D model of a footprint less than 15 minutes is required. HF 2018

Three-dimensional imaging

Recent approach takes advantage of digital photography. A set of digital images of a footmark or target area of interest, taken in different viewpoints is required to create detailed and accurate 3D model. Appropriate software allows to visualise a 3D model in different ways, make accurate measurements from a 3D trace or perform a comparison of multiple traces.

Examination of footwear impressions evidence

Footwear impression can reveal information that may be of use to forensic investigators. Analysis of impressions found at a crime scene may provide the following information:

Number of people at a crime scene: Different footwear impressions left at a crime scene will indicate more than one person was present at the crimescene.
Approximate height of the wearer: There is statistical correlation [9] between foot/footwear size and height and also stride length and height. The dimensions of the footwear impression and the distance between impressions can be used to provide an estimate of height.
Activity of wearer when impression was made: Plastic footwear impression left on soft surfaces can reveal whether a person was walking, running or carrying a heavy load when the impression was made. An impression made by person running will make impressions that are deeper in the heel and toe sections. A person carrying a heavy load such as a body will leave imprints that are deeper than when not carrying a heavy load.
Manufacture, model and approximate size of footwear: Footwear impression can show the design elements (shapes, patterns, arrangement) that form the outsole design. These can be compared with a footwear outsole database to identify the model of footwear that made the impression. Knowledge of the model of footwear that made the impression can assist in narrowing down the list of suspects and can also be used to link multiple crime scenes to the same perpetrator(s).
Establish link between crime scene impression with a specific piece of footwear: Comparison of crime scene impressions with a specific piece of footwear recovered from a suspect can determine if there is any relationship. A worn piece of footwear will gradually acquire unique wear and tear on the outsoles. These randomly acquired characteristics will be unique to that specific shoe and may show in crime scene impressions.

Limitations of footwear evidence

The Unabomber, Theodore Kaczynski, was known to keep shoes with smaller soles attached to the base in order to confuse investigators about the size of the suspect's feet. [10]

There is a lack of scientific research and evidence to support footprint evidence in criminal investigations and convictions. While footwear evidence has appeared to be useful in some high-profile cases, such as Richard Ramirez’s (aka The Night Stalker) unique ‘Avia’ shoeprints helped investigators link together his crimes, it must be evaluated cautiously. In the Ramirez case the footwear impressions used to link his crimes were not the primary evidence used to convict him of his crimes. [11] There have been cases where footprint evidence has assisted in wrongful conviction, such as Charles Irvin Fain who was wrongfully convicted and sentenced to death row. [12] The forensic investigator testified that the shoe prints found at the crime scene matched the ‘walking gait’ of Fain, though analysis of this type has never been scientifically validated. Fain was later exonerated based on DNA evidence after almost 18 years on death row.

It must also be considered that footprints discovered at a crime scene remain fixed, while the wearer of the footwear continues on likely changing the wear of the shoe. Thus, unless the print is immediately matched its potential value may be lost. Also of concern is the lack of science and standards demonstrating that footwear marks are unique. There are a lack of scientific studies demonstrating how many characteristics are needed to determine a match with such evidence. This is similar to other forensic evidence such as bite mark analysis, tire tread analysis, etc. where there is little scientific evidence of its efficacy. In 2009, the National Academy of Sciences made the conclusion that, aside from DNA, there was little if not any, scientific evidence for many forensic disciplines, including footprint evidence. [13]

Footwear databases

Forensic investigators can use computerized footwear databases to quickly compare the class characteristics such as tread design and possibly identify a manufacturer, brand, and model to the ones stored in the database.

Footwear Software

High profile cases

See also

Related Research Articles

<span class="mw-page-title-main">Forensic science</span> Application of science to criminal and civil laws

Forensic science, also known as criminalistics, is the application of science principles and methods to support legal decision-making in matters of criminal and civil law.

<span class="mw-page-title-main">Fingerprint</span> Biometric identifier

A fingerprint is an impression left by the friction ridges of a human finger. The recovery of partial fingerprints from a crime scene is an important method of forensic science. Moisture and grease on a finger result in fingerprints on surfaces such as glass or metal. Deliberate impressions of entire fingerprints can be obtained by ink or other substances transferred from the peaks of friction ridges on the skin to a smooth surface such as paper. Fingerprint records normally contain impressions from the pad on the last joint of fingers and thumbs, though fingerprint cards also typically record portions of lower joint areas of the fingers.

<span class="mw-page-title-main">Forensic dentistry</span> Aspect of criminal investigation

Forensic dentistry or forensic odontology involves the handling, examination, and evaluation of dental evidence in a criminal justice context. Forensic dentistry is used in both criminal and civil law. Forensic dentists assist investigative agencies in identifying human remains, particularly in cases when identifying information is otherwise scarce or nonexistent—for instance, identifying burn victims by consulting the victim's dental records. Forensic dentists may also be asked to assist in determining the age, race, occupation, previous dental history, and socioeconomic status of unidentified human beings.

<span class="mw-page-title-main">Crime scene</span> Location that may be associated with a committed crime

A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSI) and law enforcement. The location of a crime scene can be the place where the crime took place or can be any area that contains evidence from the crime itself. Scenes are not only limited to a location, but can be any person, place, or object associated with the criminal behaviours that occurred.

In forensic science, Locard's principle holds that the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence. Dr. Edmond Locard (1877–1966) was a pioneer in forensic science who became known as the Sherlock Holmes of Lyon, France. He formulated the basic principle of forensic science as: "Every contact leaves a trace". It is generally understood as "with contact between two items, there will be an exchange." Paul L. Kirk expressed the principle as follows:

Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibres from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.

<span class="mw-page-title-main">Trace evidence</span> Type of evidence of physical contact

Trace evidence occurs when objects make contact, and material is transferred. This type of evidence is usually not visible to the naked eye and requires specific tools and techniques to be located and obtained. Due to this, trace evidence is often overlooked, and investigators must be trained to detect it. When it comes to an investigation trace evidence can come in many different forms and is found in a wide variety of cases. This evidence can link a victim to suspects and a victim or suspect to the crime scene.

Forensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts".

An electrostatic detection device, or EDD, is a specialized piece of equipment commonly used in questioned document examination to reveal indentations or impressions in paper that may otherwise go unnoticed. It is a non-destructive technique, allowing further tests to be carried out. It is a sensitive technique capable of detecting indentations on pages several layers below the top sheet and many years after the indentations were created.

<span class="mw-page-title-main">Footprint</span> Impressions or images left behind by a person walking or running

Footprints are the impressions or images left behind by a person walking or running. Hoofprints and pawprints are those left by animals with hooves or paws rather than feet, while "shoeprints" is the specific term for prints made by shoes. They may either be indentations in the ground or something placed onto the surface that was stuck to the bottom of the foot. A "trackway" is a set of footprints in soft earth left by a life-form; animal tracks are the footprints, hoofprints, or pawprints of an animal.

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A removable shoe insert, otherwise known as a foot orthosis, insole or inner sole, accomplishes many purposes, including daily wear comfort, height enhancement, plantar fasciitis treatment, arch support, foot and joint pain relief from arthritis, overuse, injuries, leg length discrepancy, and other causes such as orthopedic correction and athletic performance.

<span class="mw-page-title-main">Forensic photography</span> Art of producing an accurate reproduction of a crime scene

Forensic photography may refer to the visual documentation of different aspects that can be found at a crime scene. It may include the documentation of the crime scene, or physical evidence that is either found at a crime scene or already processed in a laboratory. Forensic photography differs from other variations of photography because crime scene photographers usually have a very specific purpose for capturing each image. As a result, the quality of forensic documentation may determine the result of an investigation; in the absence of good documentation, investigators may find it impossible to conclude what did or did not happen.

The following outline is provided as an overview of and topical guide to forensic science:

<span class="mw-page-title-main">Forensic geology</span>

Forensic geology is the study of evidence relating to materials found in the Earth used to answer questions raised by the legal system.

<span class="mw-page-title-main">Comparison microscope</span>

A comparison microscope is a device used to analyze side-by-side specimens. It consists of two microscopes connected by an optical bridge, which results in a split view window enabling two separate objects to be viewed simultaneously. This avoids the observer having to rely on memory when comparing two objects under a conventional microscope.

<span class="mw-page-title-main">Forensic tire tread evidence</span> Analysis of tire treads at crime scenes

Forensic tire tread evidence records and analyzes impressions of vehicle tire treads for use in legal proceedings to help prove the identities of persons at a crime scene. Every tire will show different amounts of tread wear, and different amounts of damage in the form of tiny cuts and nicks. These unique characteristics will also show on the impression left by the tire.

<span class="mw-page-title-main">Forensic podiatry</span>

Forensic podiatry is a subdiscipline of forensic science in which specialized podiatric knowledge including foot and lower-limb anatomy, musculoskeletal function, deformities and diseases of the foot, ankle, lower extremities, and at times, the entire human body is used in the examination of foot-related evidence in the context of a criminal investigation. Forensic Podiatry has been defined as:

The application of sound and researched podiatry knowledge and experience in forensic investigations, to show the association of an individual with a scene of crime, or to answer any other legal question concerned with the foot or footwear that requires knowledge of the functioning foot.

The Integrated Automated Fingerprint Identification System (IAFIS) is a computerized system maintained by the Federal Bureau of Investigation (FBI) since 1999. It is a national automated fingerprint identification and criminal history system. IAFIS provides automated fingerprint search capabilities, latent searching capability, electronic image storage, and electronic exchange of fingerprints and responses. IAFIS houses the fingerprints and criminal histories of 70 million subjects in the criminal master file, 31 million civil prints and fingerprints from 73,000 known and suspected terrorists processed by the U.S. or by international law enforcement agencies.

<span class="mw-page-title-main">Glove prints</span> Mark left on a surface by a worn glove

Glove prints, also sometimes described as gloveprints or glove marks, are latent, fingerprint-like impressions that are transferred to a surface or object by an individual who is wearing gloves.

<span class="mw-page-title-main">Murder of June Anne Devaney</span> 1948 child murder in Blackburn, England

The murder of June Anne Devaney is a British child murder which occurred on 15 May 1948 when a girl aged 3 years 11 months was abducted from her cot while an inpatient at Queen's Park Hospital in Blackburn, Lancashire. The child was removed to the grounds of the hospital, where she was raped, before suffering extensive blunt force trauma to her skull when her head was repeatedly swung into a sandstone wall. The assault caused extensive internal injuries and multiple skull fractures, causing the child to develop a fatal state of shock. Her murderer, 22-year-old Peter Griffiths, was arrested three months after the crime and was subsequently tried and convicted of June Anne's murder. He was hanged on 19 November 1948.

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