W. Jerry Chisum, BS¹; Brent E. Turvey, MS²

Title: "Evidence Dynamics: Locard's Exchange Principle & Crime Reconstruction"

Reference: Chisum, W.J., & Turvey, B. "Evidence Dynamics: Locard's Exchange Principle & Crime Reconstruction," Journal of Behavioral Profiling, January, 2000, Vol. 1, No. 1

Abstract: Conclusions regarding the circumstances and behaviors elicited from the physical evidence related to a crime (crime reconstruction) can infrequently be housed within the confines of absolute certainty. This paper discusses the development of Locard's Exchange Principle and historical and contemporary philosophies surrounding crime reconstruction. It further discusses the fallacy of assuming the integrity of physical evidence, and provides a logical foundation for the concept of Evidence Dynamics. Evidence Dynamics refers to any influence that changes, relocates, obscures, or obliterates physical evidence, regardless of intent. Evidence Dynamics, it is further argued, come into play during the interval that begins as evidence is being transferred, and ends when the case is ultimately adjudicated. A discussion of the various types of Evidence Dynamics is provided, followed up by demonstrative examples from the authors' case files.

¹W. Jerry Chisum has been a criminalist since 1960. In October of 1998, he retired from 30 years of service with the California Department of Justice into private practice. He is currently serving as Vice-President of the Academy of Behavioral Profiling, and is a member of their Board of Directors. He can be reached for comment or consultation by contacting: URL: www.ncit.com; jchisum@profiling.org

²Brent E. Turvey, MS is a forensic scientist, criminal profiler, and a full partner of Knowledge Solutions, LLC. He is currently serving as Secretary of the Academy of Behavioral Profiling, and is a member of their Board of Directors. He can be reached for comment, consultation or reprints of this article by contacting: Knowledge Solutions, 1961 Main St., PMB 221, Watsonville, CA 95076; Phone (831)786-9238; bturvey@corpus-delicti.com.

Of all responsibilities shouldered by the forensic scientist, the reconstruction of the circumstances and behaviors involved in a crime is one of the most important. In conjunction with agreeable witness accounts, a crime reconstruction may be a powerful instrument of corroboration. In the face of conflicted witness accounts, it may provide an objective view that points to one possibility over another. In the absence of witness accounts, it may be used to investigate and establish the actions that occurred at the scene of a crime. The role that crime reconstruction can play investigatively and legally should never be underestimated.

Because of the varied evidence and circumstances involved, the ability to reconstruct crime requires broad forensic knowledge, an objective if not conservative disposition towards the examination and interpretation of evidence, and what the fictional Dr. Watson of Sherlock Holmes fame referred to as a "peculiar facility for deduction." [9]

Despite its importance to investigative and legal venues, crime reconstruction is often performed inappropriately by the unknowledgeable and overconfident. This includes those with little knowledge of, or training in, the peculiarities of physical evidence and the forensic sciences. Those testifying as experts in the area of crime reconstruction routinely cite as a premise, for otherwise unproven opinions, the sum of their education, training, and experience. It may be the case that this is offered in the place of facts from the case file. This practice is regarded as illegitimate for a forensic examiner. "Experience should not make the expert less responsible, but rather more responsible for justifying an opinion with defensible scientific facts." [12]

Conclusions regarding the circumstances and behaviors elicited from the physical evidence related to a crime can infrequently be housed within the confines of absolute certainty. It is often an intensive process with imprecise results containing evidentiary holes, sequential gaps, and alternate possibilities. This does not suggest that crime reconstruction efforts lack investigative or legal utility. The utility of crime reconstruction is by no means bound to any predisposition for certainty. Rather, its utility is more often found in establishing the general circumstances of a crime, demonstrating links between victims, suspects, and offenders, corroboration of witness statements, providing investigative leads, and identifying potential suspects. [8]

Further still, it is often the case that what the physical evidence excludes, fails to establish, or equivocates, is actually of great investigative and legal importance. Forensic analysis in general, and crime reconstruction in particular, is concerned with those conclusions that can be logically drawn from the evidence, as well as with those that cannot. As such, the consideration of both the strengths and limitations of available physical evidence are an important part of crime reconstruction. It is with these considerations in mind that we begin our discussion of the relationship between Locard's Exchange Principle, Crime Reconstruction, Evidence Dynamics and their implications to forensic examinations.

The Development of Locard's Exchange Principle
Alphonse Bertillon developed one of the first scientific systems of documenting personal identification in Paris in the late 1800s [3, 11]. In 1879, Msr. Bertillon began his career when he was appointed clerk in the Premier Bureau of the Prefecture of Police [10]. The sheer volume of the files required organization. He used the measurement system that his father, a physical anthropologist, used to organize skeletal material. Bertillon’s genius was in adapting this method to living persons and establishing a record system. The method referred to ultimately as Bertillonage used the relatively simple procedure of taking a series of body measurements, noting other physical characteristics, and placing this information on a single identification card in a police file [3]. As the method developed he started adding photographs of the individual to the files. Bertillonage was a significant advancement in terms of providing a useful database of criminals for criminal investigators.

Bertillon was motivated to develop his methods not only by the desire to assist in the tracking of criminals and their behavior, but also by a personal belief that everything that "lived and moved under heaven" was somehow unique [10]. His was something of a radical notion in criminal investigation at the time: that science and logic should be used to investigate and solve crime. As Msr. Bertillon's biographer stated:

The methods of the French police in that year of grace 1879 had changed very little in principle from those initiated by that criminal turned policeman, the brilliant and unscrupulous [Eugene] Vidocq. They consisted in the liberal use of the police informer, and agent provocateur. [10]

Bertillonage was employed to identify criminals by law enforcement for at least two decades, until it was replaced by the use of fingerprints. In 1891, Dr. Hans Gross, an Austrian Magistrate and Professor of Criminology, made the following observation, "The advantages of finger-prints over the Bertillon system have become so well established that the latter can with perfect safety be dispensed with altogether as unnecessary for the purposes of identification."[5]

However, Bertillonage was not the limit of Msr. Bertillon's contribution to the forensic sciences, nor was it his most significant. His dedication to precise measurements and the use of photography led to a combination of the two practices beyond criminal identification. Bertillon assisted in the development and practice of forensic photography by introducing a measuring scale with the persons and objects of evidence that he photographed [10]. The usefulness of this practice soon became apparent. He was routinely sent out with investigators to document crime scenes. He would photograph the bodies of victims, their relationship to significant items of evidence in the scene, as well as the position, size, nature and extent of other physical evidence including footprints, stains, toolmarks, and points of entry [10]. Until the development of this practice, criminal investigators and the courts relied upon sketches and notes of varying precision for their understanding of the context of a crime. That is, if any record were made of a crime scene at all.

Bertillon also instructed and influenced several students, including Dr. Edmond Locard, whose work formed the basis for what is widely regarded as a cornerstone of the forensic sciences, Locard's Exchange Principle (for discussion, see: [3], [6] & [11]). Dr. Locard, like Dr. Hans Gross and Msr. Bertillon before him, advocated the application of scientific methods and logic to criminal investigation and identification [11]. As stated by Dr. John Thornton, a criminalist and a former professor of forensic science at the University of California, Berkeley:

Forensic scientists have almost universally accepted the Locard Exchange Principle. This doctrine was enunciated early in the 20th Century by Edmund Locard, the director of the first crime laboratory, in Lyon, France. Locard's Exchange Principle states that with contact between two items, there will be an exchange… [12]

Due in no small part to Mr. Bertillon's influence, it was Dr. Locard's belief and assertion that when any person comes into contact with an object or another person, a cross-transfer of physical evidence occurs [11]. By recognizing, documenting, and examining the nature and extent of this evidentiary exchange, Locard observed that criminals could be associated with particular locations, items of evidence and victims. The detection of the exchanged materials is interpreted to mean that the two objects were in contact. This is the cause and effect principle reversed; the effect is observed and the cause is concluded.

Forensic scientists also recognize that the nature and extent of this exchange can be used not only to associate a criminal with locations, items, and victims, but with specific actions as well [2, 3, 11, 13, 14].

Crime Reconstruction
Crime reconstruction is "the determination of the actions surrounding the commission of a crime." [1] Careful and competent examination of the physical evidence the documentation of the crime scene allows for this determination. The systematic documentation and recording of the crime scene is required for this analysis. The photographic documentation as established by Bertillon is a necessity for crime reconstruction. The veracity of statements by witnesses, victims, and suspects can be established by reconstruction.

Modern methods of crime reconstruction owe themselves to a strong history marked by rigorous analytical thought and forensic application. The collective work of Alphonse Bertillon, Dr. Hans Gross, and Dr. Edmond Locard are no small part of this history. Enduring themes include the importance of physical evidence, objectivity, the necessary employment of logic, and viewing witness, victim, and offender statements with suspicion.

Just before the turn of the century, Dr. Hans Gross, in discussing how a crime should be reconstructed, argued for strict objectivity and a logical, sequential, frame by frame analysis on the part of criminal investigators:

Nothing can be known if nothing has happened…

…in the profession of the criminal expert everything bearing the least trace of exaggeration must be removed in the most energetic and conscientious manner; otherwise, the Investigating Officer will become an expert unworthy of his service and even dangerous to humanity.

…all of the circumstances of the crime must be clearly taken into account and submitted to a strict logical examination from their commencement to their last stage. If at a given moment something has not been explained, suspicion is justified and a pause must be made at the point where the logical sequence is broken...[5].

Dr. Gross also decried the heavy reliance of criminal investigators and the courts on witness accounts, strongly advocating the use of physical evidence, writing:

The progress of criminology means less trust in witnesses and more in real proofs. [9]

Dr. Edmond Locard, in speaking similarly on the subject of physical evidence and crime reconstruction, maintained that:

… the criminologist re-creates the criminal from traces the latter leaves behind, just as the archaeologist reconstructs prehistoric beings from his finds. [9]

Dr. Theodore Reik, a Professor of Psychoanalysis at Vienna University, an early disciple of Dr. Sigmund Freud, also argued for the use of objectivity and logic in the investigation of crime and criminals:

The object of the criminologist's reasoning is knowledge of a material event and the finding of an unknown person…

Cool, objective thought, re-examination of facts according to the rules of logic, raisonnement (Locard) is the pivot of the detectives mental process. [9]

In the second half of this century, the late Dr. Paul Kirk, Professor of Criminalistics at the University of California, Berkeley, shared the views of Drs. Gross and Locard regarding issues of witnesses, physical evidence, and crime reconstruction, arguing:

…the utilization of physical evidence is critical to the solution of most crime. No longer may the police depend upon the confession, as they have done to a large extent in the past. The eyewitness has never been dependable, as any experienced investigator or attorney knows quite well. Only physical evidence is infallible, and then only when it is properly recognized, studied, and interpreted. [13]

Dr. Kirk further argued, supporting the validity of Locard's Exchange Principle, the importance of transfer evidence to crime reconstruction:

Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothing, 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. [13]

However, Dr. Kirk also argued for caution in the interpretation of evidentiary exchanges. In this brief discussion on establishing the identification of an object's source, he makes it clear that it is an endeavor with inherent hazards under even the best conditions.

In the examination and interpretation of physical evidence, the distinction between identification and individuation must always be clearly made, to facilitate the real purpose of the criminalist: to determine the identity of source. That is, two items of evidence, one known and the other unknown, must be identified as having a common origin. On the witness stand, the criminalist must be willing to admit that absolute identity is impossible to establish. Identity of source, on the other hand, often may be established unequivocally, and no witness who has established it need ever back down in the face of cross-examination.

It is precisely here that the greatest caution must be exercised. The inept or biased witness may readily testify to an identity, or to a type of identity, that does not actually exist. This can come about because of his confusion as to the nature of identity, his inability to evaluate the results of his observations, or because his general technical deficiencies preclude meaningful results. [13]

Dr. Henry Lee, former Director of the Connecticut State Police Crime Laboratory, also advocates a combination of both physical evidence and logic by forensic scientists engaging in reconstruction:

Reconstruction not only involves the scientific scene analysis, interpretation of scene pattern evidence and laboratory examination of physical evidence, but also involves systematic study of related information and the logical formulation of a theory. [7]

Dr. John Thornton, previously mentioned, a student of Dr. Kirk, describes the mechanics of the logic that should be employed by forensic scientists when undertaking a forensic examination:

Induction is a type of inference that proceeds from a set of specific observations to a generalization, called a premise. This premise is a working assumption, but it may not always be valid. A deduction, on the other hand, proceeds from a generalization to a specific case, and that is generally what happens in forensic practice. Providing that the premise is valid, the deduction will be valid. But knowing whether the premise is valid is the name of the game here; it is not difficult to be fooled into thinking that one's premises are valid when they are not.

Forensic scientists have, for the most part, treated induction and deduction rather casually. They have failed to recognize that induction, not deduction, is the counterpart of hypothesis testing and theory revision. …too often a hypothesis is declared as a deductive conclusion, when in fact it is a statement awaiting verification through testing. [12]

Criminalist Dr. Richard Saferstein, retired Chief Forensic Scientist from the New Jersey State Police Lab, also argues:

The physical evidence left behind at the crime scene plays a crucial role in reconstructing the events that took place surrounding the crime… The collection and documentation of physical evidence is the foundation of a reconstruction. [11]

One of the authors, also a student of Dr. Kirk, makes a cogent forensic argument regarding the potential value of crime reconstruction to the court in terms of establishing what has actually happened in a given case:

The prosecutor seeks to convict the defendant by making the crime more heinous in nature. The defense seeks to exonerate the defendant. Both theorize about how the crime occurred with different objectives. Both cannot be correct and, lacking a reconstruction, both are probably wrong. The theories are alternatives and should be examined against the evidence…

Any theory of the crime must be based on logic – explaining the physical evidence and its location at the scene. It is through such analysis that the behavior of the perpetrator is revealed...[1]

Crime reconstruction, as argued, involves examining the available physical evidence, those materials left at or removed from the scene, victim, or offender. These materials are used by the forensic scientist establish to contact between the suspect and victim or scene

according to the principle proposed Dr. Locard. These forensically established contacts are then considered in light of available and reliable witness, victim, and offender statements. From this, theories regarding the circumstances of the crime can be generated and falsified by logically applying the information of the established facts of the case. Left standing, ideally, will be legitimate, logical conclusions regarding the actions surrounding the commission of the crime or as put by the fictional Sherlock Holmes in the Sign of Four, "—when you have eliminated the impossible, whatever remains, however improbable, must be the truth."

The Assumption of Integrity
The process of crime reconstruction is often built on the assumption that evidence left behind at a crime scene, which has been recognized, documented, collected, identified, compared, individuated, and reconstructed, is pristine. This assumption involves the belief that the process of taping off an area, limiting access, and setting about the task of taking pictures and making measurements ensures the integrity of the evidence found within. Subsequently, any conclusions reached through forensic examinations and reconstructions of that evidence are assumed to be a reliable lens through which to view the crime. This assumption is not always accurate.

Even though a reliable chain of evidence may be established¹, physical evidence may have been altered prior to or during its collection and examination. Unless the integrity of the evidence can be reliably established, and legitimate evidentiary influences accounted for, the documentation of a chain of evidence, by itself, does not provide acceptable ground upon which to build reliable forensic conclusions.

Consideration of evidentiary influences, or Evidence Dynamics, is a necessary part of the crime reconstruction process.

Evidence Dynamics
Crime reconstruction efforts are concerned with examining the effects or results of actions done in the commission of the crime. As Dr. Gross was fond of saying, "What is effect and what is cause?" [9] This is answered by the use of logic and forensic axioms such as Locard's Exchange Principle. However, often missing from that analysis is a consideration of those influences that can change physical evidence prior to or as a result of its examination.

The general term Evidence Dynamics has been developed by the authors to refer to any influence that changes, relocates, obscures, or obliterates physical evidence, regardless of intent. Evidence Dynamics comes into play during the interval that begins as evidence is being transferred, and ends when the case is ultimately adjudicated. For those who are familiar with such evidentiary influences, and account for them in their analysis, this terminology is intended to provide a necessary and useful descriptor. An appreciation of Evidence Dynamics on what can be concluded from the physical evidence is requisite, and often pivotal, to the reconstruction process.

In the interpretation of Evidence Dynamics, two questions require attention. First, is there an item of evidence that has been demonstrably influenced between the time of the crime and the time of examination? If an item of evidence has been moved, changed, or obscured, then this must be factored into the examiner's analysis in terms of when and how. Second, is there evidence of a circumstance that could have obliterated or influenced evidence? Forensic scientists can only include in their analyses those things for which evidence exists. However, if there is no reasonable suggestion of circumstances that could have influenced or obliterated evidence, then the examiner should not assume that they occurred.

There are many possible influences on Evidence Dynamics that should be considered as evidence is examined. A brief list, not meant to be all-inclusive, is provided below.

Offender actions: The actions of an offender during the commission of their crime and the post-offense interval influence the nature and quality of evidence that is left behind.

These can include Precautionary Acts, Ritual or Fantasy, and Staging. Precautionary Acts involving physical evidence are behaviors committed by an offender before, during, or after an offense that are consciously intended to confuse, hamper, or defeat investigative or forensic efforts for the purposes of concealing their identity, their connection to the crime, or the crime itself [15]. Staging of the crime scene is a specific type of precautionary act that is done to deflect suspicion away from the offender. Staging often involves the addition of, removal of, and manipulation of objects in the crime scene to change the apparent "motive" of the crime. [15] Ritual or Fantasy may also influence the offender’s actions during a crime, and can include such things as postmortem mutilation, necrophilia, and purposeful arrangement of a body or items in a scene. [15]

Victim actions: The victim’s activities prior to a crime may result in artifacts that are mistaken for evidence. The actions of a victim during an attack and in the post-offense interval can influence the nature and quality of evidence that is left behind. This includes defensive actions, such as struggling, fighting, and running, which can relocate transfer evidence, causing secondary transfer. The victim’s actions may also include cleaning up a location or their person after an attack.

Secondary Transfer: Transfer evidence, as we have established, is produced by contact between persons and objects [2, 8]. Secondary transfer refers to an exchange of evidence between objects or persons that occurs subsequent to an original exchange, unassociated with the circumstances that produced the original exchange².

Witnesses: The actions of witnesses in the post-offense interval can influence the nature and quality of evidence that is left behind. This includes actions taken to preserve victim dignity, as well as the deliberate theft of items from the scene upon discovery of an incapacitated or deceased victim.

Weather/ Climate: The weather or climate of a crime can influence the nature and quality of all manner of evidence that is left behind. This includes the destruction or obliteration of evidence by all manner of weather, as well as the effects of weather and climate on rates of body and biological transfer evidence decomposition.

Decomposition: Naturally occurring rates of decomposition, over time, can obscure, obliterate or mimic evidence of injury to a body. The clothing from a decomposed body will normally receive less attention for trace or transfer evidence.

Insect Activity: The actions of flies, ants, beetles, and other insects can obliterate the wounds on a body. They may also move, remove or destroy the transfer evidence.

Animal Predation: The feeding activities of all manner of indigenous wildlife from mice to coyotes and bears can relocate evidence, obliterate patterns, and further obscure, obliterate or mimic evidence of criminal injury to a body.

Fire: In cases were fire is involved, intentional or otherwise, the result can be the obscuring of all manner of physical evidence related to criminal activities, as well as its potential destruction. The evidence showing the actions of the offender regarding the primary offense are obscured if not eliminated by the subsequent arson. Evidence of the arson may remain.

Fire Suppression Efforts: In cases were fire is involved, there may be suppression efforts made. These efforts typically involve the use of high-pressure water, heavy hoses, perhaps chemicals, and firemen. Any of these, alone or in concert, can relocate the evidence, obliterate patterns, cause potentially misleading transfers, and/or add artifact-evidence³, to the scene.

Police: The duty of the first officer on the scene is to protect life, not to preserve evidence. They must establish that the scene is secure from further attacks. Their actions may relocate evidence, obliterate patterns, cause transfers, and add artifact-evidence to the scene.

Emergency Medical Technicians: The actions of emergency medical personnel engaged in life saving activities in a crime may relocate evidence, obliterate patterns, cause transfers, and add artifacts mistaken as evidence. As well, they can add therapeutic injuries to the victim.

Scene Technicians: The actions of technicians working in the physical evidence recognition, preservation, documentation, and collection phases in a crime scene are expected to remove evidence without obliterating patterns, causing potentially misleading transfers, and adding artifact-evidence to the scene. The technicians must thoroughly document the scene prior to entering so the changes that occur are obvious.

Forensic Scientists: The actions of forensic scientists will also remove evidence, obliterate patterns, may cause potentially misleading transfers, and add artifact-evidence to the scene. This can occur by virtue of improper storage or destructive analytical techniques, or the addition of transfer and/or pattern evidence to a victim's body or clothing during transport and/or storage.

Coroners: The actions of the coroner in removing the body from the scene can move evidence, obliterate patterns, cause potentially misleading transfer, and add artifact-evidence to the scene. This includes the physical removal of the body from the location where it was discovered, the placement of the body into a "body bag," and the process of transporting the body from the scene. These actions will change pattern evidence on the clothing of the victim and may destroy potential valuable transfer evidence.

Case Examples
The following case examples have been taken from the authors’ case files:

Example #1 - Fire and Suppression Efforts
A young female arrived at her older boyfriend's home, where he lived with his elderly mother and two teenage children. A confrontation ensued. The boyfriend and his mother, who were the only ones home at the time, were both killed, dying of exsanguination from multiple gunshot wounds.

The boyfriend's body was found outside of the residence with an associated blood trail. After the girlfriend removed some items of value she set both the house and the body of the boyfriend on fire.

Some of the actions and circumstances involved in the crime were evident, given the body outside of the home, associated transfer evidence, and blood patterns. However, a sequential reconstruction of the shots fired within the house, as well as the relative positions of the shooter and the victims, was significantly impaired. This was due to the movement and destruction of walls, furniture, flooring, household items, the body of the mother, and blood evidence in the scene. A crime analysis of the case reads in part:

…precise reconstruction efforts are hampered in this case due to the numerous destructive and evidence-altering variables that were imposed upon the scene in the interval after the deaths occurred and before it was safe for forensic efforts to take priority. These destructive and evidence-altering variables and elements, documented in part by a video made of this scene during and after suppression efforts were engaged, include, but are not limited to:

• the destructive nature of the fire itself, which involved both stories and many rooms in the house;

• the destructive nature of the suppression efforts, which involved water being pumped into the home at approximately 1000 gallons per minute, the destruction and movement of items in the home for both suppression and salvage purposes, as well as unintentional damage that may have been caused by heavy fire hoses in various locations within the home;

• the number of personnel venturing in and out of the home during and after suppression efforts, which some estimate may have been more that 50 individuals.

Example #2 - Decomposition & Insect Activity
An adolescent female was missing for approximately two weeks before investigators found her body. It was located in a slightly concealed area of foliage behind an unoccupied residence. Her deceased body had been placed inside of a piece of recently discarded carpeting, beneath a heavy metal water tank, and then covered by several more layers of older discarded carpeting.

According to the autopsy report, and visible in the autopsy photos, the victim's underwear was found in her mouth. The cause of death was determined to be "asphyxia by gagging" possibly in combination with a violent blow to the victim's jaw as evidenced by a fracture to the mandible.

The question arose as to whether there was evidence of manual or ligature strangulation. Due to the overall advanced state of decomposition, and the fact that maggots had consumed the soft tissue associated with the neck, a determination on this issue was not possible. In the absence of evidence to examine, one cannot make a legitimate determination as to whether or not manual or ligature strangulation occurred. This did not exclude the possibility that it may have occurred; merely that it could not be established and therefore should not be assumed for the purposes of analysis.

Example #3 - Secondary Transfer and Scene Technicians
The body of an adolescent female was found on a couch in her home where she lived with her mother and younger brother. She was wearing only a shirt and bra at the time of discovery. She was determined to have died of "asphyxia secondary to manual strangulation." She had a history of sexual abuse, suggested by the absence of her hymen and numerous anal scars, as well as a history of promiscuity. The DNA of one of her mother's lovers was found on her perineum, in the form of sperm.

Given the location and circumstances of the crime, the precise conditions of this exchange could not be reliably established. One possibility is that the suspect was engaged in some form of sexual activity with the victim, and that sperm transferred to her perineum as a result. However, the suspect and the victim's mother had sexual relations in the mother's bed, where the victim had been playing previously with her brother. There were also reports that the suspect and the victim's mother may have had sexual relations on the couch, were the victim would have been sitting. Additionally, a review of the crime scene video shows several evidence technicians moving evidence around on the couch and other locations, and then touching the victim's body in multiple locations, examining her body as it is being photographed, with and without gloves.

Given these circumstances, and the victim's history, the following are potential evidence transfer relationships in this case:

• From the suspect to the victim during a forced sexual assault;
• From the suspect to the victim during a consensual (but unlawful) sexual encounter;
• From the couch to the victim's perineum;
• From the mother's bed to the victim's perineum;
• From the scene technician's fingers to the victim's perineum

Example # 4 - Emergency Medical Technicians
A youth was stabbed several times by rival gang members. He ran for a home but collapsed in the walkway. A photo of the scene taken prior to the arrival of the EMT team shows a blood trail and that the victim was lying face down. Subsequent photos show the 5 EMTs working on the body on his back. He had been rolled over onto the blood pool. It became impossible for bloodstain pattern interpretation to be used to reconstruct the events leading to the death of the youth.

Example # 5 – Coroner Activities
Photos taken of the deceased showed isolated bloodstain patterns on the clothing of the victim of a rape homicide. She had been sexually assaulted and her throat was cut. The patterns on her panties appeared to be bloody transfers from a hand. The coroner refused to remove the clothing at the scene. When the panties were submitted to the laboratory they were soaked in the victim’s blood from transporting her in the body bag. The patterns were destroyed as well as making it impossible to isolate the stains for identification purposes.

Example # 6 – Victim Activities
In this case the victim’s actions prior to a crime caused "false evidence" to be present. A woman had sex with her boyfriend in his vehicle. He dropped her off at her apartment. As she enters her bedroom she surprises a burglar. A struggle ensued causing tears in her clothing before the burglar strangled her and fled. The boyfriend is suspected of the "rape/homicide." His DNA is found in her vagina. This would be considered proof of his guilt in many courts.

Fortunately, the boyfriend had an alibi; he was stopped for DUI a couple of blocks from the house. He was in police custody during the time the screams were heard by the neighbors.

Example # 7 – Family Activities
The body of an elderly man was found "in his bed." Upon examination, strangulation marks were found on his neck. These marks were consistent with a hanging. When questioned the family admitted that he had hanged himself. They didn’t want the "shame on their family," so they had cut him down, changed his clothing and put him to bed. The evidence was destroyed for cultural reasons.

Conclusions
The failure to consider Evidence Dynamics as a part of any crime reconstruction process has the potential to provide for misinterpretations of physical evidence, and inaccurate or incomplete crime reconstructions. Any subsequent use of the reconstruction for investigations, trial or behavioral analysis would have a diminished foundation and relevance, compounding the harm in legal, investigative and academic venues. It is the responsibility of the forensic scientist to perform reconstructions of the circumstances and behaviors involved in a crimes with care, and to be aware of the possibility of Evidence Dynamics, in order that opinions regarding reconstruction of the crime reflect the most informed and accurate rendering of the evidence.

Notes

1. For discussions, see: [3], [4], [7], & [11]

2. For example, an offender wearing a wool sweater kills a female in her home. The offender leaves a number of wool fibers behind on the victim's body. The victim's neighbor hears the struggle and discovers the body. While attempting to revive the victim, several of the wool fibers transfer onto his clothing. When the clothing is examined in the laboratory, wool fibers foreign to the location are found on both the victim and his clothing, causing investigators to suspect him of the crime. Unless the circumstances of the crime are thoroughly investigated, and the possibility of secondary transfer explored, the neighbor may be wrongfully charged with the crime.

3. Artifact-evidence is any change in crime scene evidence or addition to crime scene evidence that can mislead one into inferring that the "evidence" is related to the commission of the crime.

References

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