From the earliest times, the primary tools in the investigation of forensic cases have been observation and interpretation of physical evidence. Investigating authorities individually obtained scientific information from academic departments of chemistry or pharmacology, which had knowledgeable scientists and technical instruments such as microscopes. In some instances, scientific laboratories within the police organizations evolved from identification functions. Law enforcement could no longer depend on the memory of shrewd police officers “camera eyes” who knew the felons and their gangs so well that they could tell with accuracy whose handiwork was involved in a particular case. Initially, identification bureaus used Bertillon’s identification method, which was based on anthropologic measurements supported by photographic documentation. Bertillon’s technique was later replaced by the far more accurate technique of fingerprinting. The processing of fingerprints then became coupled with new responsibilities for handling physical evidence such as biological stains, hair, soil, and other materials left at the scene of a crime. The seeds of modern forensic science were sown in the last quarter of the nineteenth century. Progress from that time has been slow but steady.
Forensic Science:
Forensic science (often shortened to forensics) is the application of a broad spectrum of sciences to answer questions of interest to the legal system. This may be in relation to a crime or to a civil action. The word “forensic” comes from the Latin adjective “forensis” meaning of or before the forum and the term ‘forum’ simply means ‘where the justice is given.’ Forensic Science is the science of Justice, and the term ‘Justice’ here means “to protect the innocent and to convict the offender/culprit.” Forensic Science is not just like other sciences. In fact, Forensic Science is the science, which uses all the scientific methods/sciences, for the purpose of Justice. The term ‘science’ means anything, which is a fact, and which leaves no doubt and of course not framing two opinions. During the time of the Romans, a criminal charge meant presenting the case before a group of public individuals in the forum. Both the person accused of the crime and the accuser would give speeches based on their side of the story. The individual with the best argument and delivery would determine the outcome of the case. Basically, the person with the sharpest forensic skills would win.
Special Areas of the Forensic Sciences
Pathology - It was developed to study the problems related to unnatural death and various types of trauma to the living, for instance, deaths occurring during medical treatment, all violent and suspicious deaths occurring to individuals under custody in public or private institutions. The question of whether a death was accidental, homicidal, suicidal, or of undetermined cause must be answered on the death certificate.
Toxicology - The toxicologist, as distinct from the forensic chemist, primarily handles biological materials and can detect poisons in blood, urine, spinal fluid, gastric contents, bile, and tissues.
Anthropology - Forensic anthropologists are experts in the identification of bones and skeletal remains. Their studies provide information about sex, race, age, and time of death and even help in cases like mixing up of the children in the hospital. A recent application of this expertise was reconstructing the face of a skeletonized head.
Odontology - The odontologist, or dentist, provides information through examination of teeth and dental prostheses. This form of expertise may be used in living cases, as the examination of teeth is helpful where there is a possibility of a hospital mix-up of children, as such examinations may depend upon the presence on inherited characteristics in teeth, and help in cases disaster or homicide. Bite marks may be studied by these scientists.
Engineering - The investigation of accidents involving vehicles in traffic, recreational vehicles, or aircraft or industrial, fire, electrical, or metal fatigue accidents has brought into the picture those who develop and apply engineering principles to the solution of the cause of accidents. Thus, forensic engineering has been added to the other areas of the forensic sciences.
Biology - The examination of plant life, insects, soil, trees, dirt, seeds, and pollen, as well as blood analysis, can be a means of developing new resources to a forensic investigation.
Geology - This field provides information on rocks and geological material which can offer a very important advance to forensic investigation where evidence of this nature is found on a car. Geological principles can be used to determine where the car has traveled or where a murder victim with dirt or rocks on her clothing may have been murdered or taken.
Psychiatry - The psychiatrist is vital in solving many forensic problems. Psychograms, which analyze behavior personality and psychiatric problems, can offer a profile of an assailant to law enforcement officers. This in-depth investigation may bring out predisposing behavior, suicidal traits, or financial or alcoholic problems important in establishing causes contributing to the manner of death.
Questioned Documents - The QD examiner’s work includes the examination of handwriting, ink; paper, typewriter or printer impressions, or any other form of writing or printing that may have been used in a case. This expertise includes detection of counterfeiting and various types of fraud involving government paper, checks, forms, money, and credit cards or the possible falsification of entries in a ship’s log. The investigation of computer fraud may also examine the validity of printout material.
Criminalistics - Criminalistics requires several types of expertise. A large criminalistics laboratory may have sections specializing in firearms and explosives examination, tool mark examination, document examination, biologic examination, physical analysis, chemical analysis, soil analysis, and identification.
Jurisprudence - The expertise of the professional scientist can be of little value unless it is properly presented in a court of law. Consequently, the American Academy of Forensic Sciences (AAFS) has developed an area concerned with jurisprudence, which offers the practicing attorney the opportunity to learn what may be obtained from the insight and testimony of an expert, so that there can be more definitive preparation and utilization of the expert witness.
Following are some other important area’s of Forensic Science:
§ Computational forensics concerns the development of algorithms and software to assist forensic examination.
§ Digital forensics is the application of proven scientific methods and techniques in order to recover data from electronic / digital media.
§ Forensic archaeology is the application of a combination of archaeological techniques and forensic science, typically in law enforcement.
§ Forensic DNA analysis takes advantage of the uniqueness of an individual's DNA to determining paternity/maternity or placing a suspect at a crime scene.
§ Forensic entomology deals with the examination of insects in, on, and around human remains to assist in determination of time or location of death. It is also possible to determine if the body was moved after death.
§ Forensic geology deals with trace evidence in the form of soils, minerals and petroleum’s.
§ Forensic interviewing is a method of communicating designed to elicit information and evidence.
§ Forensic meteorology is a site specific analysis of past weather conditions for a point of loss.
§ Veterinary Forensics is forensics applied to crimes involving animals.
Victim
Suspect
Crime Scene
Aim of Forensic Science is to establish link with each other
Forensic Science helps in Identification of Criminals with:
Fingerprints
Fingerprint ridges are formed during the third to fourth month of fetal development. All fingerprints have a unique combination and arrangement of patterns and ridge characteristics. No two prints have ever been found to be exactly alike. Fingerprints are not inherited. Finger prints can not be altered. Prints remain the same throughout life.
Body Prints
Just like fingerprints, handprints have their own unique ridges. The ridges of the fingertips continue down to the palm and can also be used for identification.
Shoeprints can be lifted or developed in order to compare worn edges or differences in the bottom of the shoe. The way a person walks causes the shoe to be worn in a certain pattern and there will be breaks or small rock indentations. Feet also have unique prints like fingers that can be used to identify with a suspect print.
Each of the thirty-two teeth in humans is unique due to age and wear. Bites can tell how quickly the offender subdued the victim. Bites can often be matched to dental records. Forensic dentists assist in crime solving by studying teeth and teeth impressions. Eighty percent of the time teeth impressions are used to identify unknown victims.
The retina is located inside and at the rear of the eye. A retinal scan works on the principle of retina pattern uniqueness. It records the reflected vasculature contrast information and maps the capillary pattern of the retina. This type of scanning is considered exceptionally accurate. Retina scanning works for user identification and verification.
The chemical structure of DNA in everyone is the same. The only difference is the order of the base pairs. Like in fingerprinting, there are so many millions of base pairs in everyone’s DNA that every person has a unique sequence. Every person could be identified using the sequence of their base pairs. Since 1987, more than 150 cases have been decided with the assistance of DNA fingerprint evidence. DNA patterns are inherited from parents, and can therefore be used to indicate paternity and maternity. DNA analysis can be used to determine whether or not a suspect was at a crime scene. DNA can be found in blood, hair, skin cells, semen or other genetic evidence left at a crime scene. It can also be used to determine the identity of a victim.
Trace evidence can be found at crime scenes. It can be anything from strands of hair or skin cells to tool marks and physical (fracture) matches. Trace evidence can be used to identify a victim or suspect or determine how a crime was committed.
o Hairs and fibers may be transferred from the suspect or the suspect’s clothes to the victims’ and vice versa.
o A pedestrian struck by a vehicle may leave hairs and fibers on the suspect’s vehicle bumper or windshield.
o Carpet fibers can attach to a suspect’s shoes.
o Hair can usually be found on the floor near the weapon or point of impact between suspect and victim.
o Paint can be transferred from one vehicle to another in an accident.
o A paint chip left at the crime scene can be used to determine the make and model of the vehicle it came from. Most paint evidence submitted to a lab will come from hit-and-run cases involving automobiles.
o Paint transferred from a window to a suspect’s tool in a break and entry can place that tool at the crime scene.
o Powders and exploded/unexploded devices can be examined to determine what type of explosive may have been used.
o After the Bomb Squad makes sure a device is safe, they submit a sample of the explosive or the debris to the Trace Unit.
o This will identify which type of explosive was used.
o In car accidents, fragments of glass can be embedded in a victims’ hair or clothing.
o In break and entries, suspects often get glass fragments on their clothing.
o Glass particles can be compared to particles collected from the crime scene to determine if they have a common origin.
o Can reveal where a person has been, where they live, where they work, and if they have pets.
o Alibi soil samples are taken in many criminal investigations.
o Most soil samples are from the top surface of the soil, and involve taking little more than a tablespoon.
o Includes ammunition, components and residue.
o Characteristics are examined to fins a match.
o Bullets are never removed from their holes. The whole surrounding surface is cut out.
o Gunshot residue from the hand or face needs to be done within six hours, and a lab can compare it with target residue.
o Semen, saliva or sweat can usually be found in spatters, drops or stains.
o Bodily fluids, such as vomit, can be found at scenes involving alcohol, drugs, and poisons.
o Cigarette butts may contain dried saliva
o Semen containing sperm is particularly valuable for DNA analysis
Blood
o There are 150 known proteins, 250 known enzymes, and many more antigens in blood.
o Investigators can often estimate the time a crime occurred from how dry the blood is.
o The shape of blood at the scene (pool, drops, stains, or splashes) can provides clues as to what happened.
o In motor vehicle accidents, the officer can examine the headlights from a car in order to determine if the headlights were on at the time of the collision.
o The filaments in the light bulbs are examined for oxidation, hot stretch, cold breaks, rain bowing, and fused glass particles.
o Impressions can be three-dimensional when left in snow or soft soil, or they can be two-dimensional when a dirty, bloody, or other impression is left on a hard surface.
o Footwear impressions can lead to identification of a suspect because of the treads on the shoes that are worn down to each persons walking style. There may also be accidental scratches, nicks and cuts are left on the bottom of your shoe.
o Comparison between two cut, broken, or torn objects to determine if they were part of the same object.
o When an object breaks, tape is torn, or something is cut, two unique edges are formed. These edges can be compared by the naked eye, and under high magnification to see if they fit together like puzzle pieces.
o If the edges fit together they are said to physically match one another. It can then be said that the two objects were at one time a single object.
o Extractions and identifications are made using the gas chromatograph or the gas chromatograph/mass spectrometer.
o Analysis is typically for the presence or absence of petroleum products although other non-petroleum based accelerants may be identified.
o When a tool is made and used, tiny nicks and chips begin to form.
o Tool marks can be found at break and enters, robberies and other crime scenes where tools where used.
Wounds
o Wounds can often be matched to weapons, tool marks on the weapon, or at least the weapon's size, shape, and length.
o Wound pattern analysis is a special technique that often provides clues.
o Everyone has a unique style of handwriting.
o Most computers and printers also have a unique printing style.
o Document examiners can establish similarities in handwriting, and computer forensics specialists can often determine the make printer used to type a document.
Miscellaneous Unknowns
o There are many different types of evidence or unknowns found at crime scenes which are submitted to the Trace Unit.
o The Trace Unit can determine what the items are or make a comparison.
o Trace Evidence Unit of the laboratory attempts to identify the unknown evidence through the use of numerous microscopic and chemical analyses.
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