Definition
There have been many changes regarding the definition and common usage of the word “forensic.” In college English departments, the term refers to a formalized debate. It is not uncommon for “forensic” mail, intended for the English department, to be delivered to the Forensic Science department in error. The addition of “science” to the word “forensic” implies a scientific debate. In the early 1900s, what we now refer to as forensic science was referred to as police science. Crime laboratories, as they were previously known, are now called forensic laboratories. Currently, the term is overused, and many jobs only remotely related to a legal activity or the courts have the adjective “forensic” attached to their job title. Television news coverage, reality and true crime programming, and prime-time crime dramas have had a great influence in perpetuating the overuse of the term.
Forensic science refers to the legal debate related to the scientific examination of evidence and its admissibility and value in a court of law. The debate is refereed by the judge, takes place in a courtroom, and involves the defense, the prosecution, and expert witnesses in a case. This debate is based on both legal issues and the valid application of the scientific method and technologies to the examination of the evidence.
History of Forensic Science
Historically, modern forensic science as we practice it today had its foundations in England and Europe in the 1800s, even though ancient history has many examples of forensic science being practiced. The practice that has evolved into the contemporary medical examiner system can be traced back to the British coroners, public officials who would pronounce a person dead and could describe the cause of death.
Physical evidence, prior to that time, was of much less importance than the testimony of an eyewitness. Behavioral studies since have shown that several people witnessing the same event will often have radically different accounts as to what occurred. For this reason alone, the importance of physical evidence became widely relied upon and required the associated development of a scientific basis for the analyses—hence the birth of the various forensic specialties.
In the 1800s, Hans Gross, a German, and Edmond Locard, a Frenchman, were responsible for developing the scientific principle for the exchange of trace evidence between two objects that come in contact with each other. This principle is the basis for seeking evidence that has been transferred to or from the people or things that come in contact with each other at a crime scene.
In 1923, Chief August Vollmer of the Los Angeles Police Department established a laboratory within the department where they practiced “police science” and used the scientific method in working their cases. Scientists were sought out by the police to help them solve problems. University professors served as some of the earliest forensic scientists. In the 1930s, Vollmer headed the first university program in the United States for criminology and criminalistics, at the University of California, Berkeley. It was not until 1948 that the university officially formed the School of Criminology, headed by criminalist Paul Kirk. Today in the United States there are more than forensic laboratories at the federal, state, and local levels and numerous private forensic laboratories. Many European forensic institutes were formed after World War II.
Forensic Science Specialties
There are many forensic science specialties, as exemplified by the various sections of the American Academy of Forensic Sciences (AAFS). AAFS was formed in 1950 and today has more than six thousand members internationally. The forensic specialty sections at AAFS are general, criminalistics, engineering sciences, jurisprudence, odontology, pathology/biology, physical anthropology, psychiatry/behavioral sciences, toxicology, and questioned documents.
Digital Evidence
The newest section under consideration by AAFS is a Digital and Multimedia Section. With the advent of personal computers, cellular telephones, and digital photographs and movies, information in a digital format has become a new category of forensic evidence. The Scientific Working Groups for Digital Evidence (SWGDE) and for Imaging Technologies (SWGIT) were developed and supported by the Federal Bureau of Investigation (FBI) so that forensic experts can work together to develop consensus guidelines for how digital evidence is to be identified, collected, preserved, and examined for evidence of a crime.
The development of the Internet has been a wonderful resource for forensic science while at the same time an international phenomenon for new forms of criminal activity. In past years, it was obvious when a bank was being robbed. Today, banks can be robbed electronically without it being immediately obvious to the customers or even the bankers themselves. E-mail and chat rooms can pose many dangers for children and adults alike. Luckily, forensic evidence exists on the Internet and on all electronic devices.
”Computer forensics” is a term that has been used to describe evidence on computers. It has almost become outdated, given the advent of cell phones with numerous computer-like capabilities and automobiles that operate almost completely by computer chips. ”Digital forensics” is a more inclusive term that covers all technologies operating in a binary format. Universities are developing programs to meet these new challenges and to develop the scientific basis for these new digital forensic specialties.
Public Opinion
After the O. J. Simpson trial, ”forensic” became a household word. This was later followed by numerous television shows, including the very popular CSI (Crime Scene Investigation) series. The public has been given both unreal expectations for forensic science laboratories and the false appearance that forensic scientists can be investigators in designer clothes at a crime scene as well as scientists in the laboratory. This has been referred to as the ”CSI effect” by the US News & World Report (Roane 2005). Juries, based on their television knowledge, now second-guess the real forensic scientists during trials. It is important to remember that real-life forensic scientists work within a real-life legal system; sometimes justice prevails and sometimes it does not.
Professionalism
Forensic science is practiced by extremely dedicated professionals. Their opinions, while their own, are based on valid science. They must try not to be unduly influenced by the press or higher authorities. To that end, laboratory directors, with the assistance of the Federal Bureau of Investigation (FBI), formed the American Society of Crime Laboratory Directors in 1972. This professional organization supports the development of laboratory managers with high standards in both ethics and forensic science.
The Scientific Method
The basic process that a forensic scientist follows when looking at a crime scene or examining evidence in the laboratory is first to clearly understand the circumstances of the crime and the examinations requested by the law enforcement investigator. These observations along with the information that the evidence reveals allows the scientist to formulate what happened, how it happened, and when it happened. The initial assumption and rationale are considered a hypothesis. Further examination of the evidence and comparing the questioned exhibit to a known sample verify or discredit the original hypothesis. The examinations continue and comparisons are made until there is a clear association of the evidence with the crime, a clear exclusion of such an association, or a clear indication that the evidence is unsuitable for reaching a conclusion.
The implementation of the scientific method will extract the truth in a manner that can be duplicated by others who follow the same procedures. The scientific method as it applies to forensic science is as follows:
1. The forensic scientist makes an observation at a crime scene or about a particular item of evidence.
2. Based on the observations, the scientist develops a theory about what took place; this is referred to as “developing a hypothesis.”
3. The scientist tests the hypothesis using logic and experimentation, including only those things in the experiment that are relevant and excluding those that cannot be proved relevant or whose source is unknown.
4. The scientist tests the hypothesis by examining the results of the experimentation, which lead to particular changes to the original hypothesis, the experimental design, and/or the way the experiment was conducted.
5. The testing and subsequent alterations of the hypothesis are repeated until all of the experimental data from the testing results in proving one solid and well-defined hypothesis.
The Role of the Forensic Scientist
The role of a forensic scientist is to use the logic of the scientific method when conducting the various observations and examinations of physical evidence. It is not the forensic scientist’s role to determine guilt or innocence of the suspect, but rather through observation, experimentation, and interpretation of physical evidence, they determine what happened, how the crime took place, when and where it happened, and who could have been at the crime scene during the crime.
Because the U.S. legal system is based on the “presumption of innocence until proved guilty,” it makes sense that the forensic scientist might assume that the evidence will support the innocence of the suspect. By developing a hypothesis of innocence, the forensic scientist tests the hypothesis by trying to prove that the physical evidence was not involved in the alleged crime and that the crime was not committed by the suspect. When all hypothetical theories, experiments, and data cannot uphold the suspect’s innocence, but rather put the suspect at the crime scene holding the gun that killed the victim, then the “presumption of innocence” may not be upheld.
Evidence Examination
Typically, the “presumption of innocence” is the mind-set for all forensic scientists. The actual approach to evidence examination involves comparing a questioned exhibit from a crime scene to a known exhibit taken from a suspect by the investigator. Forensic laboratories and their scientists are given the legal responsibility to take possession of the physical evidence, to protect it from damage, contamination, or alteration, and to keep it under their care and control while they perform their scientific examinations. They make scientific observations that fall into three categories:
1. The evidence can be connected to the crime scene or victim.
2. The evidence can be eliminated as being related to the crime scene or victim.
3. The evidence is inconclusive.
In a criminal investigation, forensic scientists examine and analyze evidence using such tools as basic optical microscopes, which enhance visual observations. Evidence examination also utilizes advanced instrumentation such as infrared spectrometers, gas chromatographs, mass spectrometers, and scanning electron microscopes with energy dispersive X-ray analysis. Such instruments can be used to separate complex chemical and biological mixtures and to identify the molecular structure of each compound or elements of interest in the evidence related to the investigation of a crime. The scanning electron microscope is capable of doing elemental analysis of each layer of paint in a small paint chip that adheres to a pry bar for comparison to a known sample of paint from the door facing supposedly attacked by the pry bar. Computer databases allow for matching genetic material, deoxyribonucleic acid (DNA), from the biological stain at a crime scene to an individual whose DNA is in the national database.
Using science and technology allows the forensic scientist to draw conclusions about the evidence that is legally sound and scientifically valid. Information and physical evidence used in forming a valid conclusion must be attributed to a specific source. That source may be a class or group of items or connected to one specific item or person. If there is any question that the information or evidence is suspect or contaminated, it should not be analyzed or used as a basis for conclusions.
The science used to examine evidence must not only be valid but also provide a traceable chain of custody for each item of evidence, which must be maintained from the crime scene to the courtroom. In order for items of evidence that were examined by the forensic scientist to be admitted into court, the items must be handed to the expert on the witness stand for identification. The expert then describes from whom the evidence was received, how it was received, and how it was returned to the investigator. The expert will have made a mark in the evidence (usually initials and the date of examination or receipt), or if the evidence is very small and in a container, the expert will have initialed and dated the container, the seal, and the evidence tag. Without this secure chain of custody, the best scientific evidence will not be admitted into court as evidence.
The Forensic Scientist in Court
Forensic scientists must be qualified as an “expert” each time they go to court to testify in a particular case. Once qualified as experts, they are able to give their opinions on matters related to the evidence they have examined and analyzed. Nonexperts must testify to only the facts. After the expert is sworn in and on the witness stand, the individual must be “qualified” as an expert by a process called voir dire. The prosecuting attorney will ask his or her name, place of work, job title, length of time employed as a forensic scientist, education and training, number of publications, other experience relevant to expertise in the matter before the court, number of cases worked, reports written, testimonies given as an expert, so forth.
The defense attorney will then either accept the forensic scientist as an expert or ask additional questions that might discredit him or her, such as ”Have you ever failed a course in college?” “Is the college you graduated from accredited?” “Have you ever made a mistake?” ”Have you ever driven your car after drinking alcohol?” ”Have you ever been arrested?” ”Have charges of any kind been filed against you?” ”Can you list three journals in forensic science that you have read in the past year?” If things are brought out that the jury might find questionable about the expert, then the prosecutor will redirect questions that will allow the expert to clarify any misleading impressions that the defense attorney’s questions might have created. The defense can also have a redirect.
Once qualified, the expert is handed an item of evidence by the prosecutor and asked to identify it. Once the expert identifies the evidence item, questions begin as to the chain of custody and security of the evidence while in the expert’s possession and, finally, the results of the examination. After this direct examination by the defense attorney, which may be minutes, hours, days, or weeks (depending on the circumstances), the defense attorney has the opportunity to cross-examine the expert. If the evidence is strong, the defense will attack the credibility of the expert.
Expert witnesses are called to render opinions as to the value of evidence they have examined or reviewed. The prosecution will have an expert testify to his or her findings. The defense will likewise have an opposing expert to refute the findings of the prosecutor’s expert. For scientific evidence to be entered into court under the Frye standard, which dates back to 1923, the scientific specialty or technology has to be “generally accepted” by experts in the field.
In 1993, Daubert v. Merrill Pharmaceutical resulted in the judge being the “gatekeeper” for admitting scientific evidence into court. Both Daubert and later Kumho inquiries regarding scientific processes indicate that they should be flexible and suggest that the scientific theory or technique should be tested and its error rates known, should have relevant scientific articles published in peer-reviewed journals, should have standards related to the techniques applied, and should be accepted by the relevant scientific community.
The jury or judge (if the trial is before only a judge) has the responsibility to interpret all of the evidence, including physical evidence presented by the forensic scientists, and the testimony of witnesses, investigators, and the suspect to determine guilt or innocence. If the evidence is not strong enough to make a decision of neither guilt nor innocence, it is referred to as a “hung jury.” The case will either be dismissed or scheduled for a retrial.
Forensic science specialties will continue to evolve as we move into new lifestyles and new technologies are developed. New issues and new evidence will always be facing our society and the forensic science community. The basic principles and ethics of forensic science, however, will remain the same.
