Pathology

Forensic pathology is a subspecialty of pathology focused on examining persons who die suddenly, unexpectedly, or violently. [1] Forensic pathologists are experts in determining the cause and manner of death. [1] They are specially trained to perform autopsies to determine the presence or absence of disease, injury, or poisoning; to evaluate historical and law-enforcement investigative information relating to the manner of death; to collect medical evidence, such as trace evidence and secretions, to document sexual assault; and to reconstruct how a person received injuries. [1]

Cause and Manner of Death

The cause of death is divided into primary and secondary causes. The primary cause of death is the immediate cause of death, while secondary causes of death are conditions that are not related to the primary cause but contribute to the individual's death. [2] The manner of death refers to how the cause of death came about. [2]

There are five manners of death:

  • Homicide: The action of one person directly causing the death of another. [3, 4]

  • Natural Causes: Death solely by disease or a natural process. [5]

  • Accidental: An unnatural death resulting from an inadvertent chance happening. [5]

  • Suicide: Death from self-inflicted injury with evidence of intent to die. [5]

  • Undetermined: Used in very rare occasions, such as some unexpected infant deaths not classified as natural (SIDS) when an unsafe sleeping environment is present. [3, 5]

Mechanisms of death are the actual physical, physiological, or chemical events that bring on the cessation of life. [6, 7] For instance, a heart attack is a cause of death, while cardiac arrhythmia or cardiogenic shock are potential mechanisms of death. [7]

Medical Examiners vs. Coroners

About half of the U.S. uses a coroner system, while the other half uses a medical examiner system. [8] Coroners are usually elected officials (sometimes the sheriff), and formal education or medical training is not normally required. [8, 9] In a minority of states, the coroner must be a physician. [8] Medical examiners, on the other hand, must be physicians and are usually appointed by the government. [8] Some states have a mixture of coroners and medical examiners. [9]

The position of coroner originated in England in the early 1100s. [8] Initially, coroners were judicial officers tasked with collecting monies due to the king, trying felony cases, and investigating unusual, untimely, or suspicious deaths. [10] By the 13th century, coroners had to examine all bodies before burial and appraise all wounds. [10] The first coroner and medical examiners in the U.S. were appointed in the Maryland colony in 1637. [10] The first medical examiners in the U.S. were two physicians appointed in Baltimore in 1890. [10]

Autopsies

An autopsy, which means "to see with one's own eyes," is a standardized dissection of a corpse to determine the cause and manner of death. [11, 12] Autopsies are normally performed in cases of sudden, unexpected, violent, unattended, or suspicious deaths. [13] Medicolegal autopsies account for approximately one-third of all autopsies. [13]

There are two main types of autopsies:

  • Clinical: Carried out to diagnose the disease that caused death when antemortem efforts have failed. [14]

  • Medicolegal: Performed to provide answers to questions about the identity, cause of death, time of death, and circumstances surrounding death and to help law enforcement agencies solve crimes. [14]

The autopsy process involves:

  • External Examination: The entire body is examined, and all wounds and trauma are noted. The body is photographed clothed and unclothed. [12, 15]

  • Internal Examination: Incisions are made to the torso. Body fluid samples are taken, major organs are removed and weighed, and wounds are assessed. External objects that may have caused death are removed. X-rays may be taken. [15, 16]

Postmortem Interval (PMI)

The postmortem interval (PMI) is the estimated time since death. [17, 18] The principle of sequential changes that occur following death, called the postmortem clock, is used to determine PMI. [18, 19]

Several factors can be used to estimate PMI, including:

  • External examination: Temperature, livor mortis, rigor mortis, and decomposition [18, 19]

  • Chemical changes in body fluids or tissues: Potassium levels, metabolites in the brain, and film over the eye [20]

  • Physiological changes: Progression of digestion [18, 19]

  • Survival after injuries: Based on the nature, severity, and factors such as blood loss [18, 19]

  • Stomach contents: Can be used to estimate PMI, as it takes 2-4 hours to digest a meal [20, 21]

  • Insect activity: The presence of insects and their developmental stage can be used to estimate PMI. (This was discussed in detail in our conversation about forensic entomology.)

Types of Trauma

Traumatic deaths can be classified into four main categories:

  • Mechanical Trauma: Occurs when the force applied to a tissue exceeds its mechanical or tensile strength. [22] This includes sharp force injuries (e.g., stab wounds), blunt force injuries (e.g., being struck with a blunt object), and gunshot wounds. [23, 24]

  • Chemical Trauma: Results from interactions of chemicals with the human body. [22] This includes deaths from poisoning, drug overdoses, and acid or alkali burns. [25]

  • Thermal Trauma: Includes both hypothermia (exposure to extreme cold) and hyperthermia (exposure to extreme heat). [22]

  • Electrical Trauma: Death can occur due to electrocution, which can cause ventricular fibrillation (uncontrollable quivering of the heart) or severe burns and cellular damage. [22, 26]

Other Evidence Collected During Autopsy

  • Swabs: Taken for submission to forensic or toxicological laboratories. [27]

  • Hairs: Head and pubic hairs are collected. [27]

  • Ligatures: Extensively photographed, sketched, and collected. [27]

  • Fingerprints: A full set is taken for comparison against databases. [27]

  • Jaw: May be used for forensic dental examination and identification in cases of badly decomposed remains. [27]

Exhumations

Exhumation is the digging up or removing of a deceased individual from a burial site or mausoleum. [28] Exhumations may be necessary if questions about the cause or manner of death arise after burial. [29] However, embalming can complicate exhumations as it can obscure or obliterate details that might otherwise be easily examined. [28]

Consultations

Forensic pathologists may consult with other forensic specialists, such as forensic anthropologists, entomologists, and odontologists, in challenging cases involving burned, decomposed, or dismembered bodies. [29]

Additional Information

The sources provide detailed information on specific topics within forensic pathology, such as the characteristics of gunshot wounds, the stages of decomposition, and the effects of different drugs on the body. You can refer to the sources for more detailed information on these topics.