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The use of digital photographs is playing a growing role in the creation of courtroom evidence. Approximately 30 million criminal fingerprint submissions were entered into the Automated Fingerprint Identification System and its relatives between October 2002 and May 2003. These systems increasingly rely on digital technology. Is that reliance justifiable? BRANDON MAYFIELD: CAUTIONARY TALE The tale of Brandon Mayfield sounds a cautionary note. Mayfield was released on May 27, 2004, after Spanish officials conceded that fingerprints on a bag left near the Madrid bombing site were not his. However, earlier Mayfield had been mistakenly detained as the person who left the fingerprints. After the March terrorist attack on commuter trains in Madrid, partial latent fingerprints were discovered and lifted from plastic bags that had contained detonator caps. Digital images of the latents were submitted by Spanish authorities to the FBI for analysis. According to the statement issued by the FBI on May 24, the submitted images were searched through the Integrated Automated Fingerprint Identification System (IAFIS). A search compares an unknown print to a database of millions of known prints. The result is a short list of possible matches. A trained fingerprint examiner then takes the short list and performs an examination to determine whether the unknown print matches a known print in the database. In this case, the FBI examiners initially concluded that the latents were Mayfield’s. “Using standard protocols and methodologies, FBI fingerprint examiners determined that the latent fingerprint was of value for identification purposes. This print was subsequently linked to Brandon Mayfield.” Yet “upon subsequent review it was determined that the FBI identification was based on an image of substandard quality.” Apparently, rather than directly analyzing the original image of the latent fingerprints, the FBI examiners compared IAFIS exemplars to digital images provided by the Spanish government. The use of the digital images probably contributed to the mistake. Since digital images have lower resolution, they contain less detail. If the digital images had included the missing details, the more complete images might have made it evident much sooner to the FBI examiners that the latent prints were not Mayfield’s. As the Mayfield case demonstrates, there are pitfalls in reliance on digitized fingerprint evidence. The use of a computerized system to identify a culprit is a multistep process, and there is a possibility of error at every step in the process. Scanning. Before a computer can alter or enhance an image, the image must first be scanned or otherwise entered into the computer. This step raises an input problem. The available scanners are not accurate enough to represent perfectly the photographic images they are asked to scan. Photographic images are often bent to conform to the shape of a computer screen which is also the shape of most computer printers. “Digital imaging for the most part has a long way to go to meet the quality of film,” said Richard Vorder-Bruegge, an FBI forensic expert. In many jurisdictions, Livescan scanners have replaced paper-based fingerprint images. Often there are two available settings on Livescan: some detail and more detail. If the operator chooses the first setting, the scanned image can omit a detail that would lead to the positive exclusion of an innocent person such as Mayfield. Selecting the first setting might be convenient, but it sacrifices accuracy. Indexing. Before the image is stored, it must be linked (indexed) to a specific person. Banking and manufacturing systems frequently automate this step by the use of magnetic ink or bar codes. In contrast, many law enforcement systems rely on fallible human beings to do the indexing. Storage. The indexed, scanned image must be stored for subsequent retrieval. Fingerprints are stored on standard hard drives. However, the hard drives of computer systems are vulnerable; they can be hacked, causing incorrect information to replace correct data. Given the potentially dire consequences of hacking, each data center should be prepared to detect the creation of erroneous information and restore the correct information. However, even some of the largest business firms in the world do not yet have that technical capability. Similarly, many criminal justice data centers currently lack that capability. Retrieval. Once stored, images can be retrieved and re-enhanced or printed. Do not assume that the printout is identical to the original image. Suppose that after the storage of the original image, the center purchases a new and “better” printer. Its printout not only may be different than the image the earlier printer would have produced; there is no guarantee that the printout is more accurate than the image that the earlier printer would have yielded. In sum, the creation of digitized evidence is a multistep process, and many of the steps introduce a possibility of inadvertent mistake. There is also the possibility of deliberate manipulation of the image. The advent of digital photography has made it possible to generate new types of photographs for trial. In the past, using traditional analogy technology, a photographer could produce an enlarged photograph. An enlargement merely increases the size of the image. However, digital technology makes it possible to produce two new types of images: enhanced and restored. Restoration is an additive process, adding new data based upon preconceived ideas about what the end result should look like. The use of image-restoration computer software presents a significant problem in the validation of the underlying scientific process. The proponent must establish the reliability of the software used to manipulate the pixels to create the restored image. The proponent must be able to point to a body of solid empirical research validating the preconception about the end result. To add details, the software predicts the missing details. To be scientifically reliable, the prediction must rest on a substantial body of research. More commonly, digital photography is used today to produce enhanced photographs. Image enhancement is a subtractive process, which improves image contrast by removing interfering colors and background patterns. Like restoration, image enhancement poses a problem in the validation of the scientific process. Image-enhancement technology was developed for NASA. The Jet Propulsion Laboratory of the California Institute of Technology was instrumental in pioneering image enhancement. Due to weight and power limitations of spacecraft, it was impractical for NASA to install state-of-the-art cameras on unmanned craft. The cameras used produced somewhat degraded photographs. Image enhancement reverses the degradation. Researchers studied the degradation properties of the particular types of photographic equipment to capture a certain type of image: If this type of camera is used to photograph distant objects, what type of degradation can be anticipated? Then the researchers design computer software to reverse the degradation and improve the sharpness and image contrast of the photograph. The software eliminates background patterns and colors. Today, forensic scientists use the technology to enhance photographs of fingerprints and palmprints. At first, courts were quite receptive to images created by digital technology. In the early cases, the courts admitted the images based on minimal evidentiary foundations. Nooner v. State, 907 S.W.2d 677 (Ark. 1995), cert. denied, 517 U.S. 1143 (1996); Dolan v. State, 743 So. 2d 544 (Fla. Dist. Ct. App. 1999); State v. Hayden, 950 P.2d 1024 (Wash. App. 1998); Annot., 110 A.L.R.5th 213 (2003). However, more recently there has been sharp criticism of uncritical reliance on digitized evidence. Two of the leading critics are Michael Cherry of Vsolutioncorp and Larry Meyer of State Farm Insurance. As Cherry and Meyer have noted, digital images often contain fewer details than analog images. A negative shot on traditional 200-speed film can produce the equivalent of 18 megapixels of resolution. Only highly specialized, expensive digital cameras can approach that degree of resolution. Color digital photographs are especially troublesome, since they offer a much narrower range of color compared to traditional, chemically processed film. THE TRUTH IS OFTEN IN THE DETAILS Digital images have less detail than the original impressions. Gustave Flaubert supposedly remarked that God is in the details. In evidence, the truth is often in the details. Fewer details means less exclusionary information. In a criminal investigation, people with freckles can’t be excluded if the photograph of the perpetrator lacks those essential details. Similarly, an image produced by digital technology can sometimes lead an expert to an erroneous conclusion. These criticisms are beginning to hit their mark. In 2004, the Connecticut Supreme Court handed down a decision that demanded a more extensive foundation for digitally enhanced photographs. State v. Swinton, 847 A.2d 921 (Conn. 2004). The photographs in question were enhancements of photographs of bitemarks. The prosecution expert had only a limited knowledge of the computer hardware and software used. According to the court, without a witness who can satisfactorily explain or analyze the data and the program, the effectiveness of cross-examination can be seriously undermined, particularly in light of the extent to which the evidence in the present case has been ‘created.’” There are many common, comforting myths about digitized evidence. However, we must come to grips with the harsh realities: Electronic evidence can be modified, it is vulnerable to hackers, the alteration of electronic evidence is difficult to detect and technicians need additional training in its use. Judges and attorneys alike need to develop a healthy skepticism toward evidence produced by digital technology. Edward J. Imwinkelried has been appointed the Edward L. Barrett Professor of Law at the University of California, Davis School of Law.

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