Grayce P. Storey
History and Development of Forensic Science
Forensic science is the application of science to criminal and civil laws that are enforce by police agencies in a criminal justice system.
Forensic science began with those individuals who developed the principles and techniques necessary to identify or compare physical evidence, and with those who recognized the necessity of merging of those principles into a coherent discipline that practically applied to the criminal justice system.
Many believe that Sir Arthur Conan Doyle, through his fictional character, Sherlock Holmes, popularized scientific crime detection methods. It was Holmes who first applied the principles of serology the study of blood, fingerprinting, firearm identification, and document examination long before their value was first discovered and implemented by real life criminal investigators.
The following are some pioneers who made early contributions to formulating the disciplines that now constitute forensic science:
Alphonse Bertillion began to develop the science of anthropmetry, a systematic procedure of taking a series of body measurements as a measure of distinguishing one individual from another, in 1879. Fingerprinting replaced this procedure in the 1900’s. Bertillion also earned the distinction of being the father of criminal identification.
Frances Galton undertook the first definitive study of fingerprints and developed a methodology of classifying them in 1892. His work described the basic principles that formed the present system of identification by fingerprints.
Leone Lattes discovered that blood can be grouped into different categories. Since 1915, blood types have been recognized as A, B, AB, and O. Today, his procedure is utilized often by forensic scientists.
Calvin Goddard refined the techniques to determine whether or not a particular gun has fired a bullet by utilizing the comparison microscope.
Education and Scientific Progress in Forensic Science
Forensic science includes specialists in pathology, psychiatry, and jurisprudence. Criminalistics is a subdivision of forensic science which involves the collection and laboratory examination of physical evidence from a crime scene or a suspicious occurrence . Items submitted to the criminalist laboratory might include a blood sample, a weapon, or bloodstained clothing from the crime scene.
There are three major subdivisions of the process of physical evidence evaluation: collection, laboratory evaluation, and court presentation of results and their significance. The crime investigator in each of the subdivisions should be well aware of which types of evidence are useful for investigative purposes, and what evidence the local, regional, or federal laboratory is capable of processing. The chosen evidence should be collected and transmitted to the laboratory in a manner so that the results of the laboratory will not be jeopardized. The crime scene should be surveyed by a trained criminalist who is responsible for the proper collection and transmission of physical evidence, unlike in the case of O. J. Simpson. Unfortunately, this practice is almost always restricted to major crimes (suicide, homicide, bombings, hit and run, etc.) The criminalist must be well aware of what he is looking for and the accuracy, precision, and investigative significance of his measurements.
In some jurisdictions, the local criminalistics laboratory is staffed by police officers who acquired their training on the job, which is essential to the practice of forensic science. These officers may not be equipped to broaden their laboratory’s capabilities in the examination of sufficiently wide range of evidence. In court on cross examination their testimony may be called into question on technical grounds, nullifying their work in the laboratory.
Local and regional laboratories should be well managed and adequately staffed by competent, scientifically trained criminalists who are given the opportunity and encouragement to update their education continually.
Entry into forensic science at the technical level requires training in mathematics, physical science, physics, biology, and particularly, chemistry. Most universities are capable of providing the basic scientific and legal courses, and the only elements needed to be added are the special coverage of forensic science topics and a field internship. Forensic science courses must be taught by professional criminalists who are both competent and enthusiastic.
A key to improving the methodology of forensic science lie in the hands of the research institutions. There is a substantial gap between the development of new technology and its application in t he field. This gap is primarily due to inadequate manpower and training and heavy workloads in the nation’s criminalistics laboratories.
Forensic research must be aimed at early solutions to urgent current problems. Laboratory techniques must be rapid and reliable in order to be useful and legally admissible. They must also give reproducible data which are scientifically acceptable. The case number is increasing where testimony must be supported by statistical data which substantiate the conclusion of the witness.
Function of the Forensic Scientist
The forensic scientist must be skilled in applying the principles and techniques of the physical and natural sciences to the analysis of the many types of evidence that may be recovered during crime investigations. The scientist must also be made aware of the demands and constraints that are imposed by the judicial system. The techniques and procedures utilized in the laboratory must rest only on a solid scientific foundation and satisfy the criteria of admissibility that have been established by the courts.
Methods of Forensic Science
The analysis of fibers is one of the most important tasks of the criminalist. In the laboratory fibers play an important part in finding traces of contacts which help to clear a case. Contacts are of the highest importance because by using them it is possible to prove one or several of the following points.
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1. The presence of the suspect on the crime scene.
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2. The way of the perpetrator’s flight or the way taken by the perpetrator of the crime to introduce himself to the scene of the crime.
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3. Contact with the victim.
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4. The use of definite tools (i.e.. weapons or vehicles).
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5. The wearing of clothing or shoes abandoned or denied.
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6. Contact of victim in an automobile hit and run accident with the car suspect.
Many factors depend on the value of these indicators. An intensive search for fibers in all zones of possible contacts and the use of an adequate technique for collecting evidence can give positive results.
White cotton is an example of collecting fibers that have no special evidential value because they are present always and everywhere. It is more fortunate when the scientist finds rare kinds of fibers or dyes with a high evidentiaryvalue.
A great part of the final success in collecting fiber evidence depends on correct sampling. Evidentiary value is especially diminished by carelessness. Faults made during this state of the operation are normally irreparable.
The first problem on the crime scene is to know where invisible fiber evidence might be located. Studying the modus operandi of the criminal is beneficial in finding all the regions he might have touched with his clothes (doors, walls, etc.). It is possible by following the visible or presumed way(s) step by step to collect evidence completely invisible to the naked eye. This procedure is done by pressing scotch tape to the surface of such hot zones. After folding the contaminated part upon a clean strip for further analysis the scotch tape with the lifted microscopic traces is not to be opened, so as to prevent any loss of evidence and prevent contamination with foreign dust.
If examination under a stereoscopic lens shows interesting details, a few of them are cut or punched out, while the remaining scotch tape is left intact for eventual controls to be examined by other experts.
It is of the highest importance to collect dust samples from zones the criminal definitely did not touch in order to get material for comparison and to know the normal composition of dust on the scene of the crime. The neutral sample makes it possible to determine in most cases immediately whether the fibers found have anything to do with the crime or not. The collecting of fibers from the clothing of the criminal himself and from his victim must be done in such a way that all possible information is preserved.
One of the most important sources for fibers is the human body (fingernails, pubic hairs, etc.). So as to avoid any loss of evidence, collection of samples must be done as soon as possible, preferably before the arrest and before a victim is brought to the morgue and washed.
If the collected fibers, especially the microscopic fragments have to be brought into court as a decisive means of proof, they must be handled with the maximum of care. Operators on the crime scene and in the laboratory must be able to assume responsibility that no contamination was possible during their work. It would be a great risk to touch alternately the clothes of the victim and the clothes of the presumed author of the crime. It may be well to treat each in separate rooms so that the microscopic preparations of single fibers meet only under the comparison microscope in order to avoid mixing up microscopic traces.
The first step from evidence to proof where of fibers are concerned is the identification of the fiber types. An investigation to the whole wardrobe of the individuals is necessary to determine whether or not the questioned type of fiber is present.
To the eye of the expert, most kinds of natural fibers are so familiar that one look under the microscope is sufficient to recognize the special type involved.
In a preliminary examination for studying details of fiber structure, it is advisable to begin any analysis with a pre-selection at a low magnification before opening the scotch tape or even before using a mounting medium. It is of great importance to study first the degree of dustiness of the fibers and eventually the adhering impurities which are able to increase the evidential value. This is why samples should not be cleaned. Cleaning often destroys traces of soap, water, repellent agents, dry cleaning, residues, moth repellents, etc., which may detected by ultraviolet light.
Mountings are made in an embedding medium with an appropriate refractive index in order to give the maximum of contrast.
The study of the general aspect of fibers includes not only the form and outline, but the natural ending of the fiber. To preserve these endings and not to cut all the fibers is most important.
Cross-section studies are not so important in natural fibers as in man-made textile. There is however an exception, such as in some plant fibers (hemp and flax) and animal hairs.