Forensic science, also known as criminalistics, is the application of science principles and methods to support legal decision-making in matters of criminal and civil law.
Rigor mortis, or postmortem rigidity, is the fourth stage of death. It is one of the recognizable signs of death, characterized by stiffening of the limbs of the corpse caused by chemical changes in the muscles postmortem. In humans, rigor mortis can occur as soon as four hours after death. Contrary to folklore and common belief, rigor mortis is not permanent and begins to pass within hours of onset. Typically, it lasts no longer than eight hours at "room temperature".
Livor mortis, postmortem lividity, hypostasis or suggillation, is the second stage of death and one of the signs of death. It is a settling of the blood in the lower, or dependent, portion of the body postmortem, causing a purplish red discoloration of the skin. When the heart stops functioning and is no longer agitating the blood, heavy red blood cells sink through the serum by action of gravity. The blood travels faster in warmer conditions and slower in colder conditions.
Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is essential for recycling the finite matter that occupies physical space in the biosphere. Bodies of living organisms begin to decompose shortly after death. Animals, such as earthworms, also help decompose the organic materials. Organisms that do this are known as decomposers or detritivores. Although no two organisms decompose in the same way, they all undergo the same sequential stages of decomposition. The science which studies decomposition is generally referred to as taphonomy from the Greek word taphos, meaning tomb. Decomposition can also be a gradual process for organisms that have extended periods of dormancy.
Putrefaction is the fifth stage of death, following pallor mortis, livor mortis, algor mortis, and rigor mortis. This process references the breaking down of a body of an animal post-mortem. In broad terms, it can be viewed as the decomposition of proteins, and the eventual breakdown of the cohesiveness between tissues, and the liquefaction of most organs. This is caused by the decomposition of organic matter by bacterial or fungal digestion, which causes the release of gases that infiltrate the body's tissues, and leads to the deterioration of the tissues and organs. The approximate time it takes putrefaction to occur is dependent on various factors. Internal factors that affect the rate of putrefaction include the age at which death has occurred, the overall structure and condition of the body, the cause of death, and external injuries arising before or after death. External factors include environmental temperature, moisture and air exposure, clothing, burial factors, and light exposure. Body farms are facilities that study the way various factors affect the putrefaction process.
The post-mortem interval (PMI) is the time that has elapsed since an individual's death. When the time of death is not known, the interval may be estimated, and so an approximate time of death established. Postmortem interval estimations can range from hours, to days or even years depending on the type of evidence present. There are standard medical and scientific techniques supporting such an estimation.
A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSI) and law enforcement. The location of a crime scene can be the place where the crime took place or can be any area that contains evidence from the crime itself. Scenes are not only limited to a location, but can be any person, place, or object associated with the criminal behaviours that occurred.
Bloodstain pattern analysis (BPA) is a forensic discipline focused on analyzing bloodstains left at known, or suspected crime scenes through visual pattern recognition and physics-based assessments. This is done with the purpose of drawing inferences about the nature, timing and other details of the crime. At its core, BPA revolves around recognizing and categorizing bloodstain patterns, a task essential for reconstructing events in crimes or accidents, verifying statements made during investigations, resolving uncertainties about involvement in a crime, identifying areas with a high likelihood of offender movement for prioritized DNA sampling, and discerning between homicides, suicides, and accidents.
Crime reconstruction or crime scene reconstruction is the forensic science discipline in which one gains "explicit knowledge of the series of events that surround the commission of a crime using deductive and inductive reasoning, physical evidence, scientific methods, and their interrelationships". Gardner and Bevel explain that crime scene reconstruction "involves evaluating the context of a scene and the physical evidence found there in an effort to identify what occurred and in what order it occurred." Chisum and Turvey explain that "[h]olistic crime reconstruction is the development of actions and circumstances based on the system of evidence discovered and examined in relation to a particular crime. In this philosophy, all elements of evidence that come to light in a given case are treated as interdependent; the significance of each piece, each action, and each event falls and rises on the backs of the others."
Forensic biology involves the application of biological principles and techniques within the context of law enforcement investigations.
Cadaveric spasm, also known as postmortem spasm, instantaneous rigor mortis, cataleptic rigidity, or instantaneous rigidity, is a rare form of muscular stiffening that occurs at the moment of death and persists into the period of rigor mortis. Cadaveric spasm can be distinguished from rigor mortis as the former is a stronger stiffening of the muscles that cannot be easily undone, while rigor mortis can.
Forensic photography may refer to the visual documentation of different aspects that can be found at a crime scene. It may include the documentation of the crime scene, or physical evidence that is either found at a crime scene or already processed in a laboratory. Forensic photography differs from other variations of photography because crime scene photographers usually have a very specific purpose for capturing each image. As a result, the quality of forensic documentation may determine the result of an investigation; in the absence of good documentation, investigators may find it impossible to conclude what did or did not happen.
The following outline is provided as an overview of and topical guide to forensic science:
Odell Barnes Jr. was a Texas man convicted of the 1989 murder of Helen Bass. During the later stages of Barnes' legal appeals, human rights groups and anti-death penalty advocates raised questions about Barnes' murder conviction, leading to international media attention and diplomatic protests from the government of France. Barnes was executed on March 1, 2000.
Rape investigation is the procedure to gather facts about a suspected rape, including forensic identification of a perpetrator, type of rape and other details.
Investigating Innocence is a nonprofit wrongful conviction advocacy organization that provides criminal defense investigations for inmates in the United States. Investigating Innocence was founded in 2013 by private investigator Bill Clutter to assist nationwide Innocence Project groups in investigating innocence claims. "Once we have a case that meets our criteria, we'll put private investigators to work on it. A lot of these cases need investigators," said Kelly Thompson, executive director of Investigating Innocence. Prior to his work on Investigating Innocence, Clutter was one of the founders of the Illinois Innocence Project. Investigating Innocence also has a board composed of exonerees that reviews incoming cases.
Post-mortem chemistry, also called necrochemistry or death chemistry, is a subdiscipline of chemistry in which the chemical structures, reactions, processes and parameters of a dead organism is investigated. Post-mortem chemistry plays a significant role in forensic pathology. Biochemical analyses of vitreous humor, cerebrospinal fluid, blood and urine is important in determining the cause of death or in elucidating forensic cases.
Ludwig Tessnow was a German serial killer known as the Monster of Rügen and the Mad Carpenter of Rügen, who murdered four prepubescent children in two separate attacks in 1898 and 1901.
Evidence packaging involves the specialized packaging methods and materials used for physical evidence. Items need to be collected at a crime scene or a fire scene, forwarded to a laboratory for forensic analysis, put in secure storage, and used in a courtroom, all while maintaining the chain of custody. Items might include DNA, drugs, hair samples, body parts, blood samples, sperm, knives, vomit, firearms, bullets, fire accelerants, computers, checkbooks, etc.
The stages of death of a human being have medical, biochemical and legal aspects. The term taphonomy from palaeontology applies to the fate of all kinds of remains of organisms. Forensic taphonomy is concerned with remains of the human body.
