Law enforcement investigators often rely on some means of preparing a “likeness” of a suspect. The two most popular methods are using the services of a sketch artist or employing one of several different computer programs available on the market today.
Long before the digital age began, the freehand sketching was king. And many highly skilled sketch artists evolved over time, but in the late 1960’s a new method of facial identification came on the scene.
A Brief History of Photo*Fit
A psychologist/amateur photographer calling himself Jacques Penry developed a kit consisting of actual black and white photos that had been cut into individual pieces such as hairlines, eyes, noses, mouths and chins. Penry (his real name was Bill Ryan) convinced the British Home Office of the value of such a kit, since it could be produced rather inexpensively, and many British police departments didn’t have a sketch artist readily available.
The Home Office agreed and gave Penry access to criminal “mugshots” collected from files of Scotland Yard. By the early 1970s, Photo*Fit was a popular police tool throughout the British Isles.
At the time of Penry’s development of Photo-Fit, the only other method of composite construction other than hand-drawn sketches was Smith & Wesson’s Identi-Kit. The development of a “Computerized” Version. Several years later, Penry now approaching the age of 80, decided to sell Photo*Fit to an American company, Sirchie Finger Print Laboratories. Sirchie bought full manufacturing rights and in the mid-1980s, began working on a software version, which they called ComPHOTOfit.
Also during the mid-1980s the Electronic Facial Identification Technique (E-FIT) was developed in Great Britain. Like comPHOTOfit, ir began as a black and white computer program, but eventually evolved into a color version.
The original Sirchie version was in black and white but ComPHOTOfit II + Color switched over to all color components. The company recently released ComPHOTOfit III.[db1]
Any method of gaining an accurate description of a suspect from victims and witnesses has its challenges. In recent years a collection of psychologists and FBI agents developed a method that actually helps to produce better recall. This technique, cognitive interviewing, works like this: The witness/victim is asked to recall the events several hours prior to the crime. The witness is then led hour by hour up to the moment of confrontation.
Here’s How ComPHOTOfit works:
The witness has two visual aids when selecting facial components:
1. A printed manual containing photos of every component in the software and,
2. Is also given the opportunity to see these components on the computer’s monitor.
The software package includes a comprehensive, printed User’s Manual that provides step-by-step instructions for the investigator. The method taught by Sirchie’s technical support group suggests that the first step in building a composite is to get the basic facial outline, namely the forehead (hair) and the chin.
From this point on, and based on the information given by the witness, the investigator begins placing the eyes, nose and mouth. Accessories such as a hat, eyeglasses mustaches and beards may be added as needed.
The software includes a complete set of retouching tools that permit eliminating the “puzzle lines” between the various components and each component can be adjusted for symmetry of skin colors of each component. Scars, moles and other facial characteristics can be added using the retouch tools.
The finished composite may then be used to create a “Wanted Poster.”
ComPHOTOfit still draws from mugshots submitted by police agencies all over the world. And an optional feature permits the individual agencies to pull components from their own mugshot libraries.
Over the intervening years, supplements and updates to the software include male and female Caucasian, black, Latin-American, oriental and middle-eastern (Arabic) features.
Besides being a front line tool in the war against crime, ComPHOTOfit is now in the computer labs of many major colleges and universities that offer criminal justice programs.
From the Journal of Forensic Identification Vol. 53, No. 4, July/August 2003*
Gregory A. Parkinson
State Attorney's Office 15th Judicial Circuit Palm Beach County, FL
Background
Today's understanding of crime scene interpretation, combined with long-term experimentation under similar conditions, allows the investigator to gather, test, and formulate theories of origin based on the factual tests conducted by the investigator. The position of cartridges, cartridge cases, and bullets is just as important to the determination of origin as the position of drops of blood. From their placement, it may be possible to deduce the position of firing, the direction of the shot, and in certain cases, the path of the bullet [1]. The test results often establish or refute claims made by witnesses and suspects.
"Stringing" (i.e., using a string to illustrate) a crime scene in order to determine a point of origin has a historical setting dating back to 1939 [2, 3]. Stringing crime scenes involving shootings where two or more holes are made by one bullet may be feasible to determine the line of fire and the firing position of the shooter. Such determinations are made by sighting through the holes to trace the line of f light back to the source [4].
The determining of trajectory originated in the realm of the firearms examiner. The transition from exclusive use by firearms to other areas of crime scene interpretation began in early 1955 with the pioneer work in blood spatter analysis conducted by Professor Herbert L. MacDonell, who applied the same type of trajectory determination to the new discipline. Professor MacDonell deserves major credit for applying established principles of physics to a new scientific discipline. Geometry applied to ballistics is the same as geometry applied to bloodstains [5].
Expert Opinion
As crime scene investigators, it is possible to track the paths of the bullets; trace their trajectories; and video, diagram, or photograph the results. These are basic interpretations of the scene. Anytime you insert a protrusion rod into a bullet hole to show the trajectory of a bullet, you are rendering an expert opinion as to the direction of travel of the bullet based on your training, knowledge, and prior investigative experience. Once we enter the area of calculation adjustment; correction for angles of drift, drop-off, deflections; and the position of the body when the shooting occurred, we are entering into areas of expertise, which is usually the area of the ballistics examiner [6].
Tools Necessary for Trajectory Determination
Tools necessary for trajectory determination include, but are not limited to, the following:
String (various types can be used)
Adhesive tape (any kind)
Measuring tapes (25 ft and roller tape)
Protractor (clear plastic)
Inclinometer (determines angles and slope)
Compass (any 360E camping type)
Marking pens
Adhesive markers (numerical and alphabetical)
Bubble or torpedo level
Laser pointer
A crime scene presents the investigator with a specific scenario, such as a shooting, where there may be spent casings present along with one or more bullet impact sites. The method of operation will depend on the specific circumstances at the crime scene. However, there are some general guidelines to follow:
Vehicles:
If a vehicle with bullet holes in the windows is involved, swab the interior surrounding the holes for possible gunpowder residue testing. It may become an issue in the future.
Examine the impact site and crater of the glass to visually determine whether the bullet originated from the outside to inbound or from the inside to outbound.
Note the location of spiral fractures to determine which impact was first.
Fiberglass rods or wooden dowels (steel and aluminum may be too heavy for shattered glass) may be inserted into the bullet holes to establish the paths. String can be attached to continue the path, which can later be verified with the use of the laser light beam.
If the hole in the glass is less than two inches in diameter, pass a string through a drinking straw, then attach the string to a small spring that can be inserted through the bullet hole. A common toothpick can then be inserted through the opposite end of the spring and this allows the string to be pulled tight with light tension [7]. The string is then attached to the pole at the appropriate level based on the trajectory and laser light indications.
When the vehicle string placement is complete and the locations, measurements, and horizontal and vertical angles have been measured, the completed product is photographed and charted by diagram. It is important to photograph the vehicle from the horizontal plane and to also photograph the stringed angles from the vertical plane via use of a ladder. The combination of the two views complements the diagram and allows both views to confirm each other.
There are certain environmental conditions to consider when conducting trajectory exams. In the case of a vehicle, tire pressure may be a factor. Measure the pounds of pressure in each tire at the time of the initial forensic examination because tire pressure may leak out after the vehicle has been parked for a long time. A change in tire pressure can affect the results of your determination. (The angle can raise or lower, depending on the impact site and which end of the vehicle loses pressure). Measure the ground and determine whether the scene has a slope and, if so, the degree of the slope.
Buildings:
If the scene is a building structure, similar steps are taken to reconstruct the event. Slightly different tools may be necessary. Tape, nails, hammers, extra poles, and so forth may be employed to accomplish the testing process. Many of the previously described steps are repeated when examining buildings.
Recommended Testing
Once a visual inspection of projectile impact sites has been catalogued by diagram, measurements, and photography (video included), a preliminary test should be conducted by use of the laser beam. This may well provide the investigator with a baseline of information with which to conduct further testing.
The second part of the examination is to attach the string from the impact site outward in the direction from which the projectile was fired. It is beneficial to have a set of PVC upright poles to attach the string to once the angle of impact has been determined. The attachment position is based on the angle backtracked from the impact location and angle. The shooter's relative position and distance from the target can often be determined from this test.
Upon completion of the string attachment and pole placement, it should be double-checked with the laser pointer. Minor adjustments are often made during this review; however, the original test results are confirmed at this time.
Injury Analysis on Live or Dead Subjects
Usually when death has occurred, the measurements are documented by the coroner or medical examiner. Most of the measurements are comprehensive, in so far as the location on the body, the direction of travel, and the final resting place or exit of the bullet. The physical examination of the victim will generally include x-ray photographs showing the location of projectiles within the body. The entrance point of the wound and the subsequent path traveled provide a sound basis for angle determination, unless the path direction is def lected by bone material.
What is rarely seen in medical reports is a measurement based on the victim's reported stance at the time of the shooting, from the bottom of the foot to the entry and exit wounds, an angle determination based on a horizontal and vertical basis. This is nothing more than a combination of an anatomical chart combined with a basic graph or coordinate system.
Another factor to consider is the type of footwear. The thickness of the heel must be factored in and can change the height. When the height is altered, the angle and distance changes (the greater or lesser the angle, the greater or lesser the distance becomes). A quick demonstration can be done with a common protractor. Draw a right angle, extend a line from the base and a second line two or more degrees different, and observe the difference: As the lines get farther apart, the longer the lines become.
Consideration must be given to multiple wounds because the person will most likely be reacting to the threat by rotating, crouching, or moving in some other way for defense posturing or evasion purposes. In the case of deceased victims, ballistic rods are an invaluable tool for showing direction and allow an angle determination from a horizontal and vertical plane. (This form of examination should only be performed under the supervision of, and with permission from, the medical examiner or coroner.)
When examining living persons, verbal descriptions are usually accepted as described; however, the stress of the event often leaves the facts somewhat cloudy. Proper measurements and stringing the scene can often confirm the accuracy of the victim's statement.
Any firearm examinations necessary for the investigation (rifling characteristics, ejector marks, extractor marks, breach face marks, etc.) should be done before any shell ejection testing by the investigator. In cases where the shooter's approximate position is significant (e.g., officer involved shootings), it may be necessary to take similar weapons (i.e., make and model) for testing three areas: the initial distance the shell is ejected; the secondary roll to a final resting place; and the angle at which the ejected shell exited the weapon (taking into consideration types of surfaces, for example, concrete, asphalt, sand, grass, gravel, and so forth). Multiple shots should be fired from each weapon (at least ten shots) to establish a known average of minimum and maximum distances. It will quickly be established that no two casings come out at the same angle, same distance, and same roll; however, there will be a general pattern established.
Problems with String
The use of string presents two challenges that are difficult to overcome. The first problem is the droop factor. String pulled from one point to another will eventually droop because of the weight of the string and the tension on the fibers that make up the string. String is generally attached to the item with some form of tape and is likely to droop while being attached to the second area. The longer the length of string, the more the weight will shift toward the center of gravity, creating the droop factor.
The droop factor is created by the bulk of unsupported material and will seek the center of gravity regardless of the size or length of string used. If the ends are attached at different levels, the center of gravity will shift to the lower end.
A second factor with string is the strength of it. The stronger the string, the larger the diameter of the string. The larger the diameter, the heavier the weight of the string. The heavier the weight, the greater the droop factor. (A new type of nylon string being marketed for use in low light conditions is a reflective string, which reacts well when illuminated with a f lashlight or photo f lash.)
Problems with Laser Light
The laser light beam has certain benefits, such as specificity, because the light beam travels in a straight line at a constant speed of 186,272 miles per second to the target. The drawbacks in using laser light are that it is somewhat difficult to work with in the daytime; it does not provide a complete sequence of beginning, middle, and end (beginning and end only); it is subject to movement by the holder; it is unsteady in windy conditions; and it generally has a short range in bright sunlight conditions (generally works best in dark or night conditions).
Demonstration of a Laser Light Problem
A quick, easy demonstration of trajectory determination is to take a small piece of presentation foam board, carve a groove in it, place the laser in the groove, and tape it in place. Place the board on a f lat surface and mark (with tape) where the light beam strikes, then elevate one corner of your choice, and watch the location difference. This has a dramatic visual effect on observers.
Demonstration in Open Court
The value of a simple demonstration in open court before a jury carries tremendous demonstrative weight, because it transforms the investigator's testimony from verbalization to what becomes a part of the immediate experience of the jury. Having a vertical measurement of the bullet impact, place the protractor on the measurement site, and use the bubble level to level the protractor. Attach the string to the center of the protractor and then run the string out on the angle and direction determined from the crime scene. Attach the end to a pole or microphone stand, double-check your string placement with a laser pointer, and confirm the position. Used properly, the stringing of a crime scene can be compelling demonstrative evidence.
New methods and innovative techniques have their place in the scientific community. The International Association for Identification's annual educational conference is an excellent place where scientists and practitioners meet each year to review, demonstrate, and refine advances in crime scene processing and physical evidence interpretation. Both new and traditional techniques are often taught during the educational conferences. Some are presented as poster presentations, and others are presented in the form of case presentations or lectures before a general session audience. This process of demonstrating new techniques allows the crime scene investigator to gain the opportunity to legitimately employ the techniques described with the support of the general scientific community. The application of relative trajectory determination by use of string in crime scene reconstruction has been demonstrated since 1973 in 58 bloodstain evidence classes offered during the annual International Association for Identification's educational conferences.
LASER TRAJECTORY KIT
Conclusion
The use of string in reconstructing crime scenes for certain types of evidence is a relatively simple, inexpensive, and accurate method of demonstrating trajectory. Caution is emphasized that the determination is not exact but is more of a general, or relative, position fixing method. The use of string is still valid and remains as only one of several methods of determining the point of convergence or origin. When feasible for use in court, it remains an excellent demonstrative tool.
The author would like to thank Professor Herbert L. MacDonell, Dick Rogers of Evi-Paq, Michael Canfield of the E.C.P.I. Company, and William Sampson for their help and technical assistance in preparing this article.
For further information, please contact:
Inv. Gregory A. Parkinson State Attorney's Office, 15th Judicial Circuit Special Investigations Unit 401 N. Dixie Hwy, West Palm Beach, FL 33401 (561) 355-7473
References
Fischer, B. A. J. Techniques of Crime Scene Investigation, 6th ed.; CRC Press: Boca Raton, FL, 2000; p 287.
Bevel, T.; Gardner, R. M. Bloodstain Pattern Analysis, CRC Press: Boca Raton, FL, 1997; p 13.
MacDonnell, H. L., Laboratory of Forensic Science, Corning, N.Y. Personal communication.
Osterberg, J. W.; Ward, R. H. Criminal Investigation: A Method for Reconstructing the Past, 3rd ed.; Anderson Publishing: Cincinnati, OH, 2000, p 79.
MacDonnell, H. L. Flight Characteristics and Stain Patterns of Human Blood; US GPO 0-564-050, National Institute of Law Enforcement and Criminal Justice, US Government Printing Office: Washington, DC, 1974, pp 73-74.
Tomboc, R. C. Using the Trajectory Kit with Trajectory Laser Pointer. Presented at the 79th Annual Conference of the International Association for Identification, Phoenix, AZ, July, 1994.
Sampson, W.; Advanced Crime Scene Techniques. Dade-Metro Training Center, Miami, FL, October, 2000.
*From the Journal of Forensic Identification Vol. 53, No. 4, July/August 2003 The Official Publication of the International Association for Identification "Reproduction of the Journal of Forensic Identification, in whole or in part, for noncommercial, educational use is permitted provided proper citation of the source is noted. Reproduction for any other use is prohibited without prior written permission. Requests for permission may be addressed to the editor (of the Journal of Forensic Identification -- [email protected])."
The following was extracted from an article published on www.clpex.com
Written & Compiled By: Thomas J. Ferriola Identification Technician Sebastian Police Department, Florida
Level One ( Ridge Flow & Class Characteristics) is the largest scale of information, such as the general type of the central area of the fingerprint, such as an arch, whorl, or loop. Other level one details may include such matters as the overall ridge count, focal areas of the print, such as "delta regions" (roughly triangular shaped areas where ridges flowing in different directions meet), and the orientation of the print. Showing that level one details are identical is not enough to make an identification of the finger that is the source of a latent print. Level Two (Ridge Characteristics or Points)detail focuses on the characteristics of ridge paths, such as places where ridges bifurcate or end or create dots or islands. These features provide a great deal of detail. Each feature can be identified in terms of the type of feature (end, bifurcation, etc.), its direction, and its location with respect to other identifiable features in the print. Level two detail can be used to identify one individual finger from among the entire human population as the source of the latent print. Level Three ( Ridge Structure ) detail can be described as "ridge detail," with such tiny features as pores on a ridge and the width and shape of the ridge itself and its edges. These level three details are the most vulnerable to problems with the quality of the latent print. They are so small that a clear, high quality image is needed to make accurate comparisons. When the latent print is sufficiently clear, level three detail can contribute to the identification of the source of a latent print.
The Justice Department, FBI uses and has adopted a standard method afingerprint examiner goes through. It is a four-step process with the acronym "ACE-V," for analysis, comparison, evaluation, and verification, and focusing on Level one, Level two and Level three details The first phase is analysis. Analysis is a thorough examination of the unknown. In the case of fingerprints, the latent print would be examined to determine the ridge formations that exist at three levels of detail. “Level one detail” refers to the first appearance of the print noticed at the beginning of an examination. Generally, “Level one” refers to the overall pattern or ridge flow tendencies of the print. “Level two detail” refers to the next features observed, generally those with a physical dimension on the order of magnitude of a ridge width. The so--called “Minutiae” or “points,” are level two detail. “Level three detail” refers to smaller features generally observed under magnification. Level three features are normally contained within a single ridge, such as shapes and positions of sweat pores (poroscopy) or distinctive shapes on the edge of a ridge (edgeoscopy). Incipient ridge shapes are also usually considered level three details, but the presence of incipient ridges in general would be a level one consideration. A large scar might be considered as level one detail, whereas a small scar might only be observed at level two. Within a scar there may be valuable level three detail. A thorough analysis of the unknown consists of far more than simply looking at the minutiae points.
Another part of the analysis of a latent print is the assessment of all of the various causes of distortion and their effect upon the print. Distortion could result from a number of sources, including the matrix, or residue, which comprises the print; the substrate, or surface, on which the print was left; the direction of touch; the pressure of the touch; reaction of the matrix with the development medium; and so on. All of these factors should be assessed during the analysis of the latent print.
Analysis also takes into consideration the clarity of the print. Clarity differences result from distortion. A latent print lacking level three detail as a result of pressure distortion, for example, might be described as having a low degree of clarity, whereas a print showing good pore and edge structure and having minimal distortion might be characterized as having a high degree of clarity.
Inherent in the analysis of the latent print is the selection of a suitable target to be memorized and used when searching the inked prints. Such a target is usually an easily recognizable cluster of minutiae points. On the other hand, it might be a distinctive scar, a prominent crease or wrinkle pattern, or any other significant and easily recognizable formation that results from features in the area of friction skin that left the print. The target will be the starting point for the second and third phases of the identification process, therefore it should be both an easily recognizable feature in the unknown print and potentially the easiest to find in the known prints.
A thorough analysis should be accompanied by the taking of detailed notes describing the latent print. Notes should make reference to all observed distortion factors. Notes may also include reference to the level of clarity present in the print. One might actually draw the target, both as an aid in its memorization and as a part of the description of the latent. On occasion, one may even choose to physically follow or trace the ridges completely throughout the print and draw a representation of the entire latent in the notes. This type of demonstrable analysis lends credence to any subsequent identification.
Once a thorough analysis of the latent print has been completed, the second phase of theidentification process is comparison. Whereas, during analysis the examiner focuses exclusively on the unknown print, during the comparison phase the examiner concentrates primarily on the known, or inked, prints. The examiner searches each inked print in turn, observing all three levels of detail in a search for an image that is consistent with the detail found in the latent print during its analysis, and that has the target selected for the search.
Once a known print is located that is consistent in appearance with the unknown and contains the target, the examiner enters the third phase of the identification process, evaluation. In this phase, the two prints are examined together, side by side. The examiner finds features first in the unknown print, then in the known print, then evaluates the corresponding features to determine if they are within tolerance for the level of clarity that exists in the images. In this manner, the examiner goes back and forth between the two prints, finding features first in the unknown, then evaluating their appearance in the known print.
The reason for working from the unknown image to the known has its foundation in human psychology. When dealing with a less clear image, usually the latent or unknown print, the brain is subject to influence by “mind--set.” If a feature is first observed in a clear image, the brain may form an expectation and be tricked into “seeing” the same feature in an unclear image even though it does not actually exist there. Take, for example, in the case of a faint ninhydrin print ( a chemical used in latent print development ) in which the ridges appear primarily as a series of light dots. If the examiner concentrates on first finding points in a clear, high contrast inked print, then tries to find the same points in the poorly defined latent, mind--set might easily lead the examiner to “see” points that do not exist. To avoid this possibility, a cautious examiner always finds the features in the unknown print first, free from mind--set, then locates and evaluates the corresponding features in the known print.
During the evaluation phase of the identification process, the examiner must consider all of the differences in appearance between the two images. It is an accepted tenant of fingerprint science that no two prints will ever be exactly the same in all respects. First, any touch is a contact between a complex curved surface (the skin) and, usually, a flat surface.
This touch must necessarily be accompanied by distortion of the skin itself. Second, the amount and type of matrix (residue left behind) will differ. Third, the angle and pressure of the contact will change from one touch to the next. Fourth, the size of the area of skin coming into contact with the surface will vary. Any number of other factors may also contribute to differences, some subtle and some extreme, in the appearance of two prints that result from two touches by the same region of friction skin. It is not sufficient to look only for similarities and ignore the differences, nor is it proper to look at only some features and ignore others. The true expert must consider everything appearing in each image.
It is at this point that tolerance enters the equation. Based on an understanding of distortion and its sources, some differences in appearance fall within acceptable limits of tolerance. For example, it is an easy task to understand and to account for the differences in appearance between a print resulting from a light touch and a print resulting from a heavy touch. The differences in appearance between a fully rolled inked print and a crime scene mark are also easy to understand and easy to account for. These differences would be said to be within tolerance.
On the other hand, for example, a clear crime scene mark with a whorl pattern having an outer tracing, when compared to an inked print having a whorl pattern with an inner tracing, would be considered out of tolerance, even at level one. A ridge ending or bifurcation in one print where an open field of ridges exists in the other print would be out of tolerance at level two. Two bifurcations opening in the same direction, whose shoulders are essentially even in a crime scene mark with high clarity, would also be out of tolerance when evaluated with two bifurcations opening in the same direction in the inked print in which the shoulders were offset.
Analysis, comparison, and evaluation – ACE – takes into consideration much more than simply looking at the points in a crime scene mark, checking the inked print, and counting until a threshold number is reached. It is the evaluation, that is, the determination that all features are within tolerance as determined by the clarity of the two images, that sets the scientific process apart from the simpler idea of counting points. For that reason, this methodology is sometimes referred to as the “evaluative process.”
The final step in the process is verification the general rule is that all positive identification opinions must be verified by a second qualified expert. The second expert may repeat the entire process, but the comparison may not be blind. That is, the second expert may know from the outset that another examiner has already made the positive identification.
Some organizations do not tell the latent print examiner conducting the verification the results of their examination.
Technically speaking, verification is not a part of the identification process. The identification itself takes place in the mind of the examiner making the comparison. Verification is the identification process repeated in someone else's mind.
Independent verification, however, is a crucial part of the scientific process. Without such verification, identification has not been proven to the level required by science. No report should be made of an identification until a second qualified expert has made that verification independently of influence or pressure from any source.
Of course, the most important practical reason for having verification performed is that it reduces the risk of an erroneous identification being reported. In any field of human endeavor, there exists the potential for human error. When an erroneous identification is formally reported, almost certainly an innocent person will suffer. A conscientious program of independent verification, followed without exception, should catch erroneous identifications and prevent them from being acted upon.
Erroneous identifications among cautious, competent examiners, thankfully, are exceedingly rare; some might say, “impossible.” Clerical errors, however, are not uncommon. Writing down the wrong finger, or worse, writing down the wrong name, occurs far more frequently than a true erroneous identification.
If the most important practical function of verification is to prevent the reporting of erroneous identifications, the more frequent benefit of verification is the avoidance of embarrassment, or worse, false arrest resulting from clerical errors. A true clerical error should not be considered an erroneous identification, but department policies and procedures should be written to ensure the prevention of clerical errors.
From a talk by: Barbara Tversky, Professor of Psychology and George Fisher, Professor of Law
Laura Engelhardt
Stanford Law School, April 5, 1999. In a presentation sponsored by the Stanford Journal of Legal Studies, George Fisher placed Barbara Tversky’s research on memory fallibility into the context of police investigations and jury verdicts, discussing the relevance of such research to our system of justice.
The bedrock of the American judicial process is the honesty of witnesses in trial. Eyewitness testimony can make a deep impression on a jury, which is often exclusively assigned the role of sorting out credibility issues and making judgments about the truth of witness statements. Perjury is a crime, because lying under oath can subvert the integrity of a trial and the legitimacy of the judicial system. However, perjury is defined as knowingly making a false statement—merely misremembering is not a crime. Moreover, the jury makes its determinations of witness credibility and veracity in secret, without revealing the reason for its final judgment.
Recognizing the fallibility of witness memories, then, is especially important to participants in the judicial process, since many trials revolve around factual determinations of whom to believe. Rarely will a factual question result in a successful appeal—effectively giving many parties only one chance at justice. Arriving at a just result and a correct determination of truth is difficult enough without the added possibility that witnesses themselves may not be aware of inaccuracies in their testimony.
Several studies have been conducted on human memory and on subjects’ propensity to remember erroneously events and details that did not occur. Elizabeth Loftus performed experiments in the mid-seventies demonstrating the effect of a third party’s introducing false facts into memory. Subjects were shown a slide of a car at an intersection with either a yield sign or a stop sign. Experimenters asked participants questions, falsely introducing the term "stop sign" into the question instead of referring to the yield sign participants had actually seen.
Similarly, experimenters falsely substituted the term "yield sign" in questions directed to participants who had actually seen the stop sign slide. The results indicated that subjects remembered seeing the false image. In the initial part of the experiment, subjects also viewed a slide showing a car accident. Some subjects were later asked how fast the cars were traveling when they "hit" each other, others were asked how fast the cars were traveling when they "smashed" into each other. Those subjects questioned using the word "smashed" were more likely to report having seen broken glass in the original slide. The introduction of false cues altered participants’ memories.
Courts, lawyers and police officers are now aware of the ability of third parties to introduce false memories to witnesses. For this reason, lawyers closely question witnesses regarding the accuracy of their memories and about any possible "assistance" from others in the formation of their present memories. However, psychologists have long recognized that gap filling and reliance on assumptions are necessary to function in our society. For example, if we did not assume that mail will be delivered or that the supermarkets will continue to stock bread, we would behave quite differently than we do.
We are constantly filling in the gaps in our recollection and interpreting things we hear. For instance, while on the subway we might hear garbled words like "next," "transfer," and "train." Building on our assumptions and knowledge, we may put together the actual statement: "Next stop 53rd Street, transfer available to the E train." Indeed, we may even remember having heard the full statement.
So what is an "original memory?" The process of interpretation occurs at the very formation of memory—thus introducing distortion from the beginning. Furthermore, witnesses can distort their own memories without the help of examiners, police officers or lawyers. Rarely do we tell a story or recount events without a purpose. Every act of telling and retelling is tailored to a particular listener; we would not expect someone to listen to every detail of our morning commute, so we edit out extraneous material. The act of telling a story adds another layer of distortion, which in turn affects the underlying memory of the event. This is why a fish story, which grows with each retelling, can eventually lead the teller to believe it.
Once witnesses state facts in a particular way or identify a particular person as the perpetrator, they are unwilling or even unable—due to the reconstruction of their memory—to reconsider their initial understanding. When a witness identifies a person in a line-up, he is likely to identify that same person in later line-ups, even when the person identified is not the perpetrator. Although juries and decision-makers place great reliance on eyewitness identification, they are often unaware of the danger of false memories.
Experiments conducted by Barbara Tversky and Elizabeth Marsh corroborate the vulnerability of human memory to bias.In one group of studies, participants were given the "Roommate Story," a description of incidents involving his or her two fictitious roommates. The incidents were categorized as annoying, neutral, or socially "cool." Later, participants were asked to neutrally recount the incidents with one roommate, to write a letter of recommendation for one roommate’s application to a fraternity or sorority, or to write a letter to the office of student housing requesting the removal of one of the roommates.
When later asked to recount the original story, participants who had written biased letters recalled more of the annoying or "cool" incidents associated with their letters. They also included more elaborations consistent with their bias. These participants made judgments based upon the annoying or social events they discussed in their letters. Neutral participants made few elaborations, and they also made fewer errors in their retelling, such as attributing events to the wrong roommate. The study also showed that participants writing biased letters recalled more biased information for the character they wrote about, whereas the other roommate was viewed neutrally.
Memory is affected by retelling, and we rarely tell a story in a neutral fashion. By tailoring our stories to our listeners, our bias distorts the very formation of memory—even without the introduction of misinformation by a third party. The protections of the judicial system against prosecutors and police "assisting" a witness’ memory may not sufficiently ensure the accuracy of those memories. Even though prosecutors refrain from "refreshing" witness A’s memory by showing her witness B’s testimony, the mere act of telling prosecutors what happened may bias and distort the witness’s memory. Eyewitness testimony, then, is innately suspect.
Lawyers place great import on testimony by the other side’s witness that favors their own side’s case. For example, defense attorneys make much of prosecution witnesses’ recollection of exonerating details. In light of psychological studies demonstrating the effect of bias on memory, the reliance and weight placed on such "admissions" may be appropriate, since witnesses are more apt to tailor their stories—and thus their memories—to the interests of the first listeners.
An eyewitness to a crime is more inclined to recount, and thus remember incriminating details, when speaking to a police officer intent on solving the crime. If later the eyewitness still remembers details that throw doubt on the culpability of the suspect, such doubts should hold greater weight than the remembrance of incriminating details.
In another part of the Tversky-Marsh study, participants were asked to play prosecutors presenting a summation to the jury. Participants first read a murder story, where two men were suspects. Participants were then asked either to prepare a neutral recounting of all they remembered about one suspect, or to prepare a summation to the jury about one suspect. Later, participants were asked to recall the original story. Participants who wrote summations recalled more incriminating details and wrongly attributed details among suspects more often than participants who originally wrote a neutral recounting.
Bias creeps into memory without our knowledge, without our awareness. While confidence and accuracy are generally correlated, when misleading information is given, witness confidence is often higher for the incorrect information than for the correct information. This leads many to question the competence of the average person to determine credibility issues. Juries are the fact-finders, and credibility issues are to be determined by juries.
The issue then arises whether juries are equipped to make these determinations. Expert testimony may not be helpful. Indeed, since the very act of forming a memory creates distortion, how can anyone uncover the "truth" behind a person’s statements? Perhaps it is the terrible truth that in many cases we are simply not capable of determining what happened, yet are duty-bound to so determine. Maybe this is why we cling to the sanctity of the jury and the secrecy of jury findings:
We can put such questions before the jury entirely without fear of embarrassment, because the way the jury resolves the questions and, in all likelihood, the soundness of its answers will remain forever hidden. Perhaps the allure of the black box as a means toward apparent certainty in an uncertain world has tempted us to entrust the jury with more and harder questions than it has the power to answer.
The courts’ reliance on witnesses is built into the common-law judicial system, a reliance that is placed in check by the opposing counsel’s right to cross-examination—an important component of the adversarial legal process—and the law’s trust of the jury’s common sense. The fixation on witnesses reflects the weight given to personal testimony. As shown by recent studies, this weight must be balanced by an awareness that it is not necessary for a witness to lie or be coaxed by prosecutorial error to inaccurately state the facts—the mere fault of being human results in distorted memory and inaccurate testimony.