Forensic Podiatry (Part One of Two)
Written by John A. DiMaggio, DPM   

THE TYPICAL LAYPERSON would have a difficult time explaining the difference between the job descriptions of footwear examiners and forensic podiatrists. Experts in both disciplines are able to deal with evidence left by feet or footwear at a crime scene, but in most cases a foot-wear examiner and a forensic podiatrist will bring with them their own area of expertise and specific realm of study.

Probably more familiar to most law-enforcement professionals, the footwear examiner is generally a criminalist who is trained to evaluate footwear evidence for class and individual characteristics. By identifying and comparing these characteristics, it is possible to match an impression left at a crime scene with the shoe worn by a suspect, for example. It is a pattern-evidence specialty, one that is in the same class as latent-fingerprint examination.

Forensic podiatry, on the other hand, is the evaluation of evidence relating to the human foot—technically termed pedal evidence—for the purpose of connecting an individual to footwear or a footprint. This area of expertise usually requires someone who has a background in podiatric medicine—in other words, it is usually a person who has dedicated their study to the structure of the foot, ankle, knee, leg, and hip.

A forensic podiatrist may be called upon to work as a member of the forensic team in a variety of situations and for a number of different types of evidence, including the following:

  • The examination of footprints, either made by bare feet or sock-clad feet, most commonly visible prints made with blood;
  • The examination of foot impressions in a substrate;
  • The examination of footwear, particularly when there is a question of the predominant wearer or ownership of the questioned footwear;
  • Footprint profiling; and
  • Mass-disaster applications.

Figure 2—Bare footprint and outline

 

Brief history of forensic podiatry

The field of forensic podiatry has made remarkable progress over the past 20 years. Podiatrists have been involved in casework since the early 1970s and podiatrists from Canada, the United States, Great Britain, Australia, and New Zealand have worked as individuals on multiple cases.

One of Arizona’s most notorious murders took place around midday on December 2, 1989, when James Styers and Roger Scott took Christopher Milke, the four-year-old son of a female friend (Debra Milke), from his home. They told him he was going to see Santa Claus at a local shopping mall. Instead, they took him to the desert northwest of Phoenix. At that location, they shot him three times in the back of the head, execution style, with a .22-caliber RG revolver loaded with CCI Stingers.

Some shoe prints were among the evidence recovered at the scene in the desert. An integral part of the testimony in court centered on footwear that was later found hidden in the bushes at a shopping mall. The shoes were identified as belonging to one of the suspects based on podiatric findings: his foot size, shape, and biomechanical and pathologic deformities. All three of the defendants in this case were convicted and sentenced to death.

In 2003, the American Society of Forensic Podiatry (ASFP) was formed by a group of podiatrists to institute protocols and procedures necessary to establish a formal discipline. Forensic podiatrists have been associate members of the International Association for Identification (IAI) in the Footwear and Tire Track Committee for over 20 years. In 2007, forensic podiatry was recognized as a forensic discipline by the IAI when the organization formally established a Forensic Podiatry Com-mittee. Podiatrists are also members of the American Academy of Forensic Sciences (AAFS).

When to seek the help of a forensic podiatrist

There are a variety of scenarios in forensic cases where the assistance of a podiatrist may be required. For example: A footwear examiner may be able to make a positive identification between questioned footwear impressions and a suspect’s shoe, but the suspect may deny ownership of the shoes—or a footwear examiner’s findings may be inconclusive. In those cases, there may be enough clues available that a forensic podiatrist can use as cues in order to establish the suspect as the predominant wearer of the questioned footwear. There are other cases where multiple wearers may be involved. This can be ascertained by a forensic podiatrist, depending on variables such as the quality of the evidence, shoe condition, or extent of wear.

Bloody footprints are often found at crime scenes. Occasionally, there may be enough consecutive foot falls to allow for gait analysis that can be helpful in correlating a deformity or biomechanical imbalance to a particular individual. When bare footprints are recovered, there are many opportunities to make multiple determinations relative to an individual. Foot profiling, which in many applications will render “approximations”, can be used to determine an individual’s height or shoe size. Other possibilities may include determining gender and biomechanical or pathologic problems that may be evidenced in a specific foot type. Morphologic characteristics, such as a fat, fleshy foot may be attributable to a certain body type. Further study and research is required in some of these areas to ultimately add to the ability of the examiner to maximize the use of this kind of evidence.

Qualification of the forensic podiatrist

The forensic podiatrist usually will be a podiatrist who has been in practice for a number of years and has acquired the necessary clinical experience that can be helpful in dealing with the nuances encountered by the dynamic foot. The podiatrist should have a general knowledge and appropriate training in the criminal-justice system, along with membership and participation in professional organizations such as the IAI, ASFP, and AAFS.

Figure 1—Bloody footprints on wooden floor; Figure 3—The PedoGRID measurement system

How to work with a podiatrist:

Gather the right information

The success of any evaluation, whether it ultimately leads to an identification or an exclusion, depends on two main things: 1) The ability of the examiner and 2) the quality of the evidence that is presented for examination, along with the quality of the exemplars used for comparison purposes.

In many examinations, photographs may be the only form of evidence that represents the unknown (or suspect) pedal evidence. In the context of this article, there is no intent to simplify or make any assumptions relative to photographic techniques. An experienced photographer can be a tremendous asset to any discipline in creating the most appropriate representation for examination purposes.

Examination-quality photographs in natural size (1:1) are required. Orienta-tion photographs may be needed for review. It is very important that the photo-graphs at the crime scene are taken perpendicular to the plane of the evidence and that the scale is at the same level as the evidence. If, for example, we are dealing with a foot impression in sand, then the scale can be placed in the actual impression at the level of its lowest point or adjacent to the impression at a similar depth. If this is not possible, it may be necessary to perform some calculation considering variables that could lead to distortion and inaccuracy in the one-to-one enlargement.
Let us presume that we have bloody bare footprints with no usable ridge detail on a wooden floor at the crime scene and we have a suspect in custody (see Figure 1). The photographic representations are good and now we need to obtain some exemplars for comparison purposes.

This would be the appropriate time for the podiatrist and the criminalist to have a discussion in order to determine what exemplars are needed, based on known facts about the case.

In many situations, members of a forensic team have never worked with bare foot impressions, nor have they worked side-by-side with a forensic podiatrist. Because this is new territory for many crime-scene and forensic personnel, it is important to work with the forensic podiatrist to make sure the exemplars are collected correctly. The process is certainly something that most criminalists can be trained to perform and add to their armamentarium of expertise. Unfortunately, to this date there have been few—if any—training workshops that were specifically involved in these techniques.

Departments can request a list of protocols for acquiring various exemplars for podiatric evaluation from the ASFP. (Note: You will find contact information for the ASFP at the end of this article.) The need for consistency and reproducibility is basic, and we all need to be on the same page to lead to a successful conclusion, whether it ultimately leads to positive identification or to exclusion.

Collecting exemplars for case evaluation

Here are a few of the methods crime-scene or laboratory personnel can use to collect exemplars that the forensic podiatrist will be able to use for a thorough analysis:

  • Bare footprint/outline—This requires the subject to be in an upright, weight-bearing position. Protocols recommend a two-step method. An outline of the soft tissue of the foot should be made with an instrument that is held perpendicular to the weight-bearing surface. It is recommended that you make three exemplars per foot (see Figure 2 on Page 26).
  • Gait pattern—This is not always required by the forensic podiatrist for a case evaluation, but it is good to have in order to show the foot in its dynamic mode. The standard collection method-ology using a 20-foot length of butcher paper needs strict adherence to obtain reliable prints. At least eight steps should be recorded. The first step and the final one or two steps are usually excluded; steps three through six are usually the most representative. In order to ensure accuracy because of intentional influences of the subject being evaluated, three separate patterns should be performed.
  • Foot Measurement—Various devices are available that will provide an approximate foot (or shoe) size. The Brannock device is probably the most common. A new device called the PedoGRID is a convenient tool that can also be used for other measurements and applications (see Figure 3).
  • Foam-block impressions—These are taken in a standing, weight-bearing position. Again, it is always best to have two or three samples (see Figure 4). The foam block is then filled with a dental plaster to create a casting of the foot (see Figure 5).
  • Photographs—A forensic podiatrist may require examination-quality photographs of questioned evidence and additional exemplars. These photo-graphs would include:
    1. The suspect’s feet: Capture images of the suspect’s feet in the standing position. You should take photographs of the feet from a variety of angles, but at the minimum take photographs from the front, rear, on each side, and the bottom.
    2. Footwear: When the footwear is recovered, it can be examined directly or photographically depending on the needs of the case. The footwear should first be evaluated for trace evidence, biological evidence, and other potential evidence by personnel in the laboratory.
    3. Sock liner: Getting good photo-graphs of the sock liner—or the shoe’s insole—is very important in many evaluations because it may contain a virtual image of the foot. This image is usually a two-dimensional reproduction of the foot, although it can be three-dimensional depending on the sock-liner material. This is a very important area where the expert in photography can use various techniques to enhance the image to allow for a better examination (see Figure 6).

Figure 4—Foam-block impression; Figure 5—A casting from the foam block; Figure 6—Example of a sock liner (insole)

Forensic examination of evidence

When all of the materials have been received by the forensic podiatrist, then the examination process can begin. The podiatric methodology essentially follows the accepted standard of analysis, comparison, examination, and verification (ACE-V).

If we continue this discussion with the earlier example of the bloody bare footprints on a wooden floor, our very first responsibility is to analyze the photographs and dissect them into components that can be used for comparison to known exemplars. The comparison process is then performed leading to an ultimate conclusion. This author prescribes levels of certainty to each evaluation in order to better quantify the results and their strengths or weaknesses in the final determination or conclusion.

When reviewing the levels of certainty, it is important to note that an exclusion/non-identification or inconclusive result can be made at any level. The five levels of certainty are:

  • Level 1—The first question asked by the investigator is whether it is a footprint. Is there sufficient quantity or quality to continue in the evaluation process? If the answer is in the affirmative, then we proceed to the next level.
  • Level 2—Is there general agreement in size, shape, and position of the digits and foot zones? If the answer is in the affirmative, then we proceed to the next level.
  • Level 3—Is there sufficient agreement in the identification lines: web-ridge line, arch line, lateral foot line, heel line, and web-space outline? If the answer is in the affirmative, then we proceed to the next level.
  • Level 4—Are the intermediate characteristics sufficient and verifiable? This is where the clinical expertise and knowledge of the practitioner regarding pathological, morphological, and biomechanical imbalances or de-viations are utilized. If the aggregate of these findings are sufficient and can be verified, then the degree of certainty is elevated to Level 5.
  • Level 5—Individual characteristics, either singular or plural, are noted and the Level 4 characteristics are verified by another examiner.

The use of different levels in the determination of certainty may negate the inherent confusion when using standard terminology such as possible or probable. Such terminology has generated some serious points of contention and concern both in the United States and abroad. Presenting the facts in a stepwise fashion seems to be a more logical method. And using this method may ultimately provide the jury with a much clearer picture of the scientific process used, as well as the ultimate conclusion.

Part Two of this two-part article on Forensic Podiatry will be in the May-June issue of Evidence Technology Magazine. It will present measurement and comparison techniques that are commonly used, along with information about the technologic devices that are used to help formulate a final opinion.

For More Information

about collecting exemplars for forensic podiatric examination, you can contact the American Society of Forensic Podiatry at this telephone number: 541-347-3632
E-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it

About the Author:

John A. DiMaggio, DPM, is a forensic podiatrist with Forensic Podiatry Con-sulting Services, PLLC in Bandon, Oregon. He can be reached by e-mail: This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
Or by telephone at this number: 541-347-3632

 


ORIGINALLY PUBLISHED:
"Forensic Podiatry (Part One of Two)," written by John A. DiMaggio, DPM
March-April 2008 (Volume 6, Number 2)
Evidence Technology Magazine
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