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INTRODUCTION TO FORENSIC
SCIENCE AND CRIMINALISTICS
The rational basis upon which the work of today's investigator is predicated is called the scientific method. This method is empirical (from the Latin empiricus, "experienced"), meaning that knowledge is gained from direct observation. Underlying the empirical attitude is a belief that there is a real knowable world that operates according to fixed rules and that effects do not occur without causes. In contrast to, say, religious dogma, science is open-ended: It is amenable to being amplified or to having its errors corrected in the light of new evidence. For our purposes, the scientific method is one that involves analysis (studying the unknown item to determine its essential characteristics), comparison (examining how the characteristics compare with the established properties of known items), and evaluation (assessing the similarities and dissimilarities for identification purposes).
Forensic means characteristic of, or suitable for, a court of law. Hence forensic science is a broad term that embraces all of the scientific disciplines that are utilized in investigations with the goal of bringing criminals to justice. The American Academy of Forensic Sciences defines it as "the study and practice of the application of science to the purposes of the law." It includes such fields as forensic medicine, toxicology, psychology, and anthropology as well as the work of specialized examiners of fingerprints, firearms, tool marks, and questioned documents. The term is so broad as to include even criminology, a social science that plays a role in the administration of civil law.
Like criminology, criminalistics is a division of forensic science, and its practitioner is called a "criminalist." The discipline has been variously defined. In 1963, the California Association of Criminalistics adopted the following definition: "Criminalistics is that profession and scientific discipline directed to the recognition, identification, individualization and evaluation of physical evidence by application of the natural sciences to law-science matters." This definition has since been adopted by the American Academy of Forensic Sciences.
At one time a criminalist might have been a generalist, but now most are specialists in one of many areas of expertise. These specialties include forensic chemistry, toxicology, drug analysis, serology, trace analysis, latent fingerprints, firearms examination, impression evidence, questioned document examination, and voice examination. Depending on the crime laboratory, some specialties may be combined with or separated from others. For example, because of the way they are compared, tool marks may be handled by the firearms examiner. Conversely, because of the increasing complexity of DNA analysis, it may be treated as a discipline separate from forensic serology, and crime scene examination may itself now be a specialized area of expertise.
In certain of the criminalistics disciplines, such as firearms examination and fingerprint identification, there is occasionally confusion between the terms identify and individualize. Although their respective Latin roots are similar (idem means "the same" and individus means "not divisible"), the terms are quite distinctive as they are correctly applied in criminalistics. As the great forensic authority Paul L. Kirk explains: "The terms `identification' and `identity' are used constantly by practitioners in the field. Few stop to define the terms. `Identity' is defined by all philosophical authorities as uniqueness.... Bowing to general scientific usage, we must however accept the term `identification' in a broader context referring only to placing the object in a restricted class.... In this sense, the criminalist would identify the object as a paint chip, but not relate it to the painted surface from which the chip was derived. He would identify a marking as a fingerprint, but without relation to the hand that placed it." Kirk raises an interesting point, noting that "for the criminalist to use the word `identification' in its accepted context is to admit that there is no reason for his special existence.... The criminalist does not attempt identification except as a prelude to his real function--that of individualizing. The real aim of all forensic science is to establish individuality, or to approach it as closely as the present state of the science allows. Criminalistics is the science of individualization."
Individualization--that is, demonstrating the uniqueness of some item of evidence--is made possible by the fact that no two things in nature are exactly the same. Nearly everyone knows that this is true of snowflakes and fingerprints. But it is also true of gun barrels, lip impressions, shoe prints, and pieces of broken glass. The principle that all objects in the universe are unique may be expressed in many ways:
No two things that happen by chance ever happen in exactly the same way.
No two things are ever constructed or manufactured in exactly the same way.
No two things ever wear in exactly the same way.
No two things ever break in exactly the same way.
Of course, items made from a mold will be very similar to each other, and as a practical matter it may not be possible to individualize, say, the track of a brand new tire. If the impression was clear, however, it should be possible to identify its class characteristics, discovering which brand and model of tire the tread pattern came from. Over time, the tire acquires nicks, patterns of wear, and sufficient individual characteristics, making individualization possible. In the case of a new tread, one could only say that the track could have come from a certain automobile--that the track was consistent with it. In the case of a nicked and worn tire, the criminalist would be able to compare the questioned evidence (the tread imprint) with that of a known standard (the suspect's tire or a test imprint made from it) to see whether or not the questioned impression may be individualized.
How many similarities are required to individualize an impression? In his book Individualization: Principles and Procedures in Criminalistics, Harold Tuthill writes, "The individualization of an impression is established by finding agreement of corresponding individual characteristics by such number and significance as to preclude the possibility (or probability) of their having occurred by mere coincidence, and establishing that there are no differences that cannot be accounted for." Tuthill notes that the words "an impression" may be replaced by "a bullet," "handwriting," "a break or fracture," or other wording appropriate to the evidence under consideration. So, there is no hard and fast rule; the number of similarities required for individualization will depend on the unique quality of the details discovered. "Whether or not we have found sufficient [numbers] will be decided, subjectively, in each case," Tuthill observes. "One will suffice, if it can be seen to be unique. It is for this reason that it is important for the criminalist to be well trained and have considerable experience before undertaking to give evidence as an expert witness."
In the process of individualization, the scientific examiner sometimes makes use of probability and may cite Newcomb's Rule (after Professor Simon Newcomb): "The probability of concurrence of all events is equal to the continued product of the probabilities of all the separate events." Consider a document typed on an old fashioned typewriter with the standard forty-two type bars and eighty-four characters. Suppose that examination of the document reveals that the machine that typed it has five individual characteristics--one caused by a misaligned type bar (a 1/42 probability) and the others caused by defects in individual characteristics (or 1/84 probability each). The mathematical formula for this set of circumstances would be: 1/42 x 1/84 x 1/84 x 1/84 x 1/84 = 1/2,091,059,712--a figure greater than the total number of typewriters of that particular model in existence. In many cases of individualization, the probability of each factor or "event" is unknown, and courts tend to take a dim view of assigning arbitrary values. Nevertheless, individualization, after the common-sense approach of multiplying each unusual factor by each additional one has been explained, represents the basis of many forensic comparisons presented in court.
The evidence that is encountered by the forensic scientist may be classified in various ways. Perhaps the simplest is the division into personal evidence, in the form of personal testimony, such as that of an eyewitness, and physical evidence, such as fingerprints or glass fragments. Personal evidence is subjective and colored by the person's attitudes and perceptions. In contrast, physical evidence is objective and remains the same for each observer, although there may be subjective aspects. Another system of classifying evidence is by the type of crime. Yet another is by the general nature of evidence: biological, physical, and miscellaneous (including polygraph tests, voice analysis, and photography). Still other methods are employed, including classification by the most-appropriate-laboratory approach. "In this scheme," states one forensic text, "evidence is placed into categories according to whether it is simply to be identified, an individualization is sought, or a reconstruction of the event is desired. Looked at in this way, evidence is examined and analyzed in a manner that is relevant to the investigation." In this regard we should mention corpus delicti evidence, the Latin phrase meaning "the body [or the essential elements] of the crime." This would generally be, for example, the body of a victim in a homicide or a broken or open strongbox in a burglary.
After results of a forensic analysis have been obtained, they must often be communicated to nonspecialists, including jurors. Whereas, generally speaking, a witness can testify only to facts that he or she knows, an expert witness is employed "because the issues require analysis and explanation by a person with scientific or specialized knowledge or experience." Hence an expert may give an opinion to the court when it is relevant both to the facts of the case and to the analysis conducted. The professional criminalist should withstand any pressure to support the case of the attorney who enlists him. Scientific integrity demands that he be as willing to clear the innocent as to incriminate the guilty.
The landmark case for the admissibility of scientific procedures and their results is Frye v. United States (1923). In Frye, the court stated: "Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs." Decisions subsequent to Frye made clear that general recognition--familiarity with a test or procedure by every scientist in the field--is not required for admissibility. Also "the particular field in which it belongs" was narrowed to mean the applicable specialty or subspecialty within a scientific field. And, in some instances, results or experiments devised in light of a particular problem were admitted if they were based on accepted principles of analysis and if a proper foundation has been laid.
In 1993, however, the U.S. Supreme Court, in Daubert v. Merrell Dow Pharmaceuticals, Inc., rejected the Frye "general acceptance" rule. An article in Journal of Forensic Sciences noted that many state high courts "have a very good grasp of scientific evidence and have enunciated readily-applied rules by which their trial courts are to evaluate it" and lamented the fact that "junk science" might find its way into the courtroom. The Supreme Court rejected these concerns, stating, "Vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence." The Court offered certain guidelines for gauging the validity of scientific evidence, emphasizing flexibility: the technique or theory must be testable and must have in fact been tested; it must have been subjected to peer review and the publication process; standards must exist and be maintained that control the operation of the technique; and the method or theory must have been widely accepted within the relevant scientific discipline.
While it is true that, as one forensic expert notes, "the idea of using science as an aid in criminal investigation was foreshadowed in the fictional works of Sir Arthur Conan Doyle at the turn of the century," there were in fact scientific advancements in crime detection long before Sherlock Holmes made his debut in 1887.
The earliest forensic scientists were medical men, who logically happened to be among the first on the scene of a death. The earliest record of physicians applying medical knowledge to the solving of crimes is the Chinese book Hsi Duan Yu ("The Washing Away of Wrongs") dating from 1248. Though it contains many unscientific notions, it also offers some important medical-legal procedures, such as distinguishing a case of drowning by the presence of water in the victim's lungs and identifying a death from strangulation by observing the characteristic pressure marks on the throat and damaged cartilage in the neck.
There were few advancements until the eighteenth century, when French medical jurist Antoine Louis sought not only to identify the cause of death but also to distinguish between murder and suicide in questionable cases and to solve other relevant matters. Eventually, such pathologists saw the utility of attempting to establish the victim's identity, determine the time of death, identify poisons, analyze bloodstains, and seek other advancements in the field of medical jurisprudence.
The end of the eighteenth century saw the origins of modern chemistry, which paved the way for the science of toxicology. Not surprisingly, the man considered "the father of forensic toxicology" was a medical teacher named Mathieu Orfila (1787-1853). Shortly after his graduation from the university in 1811, the Spanish-born Orfila became a private lecturer on chemistry in Paris. In 1813, he published the work on which his fame rests, Traite des poisons or Toxicologie generale. This was the first scientific study of the detection and pathological effects of poisons, and it established toxicology as a distinct forensic field.
Orfila had a rival, Francois Vincent Raspail, who was retained by the defense in the Lafarge case in 1840. Madame Lafarge was accused of poisoning her husband and indeed had purchased arsenic from an apothecary only days before his death. Chemical tests following the autopsy were inconclusive, however, and Orfila was summoned from Paris. The body was exhumed, and Orfila demonstrated the presence of arsenic in Lafarge's internal organs. In his trial testimony he assured the jury that both his laboratory ware and the cemetery earth were free of arsenic. Raspail, on the other hand, boasted he could extract arsenic from virtually anything--including the judge's chair--using Orfila's procedure. Raspail's testimony was delayed, however, when he fell while riding, and Madame Lafarge was sentenced to the penitentiary. The case is still cited as the first in which an attempt was made to rebut a state's witness by means of an opposing defense expert.
About this time the development of photography also became a technological boon to law enforcement as an aid to the identification of known criminals. As early as 1843 police in Belgium began maintaining files of daguerreotypes for such purposes, and France and the United States followed suit by the 1850s. Still later, the ability to produce multiple prints from negatives greatly facilitated the use of "mug shots" ("mug," the slang term for "face," may have derived from the eighteenth-century custom of fashioning drinking mugs in the form of grotesque human faces).
Even with the assistance of good photographs--a great improvement over memory--mistaken identifications were sometimes made. An example of tragic misidentification is the case of Londoner Adolph Beck who, in 1896 and again in 1904, was mistaken for the swindler William Thomas. Only a postponement and the interim arrest and correct identification of Thomas kept the unfortunate Beck from serving the second prison term. Photographs of the two men do show similarly stout men with walrus mustaches but with otherwise dissimilar facial features. But even photographs did not prevent mistaken identifications. As C.A. Mitchell warned in The Expert Witness, published in 1923, "Since a photograph represents only one aspect, and often a false one, of a person at a particular moment, there is a chance of its being mistaken for a portrait of someone else, who in reality is not at all similar, and the possibility of wrong identification may thus be intensified. There have, as a matter of fact, been numerous cases of mistaken identification from photographs."
The first really scientific attempt at identification of criminals was made in 1860 by a Belgian prison warden named Stevens, who began taking measurements of criminals' heads, ears, feet, and the lengths of their bodies. Stevens soon abandoned his imperfect method, but in 1879 Frenchman Alphonse Bertillon (1853-1914) began to develop an elaborate system of anthropometry (the science of measuring the human body). By 1882, his bertillonage was being used routinely to identify criminals through tabulation of such factors as height, sitting height, length of outstretched arms, length and breadth of head, length of right ear, and other measurements, as well as photographs. Although this cumbersome and fallible system was replaced after some two decades by fingerprinting, Bertillon's pioneering efforts earned him the sobriquet "the father of criminal identification."
Several individuals contributed to the science of fingerprinting, but credit is given to Francis Galton (1822-1911) for making the first definitive study of the subject. His most important contribution was that he developed a method of classifying fingerprints for filing. His Finger Prints, published in 1892, provided the first statistical evidence for the uniqueness of fingerprinting, and it described the fundamental principles that continue to apply to that method of personal identification.
It has been said that "the prototype of today's criminalist was fictional"--Sir Arthur Conan Doyle's Sherlock Holmes. In 1887, when the first Holmes story, A Study in Scarlet, appeared, scientific crime detection was still in its infancy, yet Doyle portrayed Holmes not as a mere armchair theorist as was Edgar Alan Poe's Auguste Dupin. Doyle wrote this early account of Holmes's approach:
He whipped a tape measure and a large round magnifying glass from his pocket. With these two implements he trodded noiselessly about the room, sometimes stopping, occasionally kneeling, and once lying flat upon his face. So engrossed was he with his occupation that he appeared to have forgotten our presence, for he chattered away to himself under his breath the whole time, keeping up a running fire of exclamations, and little cries suggestive of encouragement and of hope. As I watched him I was irresistibly reminded of a pure-blooded, well-trained foxhound as it dashes backwards and forwards through the covert, whining in its eagerness, until it comes across the lost scent. For twenty minutes or more he continued his researches, measuring with the most exact care the distance between marks which were entirely invisible to me, and occasionally applying his tape to the walls in an equally incomprehensible manner. In one place he gathered up very carefully a little pile of grey dust from the floor, and packed it away in an envelope....
"They say that genius is an infinite capacity for taking pains," he remarked with a smile. "It's a very bad definition, but it does apply to detective work."
The first real-life "scientific detective" was an Austrian lawyer named Hans Gross (1847-1915). When A Study in Scarlet appeared, Gross was making notes for a handbook to be used by his fellow magistrates. The finished work, titled Handbuch fur Untersuchungsrichter ("manual for examining magistrates"), appeared in Germany in 1893 and was eventually published in English as Criminal Investigation. Insofar as is known, Gross never read the Sherlock Holmes stories, yet his own work seemed to bring the fictional ideas to life. "You had only to open Gross' book to see the dawning of a new age," stated one admiring writer. In addition to advocating forensic medicine, toxicology, serology, ballistics, and anthropometry, Gross had chapters on employment of the mineralogist, ecologist, and botanist. "Dirt on shoes," wrote Gross in a typical sentence, "can often tell us more about where the wearer of those shoes had last been than toilsome inquiries." Gross also coined the term criminalistics and later launched the forensic journal Kriminologie.
A disciple of Gross (and, admittedly, of Sherlock Holmes) was a Frenchman, Edmond Locard (1877-1966) "I must confess that if in the police laboratory of Lyons we are interested in any unusual way in this problem of dust it is because of having absorbed the ideas formed in Gross and Conan Doyle," he said. This "problem of dust," or trace evidence, was of great interest to Locard, who was educated both in medicine and the law. He set forth the concept known as Locard's Exchange Principle, which states that a cross-transfer of evidence takes place whenever a criminal comes in contact with a victim, an object, or a crime scene. For example, a criminal may leave behind a latent fingerprint and a strand of hair while carrying away from the scene distinctive carpet fibers or other identifiable debris. In the case of three suspected counterfeiters who had been circulating bogus coins, Locard had the suspects' clothing brought to his police laboratory. Careful examination revealed tiny metallic particles in all three sets of clothing, and chemical analyses revealed that the particles had the same metallic elements as the coins. The suspects were arrested and, when confronted with Locard's scientific evidence, confessed.
Given the importance of bloodstains at the scenes of violent crimes, mid-nineteenth century medical-legal experts sought some means of identifying them. Microscopic examination worked on fresh blood, but the distinctive red blood cells broke up and lost their identity as blood dried. Attempts to identify blood chemically were only moderately successful, but the work of two European medical academics, one in Vienna in 1901, the other in Turin in 1915, represented major breakthroughs. Dr. Karl Landsteiner (1868-1943) worked as assistant to a professor of pathology and anatomy at the University of Vienna. After the turn of the century, he conducted experiments in mixing the blood cells and serum of different persons, which led him to the discovery that blood cells can be divided into groups, which were later designated A, B, AB, and O.
Leon Lattes (1887-1954), a professor at the Institute of Forensic Medicine at the University of Turin, developed a forensically useful application of Landsteiner's discovery. On September 7, 1915, a man came to the Institute with two small apparent bloodstains that had mysteriously appeared on the tail of one of his shirts. His wife was berating him over them, and he could not account for them except by speculation. Lattes thought it ironic that a marital dispute rather than a crime had so challenged him, but he set to work to find a means of dissolving the blood and testing it for type. As it turned out, the blood was the man's own, the result of discharge from prostate trouble! Soon, Lattes applied his newfound technique to bloodstains on an accused murderer's coat, exonerating him.
In the field of firearms examination, the U.S. Army colonel Calvin Goddard (1891-1955) laid the groundwork for the individualization of weapons. In the 1920s Goddard refined the process of comparing markings on a bullet taken from a shooting victim with those on one test-fired for forensic examination. Goddard used the comparison microscope for this as well as for comparing the firing-pin marks on shell casings. According to Richard Saferstein, "Goddard's expertise established the comparison microscope as the indispensable tool of the modern firearms examiner."
The greatest handwriting expert of his day, Albert S. Osborn (1858-1936) of New York City, developed the fundamental principles of questioned document examination and so is credited with that field's acceptance by the courts. As one writer observed, Osborn's career "is a history of handwriting testimony in America." Strange as it may seem now, "during his first year as an expert witness he was exposed to the scorn of judges who would not let him set up a blackboard in the courtroom or permit him to introduce, or even mention, evidence revealed by the microscope. Due to the ignorance of early jurors, it was perhaps preferable that they be told things instead of being shown them, but Osborn changed all that." The same source adds that when Osborn was testifying in the 1930s, the courtroom resembled "a scientific laboratory in which a professor was making a demonstration." Osborn left for posterity his monumental Questioned Documents, first published in 1910 and still used as a standard textbook in the field.
Among the important figures in the history of forensic science were those noted for their academic achievement and for the education of others. Dr. Paul Leland Kirk (1902-1970) stands out prominently in this group. Kirk was a student of chemistry and biochemistry and obtained degrees from Ohio State University, the University of Pittsburgh, and the University of California. From 1929 to 1945, at Berkeley, he rose from instructor to professor of biochemistry, taking time off during World War II to conduct plutonium research for the Manhattan Project. By 1934 Kirk began to apply biochemistry to forensic questions, conducting studies by the thousands. He also began to offer courses in criminalistics as part of the curriculum in biochemistry. Eventually, he became the head of the criminalistics department at the University of California's School of Criminology, founded in 1948-50. Kirk's comprehensive work, Crime Investigation, Physical Evidence, and the Police Laboratory, quickly became a standard in the field.
Among the more recent superstars of criminalistics are Dr. E. Roland Menzel, professor of physics at Texas Tech University, in Lubbock, Texas, and director of that university's Center for Forensic Studies. Beginning in the 1970s Menzel has pioneered in the application of lasers to criminalistics, especially their use in locating and "visualizing" latent fingerprints and other types of trace evidence, including biological.
Another modern giant is Alec Jeffreys, who, with his colleagues at Leicester University in England in 1985, discovered that portions of certain genes' DNA structure are unique to each person. For that reason Jeffreys named the process used to isolate and read these markers "DNA fingerprinting," now known among criminalists as "DNA typing". Routinely, such biological evidence as blood, semen, tissue, and hair is now being used to exonerate innocent suspects--even those who have been wrongly convicted and sent to prison.
We should, in our historical overview, briefly trace the development of the crime laboratory. The forerunner of such police facilities was the photographic studio, such as the one that originated in Belgium in 1843. Bertillon, the anthropometrist, expanded this facility into an identification bureau that was still far from the suitable laboratory Dr. Edmond Locard dreamed of.
Locard, known for his principle of the cross-transfer of evidence, was disappointed when he visited Bertillon in Paris, and his chagrin continued as he traveled to Lausanne, Rome, Berlin, Brussels, and even to New York and Chicago. Despite a lack of interest, in 1910 Locard was able to use his personal connections and influence to persuade the police prefects in Lyons to provide him with two assistants and makeshift quarters. The latter consisted of two attic rooms above the law courts, the entranceway to which, located on a narrow side street, also led to the prison and the archives. "Every day Locard climbed the steep winding staircase leading to his laboratory four floors up," writes Jurgen Thorwald in his Crime and Science. "Twenty years later when he already enjoyed world fame, he still worked up there in somewhat larger quarters, but still under the most primitive conditions, the heating consisting of wretched coal stoves which constantly deposited new layers of soot on the cracked walls." Locard began with only two instruments, an ordinary medical microscope and a small spectroscope (an optical instrument with a prism used to identify substances by the spectrum they emit when burned). These, together with some chemicals and basic lab ware, constituted the world's first scientific crime laboratory, later known as the Lyons Police Laboratory. Within a year Locard had proven the worth of the venture by solving the case of the three coin counterfeiters.
Among the early cases that helped establish Locard's reputation was the murder of a young woman in 1912. Her boyfriend was suspected but seemed to have an airtight alibi; he claimed to have spent the night in question with friends at a distant country house. When Locard was called in he went to the morgue to examine the body and observed strangulation marks on the girl's throat. Next he went to the suspect's cell, where he carefully scraped into small envelopes the debris from beneath the man's fingernails. Back at his laboratory, Locard discovered that the debris consisted of epithelial (skin) cells covered with a pink dust. Under the microscope, the dust proved to be a mixture of rice starch, magnesium sterate, zinc oxide, bismuth, and an iron-oxide pigment known as Venetian red. Locard requested from the police the cosmetics from the victim's room and found that her face powder, specially prepared by a local druggist, had the same ingredients. In the days before mass production of cosmetics, this evidence was enough to induce a confession from the boyfriend, who explained how he advanced the hands of his friend's wall clock to make them think he had been there at the time when the crime was committed.
Following Locard's success, what is now "the oldest forensic laboratory in the United States" was established in 1923 by the Los Angeles Police Department under the direction of August Vollmer. Vollmer was a remarkable man who rose from mailman to chief of police of Berkeley, where it is said he kept a copy of Hans Gross's Criminal Investigation on his desk. Vollmer served only a one-year term as chief of the Los Angeles Police Department, but the crime laboratory is an important legacy of his brief tenure. Seven years later, in 1930, the Los Angeles County Sheriff's Department set up its own laboratory, and the following year at Sacramento the California State Crime Laboratory was established. San Francisco and San Diego set up labs in 1932 and 1935, respectively. Each of these was quite small.
Perhaps the first truly significant crime laboratory that could be called a national lab was the Scientific Crime Detection Laboratory, which began at Chicago in 1929 and was soon affiliated with Northwestern University School of Law. The lab originated as a result of the infamous St. Valentine's Day massacre of that same year. When, during the grand jury probe, jurors learned there was no laboratory for testing the numerous bullets and cartridge cases, several influential members raised the funds to establish a permanent forensic laboratory. It was headed by Colonel Calvin Goddard, the pioneer in firearms identification, and appears to have been the first crime laboratory with a firearms examiner on its staff. In 1938 it was transferred to the Chicago Police Department.
The Bureau of Investigation, created in 1908, was reorganized by new director J. Edgar Hoover in 1924, when a national fingerprint file was established by adding fingerprint cards from the federal penitentiary at Leavenworth, Kansas, to existing bureau files. The official United States Crime Laboratory was established by the bureau in Washington, D.C., in 1930, and on November 24, 1932, was equipped to provide forensic science facilities to authorized law enforcement agencies and other government agencies. (The name Federal Bureau of Investigation [FBI] would be adopted in 1935.) Other laboratories were set up in Detroit, Boston, New York, Rochester, New Orleans, and Kansas City. Now numerous cities, counties, and states have crime laboratories or, as in Florida, laboratory systems.
Two years after the FBI laboratory was founded, England's Lord Trenchard established the Forensic Science Laboratory at Hendon. To form a closer contact with the Criminal Investigation Department (CID) it was soon moved to Scotland Yard in London. (The name Scotland Yard derived from the fact that the Metropolitan Police Headquarters, established in 1829 by Sir Robert Peel, in 1842 located its detective force partly at and partly near Great Scotland Yard, a small square where, centuries before, the Scottish ambassadors had lodged. Eventually, the name became attached to the detective force, then to the entire headquarters.)
Most forensic laboratories in the United States are publicly--that is, governmentally--operated, usually by law enforcement agencies but occasionally by prosecutors or medical examiners offices, or by departments of public safety. There are also private laboratories, some of which operate as commercial enterprises and others that are affiliated with universities. Since police-operated laboratories are usually unavailable to the defense in court cases, the private laboratories provide an important service in balancing the availability of forensic expertise.
THE MODERN CRIME LABORATORY
The functions of the modern forensic science facility are varied, but, as Paul L. Kirk writes in Crime Investigation, "perhaps the most important function of the police laboratory is to train the police investigators as to what constitutes physical evidence and how it is to be found, collected, preserved, and delivered to the proper laboratory investigator." According to Kirk,
As soon as the police investigator discovers how helpful a cooperative criminalist may be to him in increasing his efficiency, any distrust or jealousy of the laboratory worker should cease, and a fruitful and mutually profitable liaison will be established. This will result in more effective police work, which will benefit the entire force and the political subdivision it serves. Public relations will improve, police practice will be increased, and an atmosphere will be created in which confidence and respect, as well as more immediate personal advantages, will accrue to the force. The laboratory investigator and the police officer must always keep in mind that they are not competitive but complementary in their functions. The laboratory cannot produce unless the officer makes it possible, and the officer can solve many more crimes if he utilizes the laboratory to the fullest extent....
The study of physical evidence has a twofold purpose. First, and most important, it is often the decisive factor in determining guilt or innocence. Thus, the testimony of the scientific expert may be sufficient to determine the final decision of a court. It can do this by supplying the demonstrable facts, thus resolving discrepancies in ordinary testimony, and amplifying the information of the court to a point at which a true and just decision of guilt or innocence may be rendered, unclouded by divergent statements of uncertain or perhaps prejudiced witnesses. Second, the study of physical evidence can be a material aid in locating the perpetrator of a crime.
Physical evidence is often very useful to the police investigator before he has a suspect in custody, or in fact, before he even has suspicions of a possible perpetrator. If, for instance, the laboratory can describe the clothes worn by the criminal, give an idea of his stature, age, hair color, or similar information, the officer's search is correspondingly narrowed.
How the crime laboratory is set up depends on several factors, including the social nature and the size of the community that it serves, the anticipated case load, and the available facilities and funding. Cunliffe and Piazza recommend the following general divisions for crime laboratories. (Of course, larger laboratories would have more extensive capabilities.)
Photography Section. This will include the necessary equipment for crime scene photography, in addition to a studio for identification photos and other in-house photographic work, and a darkroom for processing all of the laboratory's film and prints.
Evidence Storage Section. This will consist of a secure area for evidence storage, and there will be employed a suitable receiving procedure to maintain the accountability of every evidential item and to ensure the continuity of the chain of custody. Every person who handles evidence must be accounted for to prevent questions about the integrity and even the authenticity of evidence.
Identification Section. This will include equipment and facilities for recording fingerprints of persons, both inside and outside the lab; for locating and recording latent fingerprints at crime scenes and on items of evidence transported to the lab; and for classifying and filing standard fingerprint cards. This section may also be charged with making casts of shoe and tire impressions.
Chemistry Section. Here a variety of tests and examinations will be conducted including drug identification, toxicology analysis, examination of body fluids such as blood and semen, and the restoration of serial numbers. Larger laboratories may have separate sections for drugs, toxicology, and serology.
General Examination Section. Because some areas overlap, this will be closely associated with the chemistry section. Here microscopical examinations are performed on soil, glass, paint, metal, explosive residues, hairs and fibers, and other trace evidence. Other types of examinations of physical evidence such as matching pieces of broken glass may also be conducted here. Ideally, there will be a separate section for document examinations.
Firearms Section. In addition to providing the capability of identifying firearms, bullets, and shell cases, and of associating spent bullets and cases with the weapons from which they were fired, this section should have a separate shooting room for firing test bullets and comparing gunpowder and shot patterns in making distance determinations. As necessary, this section should coordinate work with the chemistry, photography, and identification sections.
Instrument Section. Depending on need and resources, this section may be extensive or somewhat limited. Instruments ideal for the well-equipped laboratory include a gas chromatograph; an x-ray diffraction unit; an emission spectrograph; a mass spectrometer; infrared, ultraviolet, and atomic absorption spectrophotometers; equipment for thin-layer chromatography and electrophoresis; and a sound spectrograph.
Crime Scene Search Section. Today, large city and state crime laboratories often have sufficient caseloads and revenues to be able to develop teams of criminalists or specially trained technical investigators who search crime scenes and collect evidence for processing at the laboratory. That is the mission of this laboratory section.
Although there is the tendency today for criminalists to specialize, Cunliffe and Piazza caution that "it is a mistake for a laboratory to become overspecialized. Since almost everything can become physical evidence at one time or another, scientific investigation can encompass many different facets of science, including elements of physics, chemistry, biology, geology, and metallurgy." For this reason, they conclude that "it is desirable for the criminalist to be something of a scientific generalist."
Whenever specialized services are needed but are lacking at the local laboratory, the FBI laboratory can assist if a rather long wait is acceptable. Effective July 1, 1994, however, the FBI ceased to provide scientific examination in cases of property crime such as burglary, auto theft, nonfatal traffic accidents, fraud, or theft under $100,000, except cases that involve or were intended to cause personal injury.
One of the greatest resources of the FBI is their extensive reference collections used to help solve crimes. For example, for crimes involving firearms, they have available a Firearms Reference Collection containing more than two thousand handguns and over eight hundred shoulder weapons, used for the identification of gun parts and the locating of serial numbers; a Standard Ammunition File with over ten thousand samples of foreign and domestic specimens of ammunition; and a Reference Fired Specimen File consisting of test bullets and cartridge cases fired from weapons submitted to the laboratory. For questioned document examination they have on hand a Typewriter Standards File containing original specimens of typewriting from numerous and domestic machines; a Watermark Standards File, which indexes watermarks and brand names used by paper manufacturers and helps trace the origins of paper; a Safety Paper Standards File that helps determine the manufacturers of "safety" paper used for checks; the Checkwriter Standards File, which contains original impressions of checkwriters so they can be identified as to make and model; and an Office Copier Standards File, which aids in determining the manufacturers of photocopiers and duplicators.
The FBI also maintains reference files of inks; a special Anonymous Letter File with the handwriting, handprinting, and typewriting of extortionists, confidence men, and kidnappers; the National Fraudulent-Check File, which consists of photographic copies of the works of "bad-check artists"; and a Bank Robbery Note File.
Other fields of forensic science are well represented in the FBI laboratory. Investigations may be aided by a vast Tire Tread File of patterns furnished by manufacturers; a Shoe Print File; a National Vehicle Identification Number (VIN) Standard File, which allows lab personnel to determine the authenticity of a VIN number on a stolen vehicle; the National Automobile Altered Numbers File, which includes specimens of fake VINs found during investigations, the National Motor Vehicles Certificate of Title File with authentic samples from each manufacturer and state issuer as well as photographic copies of fraudulent titles and stickers; and the Explosive Reference Files with technical data and known standards of various explosive items and bomb components. There is even a Cigarette Identification File, which is used to identify cigarette butts found at crime scenes, and a Pornographic Materials File. In addition, the FBI laboratory maintains the Automobile Paint File, which can be important in hit-and-run cases; an extensive Hairs and Fibers Collection; Safe Insulation Files; Blood Serum Files; and an Invisible Laundry Mark File.
The U.S. Treasury Department also maintains reference files, notably, since 1968, a complete "library" of every available commercial pen ink. Inks are cataloged according to dye patterns developed by the technique known as thin-layer chromatography. In one case, for example, it was possible to demonstrate that a document dated 1958 was actually backdated, since a dye in the ink had not been synthesized until a year later.
Two important regulation processes have now been implemented within the forensic sciences: certification and accreditation. Several boards, including the American Board of Criminalists, certify individual forensic scientists as to their level of knowledge, skills, and expertise in specified areas. A critical part of the certification process is proficiency testing of applicants. Similarly, strenuous efforts are being made by the American Society of Crime Laboratory Directors (ASCLAD) to improve the quality of crime laboratories, including local, state, and federal facilities, by accreditation. One of ASCLAD's successes is that all federal laboratories are now obligated to seek the board's accreditation.
In closing this introduction to the crime laboratory in particular, and of criminalistics in general, it is well to consider these words from an article in the British Journal for the Philosophy of Science: "The scientist is indistinguishable from the common man in his sense of evidence, except that the scientist is more careful. The increased care is not a revision of evidentiary standards, but only the more patient and systematic collection and use of what anyone would deem to be evidence."