Forensic Science

Forensic Science is any aspect of science as it relates to the law. Typically, it includes the disciplines listed below, but just about any area of science could be called into question in a court of law.

Forensic Medicine or Medical Jurisprudence

A specialized area of medical practice, concerned with the relationship between medicine and the law. More specifically, forensic medicine is the scientific use of medical and paramedical specialties, as well as various dental, psychological, biological, chemical, and mechanical techniques, in investigating the causes of a person's death, disability, injury, or disease. It is used in the pursuit of justice in court proceedings and in the protection of the public from environmental hazards.

Crime Scene Investigations

Historically, it has been customary to designate the crime scene as the area where a criminal act has taken place. Actually, the crime scene may comprise more than one site. In the macroscopic sense, crime scenes could also refer to areas other than physical locations. For example, the victim's body, the suspect's body, or any part of a vehicle used in connection with the crime are considered crime scenes. In addition, other locations or persons involved in the crime are regarded as continuations of the crime scene(s). In the microscopic sense, any piece of physical material related to the crime is also deemed a crime scene, such as a cigarette butt or the scrapings of a victim's fingernails. Each case, therefore, may contain many of these microscopic and macroscopic crime scenes and each could yield information useful to the solution of the crime.

Crime Scene Reconstruction

Crime scene reconstruction is the process of determining the sequence of events, criminal activities, and logical predictions about what occurred during and after the crime. Crime scenes are generally reconstructed through study of the crime scene patterns, application of logic, and the examination of physical evidence. Reconstruction not only involves the scientific analysis of a scene, interpretation of scene pattern evidence and laboratory examination of physical evidence, but also involves a systematic study of related information and the formulation of a logical theory. Often, it is extremely important to determine the actual sequence of events of a crime, to verify statements, to limit the possibilities of alibis, and to develop investigative leads. The need to conduct a scene reconstruction is one major reason for maintaining the integrity of a crime scene. If the scene was altered during processing, this will sometimes seriously affect the ability to perform reconstruction.

Forensic Anthropology

Well, from within the specialized area of osteology--the study of bones--comes the application of the methods and techniques of analyzing skeletal remains to cases of legal importance. Osteological analysis yield clues as to how populations of people might have lived, how old they were when they died, if they were female or male, their state of health (or disease), types of trauma they may have experienced as related to climate, warfare, or occupation. When we apply methods of studying the skeleton to cases of unknown modern remains, we are using osteology in a legal context; therefore we are practicing forensic anthropology (forensic means legal). Forensic anthropologists help identify individuals who died in mass disasters, wars, or due to homicide, suicide, or accidental death.

Forensic Artist (Facial Reconstruction)

Using a combination of tissue thickness’ and muscles, very good results have been obtained. This technique builds upon:

Skills - Reconstruction
Data - Measurements

All these contribute to the accuracy of the reproduction. The identification of human remains is of paramount importance for legal and humane reasons. The reconstruction of the facial features of an individual onto the skull is a blending of the scientific and the artistic skills of the sculptor. This method is often used as a last resort to identify the skeletal remains of an unidentified person. There are numerous techniques to sculpture a face onto the skull, all of which rely on the reproduction of a potentially recognizable face using the published soft tissue thicknesses in different racial groups.

Forensic Entomology

The application of the study of insects and other arthropods to legal issues. Entomology is the study of the life cycles of insects. It can be divided in three subfields: urban, stored-product and medicolegal. Medicolegal Entomology is the science of using insect evidence to uncover circumstances of interest to the law, often related to a crime. The time of death, for example, can usually be determined using insect evidence gathered from and around a corpse, provided the evidence is properly collected, preserved and analyzed by an appropriately educated forensic entomologist.

Forensic Odontology

The art and science of dentistry and paradental knowledge to the solution of legal issues in civil and in criminal matters. Dental implants, braces, and other types of dental work are often recovered with a body. These devices are extremely useful in identification because they are so unique to the individual and are well detailed in antemortem radiographs and medical records.

Forensic Pathology

The study of violent, sudden, and unexpected death. Pathology is the branch of medicine associated with the study of structural changes caused by disease or injury. Forensic pathology simply adds the word "unnatural" or "suspicious" in front of the phrase "disease or injury". There are actually two branches of pathology: anatomic -- which deals with structural alterations of the human body; and clinical -- which deals with laboratory examination of samples removed from the body. Most forensic pathologists are experts in both branches.

Forensic Photography

Basic techniques of photography as they apply to investigative work. Photographs can be instrumental in recording the victim's lifestyle and personality; the topography and socioeconomic conditions surrounding the crime scene; and much more which is important to any investigator or analyst who is unable to visit the crime scene. If done properly, crime scene photography greatly assists the profiler in developing a psychological and behavioral profile of the offender. Types of items that are photographed at a crime scene are; Bullet casings; photograph as a group and photograph individually.  Photograph any dropped items, foot prints or animal tracks.  If a homicide, photograph the body or bodies.  Photograph any toolmarks, bitemarks or skin impressions. Imprint evidence requires extra measures.  Shoe imprints are photographed individually and as a series or group.  Shoe imprints need to be lit from the side to show as much detail in the imprint as possible.  Tire imprints are photographed from above as a whole.  If the tire imprint is four feet long, then a picture showing all four feet is taken.  Detail pictures are then taken showing one foot sections, each picture overlapping the one before it.  This way, specific detail can be show and the overlapping pictures lined up to show the whole print.  Again, all pictures are taken with and without a scale. Basically, anything that might be evidence is photographed. Video is also used to film crime scenes, taking long sweeping shots that take in everything in an unbroken time frame.  The problem with video is, camcorder microphones will pick up the officers talking in the background, which can sometimes be embarrassing when the tape is replayed in court.

Forensic Psychiatry and Profiling

The first category involves mental illness and disorder, what creates mental illness and disorder, and its diagnosis and treatment. The other category involves profiling, in which an investigator can examine certain crime scenes to come up with a personality profile of the offender. A forensic psychiatrist is a physician who integrates clinical experience, knowledge of medicine, mental health, and the neuroscience to form an independent, objective opinion. Relevant data is gathered and analyzed as part of a process of alternative hypothesis testing to formulate an expert medical/psychiatric opinion. Written report, deposition, or courtroom testimony can effectively communicate this expert opinion. The applications of forensic psychiatry are widespread in settings ranging from health care and the workplace to criminal justice and public safety.

Forensic Serontology

Determination of the type and characteristics of blood, blood testing, bloodstain examination, and preparation of testimony or presentations at trial are the main job functions of a forensic serologist, who also analyzes semen, saliva, other body fluids and may or may not be involved with DNA typing.

Forensic Toxicology

This generally concerns the detection and characterization of poisons or toxins exhibiting adverse physiological effects. Laboratory methods used in chemical toxicological analysis cover a wide range and may be broadly classified as follows: (1) physical tests (2) crystal tests (3) chemical spot tests (4) spectrophotometric tests (5) chromatographic tests.

Computer/Electronics Forensics

Computer forensics is simply the application of computer investigation and analysis techniques in the interests of determining potential legal evidence. Evidence might be sought in a wide range of computer crime or misuse, including but not limited to theft of trade secrets, theft of or destruction of intellectual property, and fraud. Computer specialists can draw on an array of methods for discovering data that resides in a computer system, or recovering deleted, encrypted, or damaged file information. Any or all of this information may help during discovery, depositions, or actual litigation.

DNA Forensic Analysis

DNA, or deoxyribonucleic acid, is the fundamental building block for an individual's entire genetic makeup. It is a component of virtually every cell in the human body. Further, a person's DNA is the same in every cell. For example, the DNA in a man's blood is the same as the DNA in his skin cells, semen, and saliva. This relies on one key characteristic of DNA: the configuration is the same in all cells of an individual. Altogether each person carries around 200,000 genes in each cell, comprising three billion base pairs -the chemical building blocks of DNA. Analyzing all these base pairs and genes in order to identify an individual would be impossible, with current technology. Instead, forensic scientists focus on certain genetic sequences called markers. Here, the arrangement of genetic information is highly variable and particular to each person.

DNA is contained in blood, semen, skin cells, tissue, organs, muscle, brain cells, bone, teeth, hair, saliva, mucus, perspiration, fingernails, urine, feces, etc.

CODIS (Combined DNA Index System), an electronic database of DNA profiles that can identify suspects, is similar to the AFIS (Automated Fingerprint Identification System) database.

DNA profiles are entered into the DNA database. Just as fingerprints found at a crime scene can be run through AFIS in search of a suspect or link to another crime scene, DNA profiles from a crime scene can be entered into CODIS. Therefore, law enforcement officers have the ability to identify possible suspects when no prior suspect existed.

Several factors can affect the DNA left at a crime scene, including environmental factors (e.g., heat, sunlight, moisture, bacteria, and mold). Therefore, not all DNA evidence will result in a usable DNA profile. Further, just like fingerprints, DNA testing cannot tell officers when the suspect was at the crime scene or for how long.

Fingerprint analysis

There are three basic fingerprint patterns: Loops, Arches and Whorls.  Everyone falls into one of these three patterns (diagram).  Within these patterns are what we call minutia points.  There are about thirty different types of minutae points, and no two people have the same types of minutae in the same number in the same places on their fingertips.  This is why our fingerprints are totally unique. Prints are left on a surface because we are constantly secreting water and body oils and other compounds through our pores.  This material is left on the surface we touch in the form of a fingerprint.   Different surfaces require different techniques for developing prints.  In the movies, you usually see detectives with brushes.  They are powder processing the prints.  Minute particles of powder cling to the print residue as the brush passes over it.  The print is then lifted with tape. Another process involves fuming.  Vapors of iodine and super glue (bonds in seconds) will coalesce inside the print residue to reveal a latent print. There are special processes that develop prints on paper, wood and cardboard.  Fingerprints can be developed on objects that have been in water.  Prints can be developed off of skin (such as from the neck of a strangulation victim).  There are very few surfaces on which a print cannot be developed.

Firearms and Toolmark Identification (Ballistics)

Firearm examination involves the identifying characteristics between firearm and projectile, projectile and target. Typically, this includes matching bullets to the gun that fired them. Tool mark identification involves the identifying characteristics between tools, such as a pry bar, and the object on which it is used, such as a doorframe. Also included in the category are explosives and imprint evidence. Ballistics falls under multiple titles, including the study of firearms, the study of projectiles, the study of firing characteristics of a weapon, and wound ballistics (see this last one below!). Within these categories are more: interior ballistics, exterior ballistics, and terminal ballistics

Imprint and Impression Evidence

Criminalists who specialize in impression evidence are concerned with various types of two-or-three dimensional markings such as footwear impressions, tire impressions and footprints. Evidence impression marks are compared with known markings made by the object suspected of causing the imprint or impression. Some types of impression evidence such as fingerprints and tool marks fall within the province of other subspecialties discussed above.

Questioned Document Examination
Concerned with identification of handwriting and technical aspects of document preparation. This includes forgery, counterfeiting, handwriting analysis and other related sub disciplines.

Handwriting analysis looks at letter formations, connecting strokes between the letters, upstrokes, retraces, down strokes, spacing, baseline, curves, size, distortions, hesitations and a number of other characteristics of handwriting.  By examining these details and variations in a questioned sample and comparing them to a sample of known authorship, a determination can be made as the whether or not the authorship is genuine

Typewriting analysis is a review of individual characteristics which are either inherent in the machining process of a manufactured item, or come about through the wear and tear in the use of an object.  It is these individual characteristics that allow for the identification of an object to the exclusion of all others of its general type. As with typewriters, all typewriters of a particular make and model are pretty much the same but, through use, the develop defects that translate to paper when the machine is used.  These defects on the typed page can be matched back to the typewriter that was used to create it. These defects in the type face are revealed in a number of ways.  If the type bar is bent (the bar on which the letter element is attached and hammered down to the page) the letter is misaligned or 'off its feet.'  Misalignments can also cause non printing areas of a specific letter, such as losing the loop on the bottom of a 'g.'  The letter can be displaced horizontally or vertically.  Little clumps of plastic can adhere to the type key during manufacture and are made permanent by the coating process (called flashing).

Photocopier and Laser Printer analysis yields many ways to match a page back to a photocopier or laser printer. Since the processes are similar, the methods used  to match a page back to its origin, printer or copier, will also be similar. The paper itself can yield many clues.  Look for marks from the belts, pinchers, rollers and gears that physically move the paper through a machine. Toner can have unique characteristics in its chemical composition.  Also, look at how the tone was placed on and fused to the paper.  Toner may clump up on the drum, transferring blobs of toner at a time to the printed page.  Marks on the optics (glass platen, lenses, mirrors) used to transfer or create an image on paper might contain unique defects (such as scratches) that will render anomalous markings on the printed page.