http://www.theforensicteacher.com/Evidence.htmlThe Myths of Circumstantial Evidence
By Ted Yeshion, Ph.D.
“Circumstantial evidence is a very tricky thing,” answered Holmes thoughtfully. “It may seem to point very straight to one thing, but if you shift your own point of view a little, you may find it pointing in an equally uncompromising manner to something entirely different.”
Sir Arthur Conan Doyle
“The Boscombe Valley Mystery,” The Adventures of Sherlock Holmes (1891).
Evidence is any physical item or information observed or gathered by crime scene investigators that may prove to be relevant to an investigation. The major role evidence plays in criminal investigations is to associate a suspect with a victim or with the scene of a crime. In criminal cases, the critical facts that require proof are whether a crime actually occurred and if the accused was responsible for having committed that crime. Evidence also plays a crucial role in the elimination of suspects and in the exoneration of the wrongfully convicted. Physical evidence (also referred to as real or direct evidence) is that which is tangible and can be observed with any of the five senses. Examples of physical evidence are blood, hair, fiber, fingerprints, shoe/tire track impressions, etc.
Generally, evidence can be classified into two categories: direct and circumstantial, although testimonial and documentary evidence are also important types of evidence used in court proceedings. Direct evidence provides proof about some fact in question without requiring jurors to make any assumptions or to draw inferences. It is evidence that clearly speaks for itself and directly leads to a definite conclusion or direction via deductive reasoning. Classic examples of direct evidence are eyewitness testimony, photographs or video of the defendant in the act of committing a crime, and incriminating statements made by the defendant, victim, or witness.
Unlike direct evidence, which relies on personal knowledge or observation and yields a definite conclusion, circumstantial evidence is based largely on inference and uses inductive reasoning. That is, circumstantial evidence is evidence that indirectly proves a fact or supports a theory. Indirect or circumstantial evidence implies that the defendant was involved in the crime, and is typically sufficient to convict a defendant if the evidence and inferences drawn from the evidence can be used to establish that the defendant is guilty beyond a reasonable doubt. This is the standard of evidence used in criminal trials to overcome the presumption that a person is innocent until proven guilty. Thus, evidence need not prove that the defendant is absolutely guilty or guilty beyond any question, but rather that there are no other logical explanations resulting from the case facts that anyone other than the defendant could have committed the crime. Guilt can be proven using a process of logical deduction. The burden of establishing proof beyond a reasonable doubt is the responsibility of the prosecutor. Real, direct, or physical evidence must be presented in court through testimonial evidence to establish a foundation for admissibility.
A confusing point for many is that legally, all forensic evidence generated by the wide variety of forensic specialty areas including fingerprint identification and DNA analysis, fall under the category of circumstantial evidence and therefore serve as only partial proof of a criminal act. Still, scientific evidence is often sufficient to resolve a criminal matter. An exception to physical evidence that does not fall into the category of circumstantial evidence includes illicit drugs, which simply by their presence violates a law. Consequently, there is no need for a judge or jury to make assumptions or inferences to reach a conclusion that the defendant is guilty of a crime.
Circumstantial evidence has a reputation for generally being weaker and less valid evidence than direct evidence. It is interesting and necessary, however, to emphasize that it is simply incorrect to assume that direct evidence is always stronger or more convincing than circumstantial evidence. Aside from scientific evidence, other examples of circumstantial evidence that may imply guilt include the defendant’s motive or opportunity to commit the crime, whether the defendant had resisted arrest, or if any suspicious behaviors were demonstrated. Unlike the incorrect examples perpetuated by television shows, movies, and novels, a majority of convictions are based solely on circumstantial evidence if for no other reason than this type of evidence is more commonly encountered at crime scenes than direct evidence. It is also important to note that direct evidence such as eyewitness identification and confessions given by suspects are fraught with potential problems as demonstrated by the investigations into 300-plus exonerations of wrongfully convicted individuals by the Innocence Project. The leading cause of wrongful convictions, especially in sexual assault cases is eyewitness misidentification, a prime example of direct evidence. Eyewitness identification has proven to be unreliable in approximately 75% of the 300 DNA exonerations, yet remains very persuasive as direct evidence for judges and juries. False confessions given by defendants, and incriminating statements made by jailhouse snitches and others have been found to occur in approximately 25% of all the DNA exoneration cases to date. Once jurors hear this type of direct testimony, it is nearly impossible to un-ring that bell.
Forensic scientists and investigators also divide evidence into further categories to include those demonstrating class and individual characteristics. Evidence with class characteristics help narrow the ability to identify an object or person to fewer possibilities and can also be used to exclude an object or person with absolute certainty. Examples of such evidence are blood types, individual fibers, microscopic examination of hair, and single-layer paint fragments. Such evidence cannot be used to link the physical evidence to a common origin to a high degree of scientific certainty. Evidence with individual characteristics, however, demonstrate unique qualities that can be used to link the physical evidence to one person or object to a high degree of scientific certainty. Examples of this type of evidence are the comparison of a latent fingerprint to a known inked impression with matching ridge characteristics, DNA profiles (with the exception of identical twins), bullets and tool mark impressions with matching striation markings, handwriting, comparison of wear patterns observed in footwear and tire track impressions, and when the edges of a broken object can be reconstructed in the manner of a jigsaw puzzle.
Although varieties of evidence having class or individual characteristics are still categorized as circumstantial, the relevant value of the evidence and therefore the weight given to the evidence by jurors will vary when presented during a criminal trial. The exclusionary power of each of these types of evidence is equally important in seeking justice as it can demonstrate that the wrong person was detained, arrested, or convicted.
The proper recognition, documentation, reconstruction, submission of relevant evidence, and preservation of evidence is critically important in all crimes scene investigations. This is not only necessary for current cases under investigation and those going through the trial process, but also to preserve evidence for those who claim they were wrongfully convicted. In these latter cases, remaining DNA evidence can be used to support or refute claims of innocence. When such evidence is not available, the truth may never be known and justice will not have been served.
Dr. Ted Yeshion is a professor of forensic science and criminal justice at Edinboro University of Pennsylvania. Prior to teaching, he worked 25 years as a forensic biologist, DNA analyst, crime scene reconstructionist, crime laboratory director and Special Agent. Dr. Yeshion also serves as the Chairman of the Science Subcommittee for the Pennsylvania Joint State Government Commission on Wrongful Convictions
