Comparing a crime scene shoe print on a hard surface, or an impression in dirt, mud, or snow, to the bottom of a specific shoe, is not unlike the process of latent fingerprint identification. In many crime laboratories, the latent fingerprint people also handle footwear and tire-track evidence, and occasionally the identification of tool marks. Compared to DNA analysis, toxicology, and various aspects of forensic pathology, the identification of shoe marks, latent fingerprints, crime scene bullets, tool marks, and handwriting, involves less science than it does informed observation.
A crime scene shoe print or impression can be identified as part of a footwear group according to size, brand, and model, or identified as coming from one shoe to the exclusion of all other shoes. Every year 1.5 billion pairs of shoes are sold in the United States. At any given time, there could be as many as 100,000 pairs of size ten Nike sneakers of a certain model and tread design. There could be, say, 5,000 pairs of these shoes in circulation in the Chicago area alone. The criminalistic or incriminating value of a group identification depends upon the size of the group. These group, or class identifications occur when the crime scene print or impression is not detailed enough for a match to a specific shoe, or when the shoe that made the mark is not available for comparison.
The most famous group identification of shoe prints came at O. J. Simpson's double murder trial when FBI expert William Bodziak identified several crime scene prints in blood as having been made by a pair of size 12 Bruno Magli Lorenzo shoes, luxury footwear made in Italy. Bodziak's testimony tended to incriminate Simpson in two ways: the identification involved a relatively small footwear group, and Simpson, after denying that he owned Bruno Magli shoes, was seen on television wearing a pair. The actual shoes that made the bloody prints were never located.
An individual shoe, boot, or sandal can be linked to a crime scene print or impression the way a latent fingerprint can be matched to its inked, rolled-on counterpart. Instead of comparing ridge configurations, the footwear examiner looks at a shoe's sole and heel for unique signs of wear that show up in the print or impression. Every shoe that has been worn for awhile is as unique as a fingerprint. The more wear, the more potential for identification.
Footwear identification, unlike fingerprint matching, does not require a minimum number of similarity points to be admissible in court. The credibility of a shoe identification depends upon the training, experience, and objectivity of the examiner, as well as the quality, clarity, and uniqueness of the characteristics being compared. New methods and techniques are constantly being developed, for example, to lift footwear impressions from dust, and even preserve shoe prints made in snow.
Shoe prints left in dust, blood, or soot are photographed (next to a reference ruler), then peeled off the surface the way a latent fingerprint is lifted. Footwear impressions are often preserved with plaster-of-paris casts of the depressions. Shoes and their crime scene prints and impressions can be compared side-by-side, or through the use of transparent overlays. To connect a suspect to a crime scene through footwear evidence, detectives need three things: a good print or impression; the shoe that made it; and a way to link the suspect to the footwear. In the O. J. Simpson case, the detectives had shoe prints in blood, but none of the footwear in Simpson's possession matched the murder scene evidence. The prosecution had to settle for a group identification.
Dr. Louise Robbins and her "Cinderella Analysis"
Fortunately for O. J. Simpson, the world's only footwear identification expert who might have identified the crime scene prints as having been made by shoes worn by him without having access to the actual footwear, had died eight years before his trial. Dr. Louise Robbins, an anthropology professor at the University of North Carolina at Greensboro, wasn't interested in matching the bottoms of shoes to corresponding crime scene latents. She would have claimed she could identify the crime scene prints in the Simpson case by examining other shoes in Simpson's possession. Robbin's method of identification, a process she called "wear pattern analysis," was based on her theory that no two people have the same shaped feet, or walk in exactly the same way. According to her, this unique feature reveals itself inside the shoes people wear, and in the prints or impressions they leave behind.
Dr. Robbins claimed she could look at a crime scene shoe print and determine that it had been made by the wearer of shoes other than the one shoe that had actually left the crime scene mark. Her critics, and there were many, called this her "Cinderella Analysis." If a defense attorney had a client in a case in which Dr. Robbins was testifying for the prosecution, that defendant's foot always seemed to end up fitting the shoe that had made the crime scene print or impression. The jury, without access to the actual source of the crime scene mark, simply had to take her word for it. It's not surprising that prosecutors with insufficient footwear evidence, and weak cases, loved this woman. Defense attorneys called her the prosecution expert from hell.
In her work as an anthropologist, Dr. Robbins had frequently exhibited the ability to see things that her colleagues could not. When working in Africa, she garnered worldwide publicity after identifying a 3.5 million-year-old fossilized footprint as made by a woman who was five and a half months pregnant. Dr. Timothy White, a professor of anthropology at the University of California at Berkeley, who had worked with Dr. Robbins in Africa, characterized her conclusions as pure nonsense.
If Dr. Robbins had confined her ideas to the classroom, she would have been harmless, and no one would have been greatly bothered by her patently ridiculous theories. But in 1976, when she took her nonsense into the courtroom as a forensic footwear identification expert, people not only started to worry, defendants started going to prison. Between 1976 and 1986, Dr. Robbins testified, for fees up to $9,000 a case, in ten states and Canada. During this period at least 12 defendants went to prison on the strength of her expert testimony. Her career as an expert witness came to an end in 1987 when she died of brain cancer at the age of 58.
In the year of Dr. Robbin's death, the American Academy of Forensic Sciences sponsored a panel of 135 anthropologists, forensic scientists, lawyers, and legal scholars to review her cases and work. The panel concluded that her identification methodology had no basis in science. Marvin Lewis, a law professor at John Marshall University, called her work "complete hogwash." Lewis, who operated an expert witness referral service, was dismayed that so many judges had qualified Robbins as an expert witness. Russell Tuttle, a professor of physical anthropology at the University of Chicago, in referring to Dr. Robbins, said, "Why do we allow this kind of rot, this pseudoscience, into our courts?" FBI expert William Bodziak, who had testified against Dr. Robbins in several murder trials, agreed: "Nobody else has ever dreamed of saying the kinds of things she said."
Dr. Robbins not only wormed her way into courtrooms, and the hearts of desperate prosecutors, she had impressed juries. She had a Ph.D, taught at a major university, and had been written up in Time Magazine. In 1985 she published a book, Footprints: Collection, Analysis, and Interpretation. As a self-validating expert who used scientific terminology to advance an absurd theory, she came off as extremely confident, and sure of her conclusions. Moreover, some prosecutors portrayed her as a pioneer in a new field of scientific identification. One prosecutor, in defending Dr. Robbins against her critics, reminded the jury that it had taken 400 years for Galileo's theories to gain acceptance in the scientific community.