Investigations.

1.-Forensic medicine, 

the science that deals with the application of medical knowledge to legal questions.

• 

  A forensic anthropologist examining a cranium exhumed from a mass grave. The work was conducted as …

  Marco Di Lauro/Getty Images

The use of medical testimony in law cases predates by more than 1,000 years the first systematic presentation of the subject by the Italian Fortunatus Fidelis in 1598. Forensic medicine was recognized as a specialty early in the 19th century.

The primary tool of forensic medicine has always been the autopsy. Frequently used for identification of the dead, autopsies may also be conducted to determine the cause of death. In cases of death caused by a weapon, for example, the forensic pathologist—by examining the wound—can often provide detailed information about the type of weapon used as well as important contextual information. (In a death by gunshot, for example, he can determine with reasonable accuracy the range and angle of fire.) Forensic medicine is a major factor in the identification of victims of disaster, such as landslide or plane crash. In cause-of-death determinations, forensic pathologists can also significantly affect the outcome of trials dealing with insurance and inheritance.

In the 19th century, two other forensic specialties arose, namely, forensic psychiatry (which is used to determine the mental health of an individual about to stand trial, and, thus, his blameworthiness) and forensic toxicology. The forensic toxicologist gives evidence on such topics as intentional poisonings and drug use. The toxicologist has played an increasingly important role in matters of industrial and environmental poisoning.

2.-Brain structure and function

The amygdala — a part of the brain involved in fear, aggression and social interactions — is implicated in crime. Among the research that points to this link is a neuroimaging study led by Dustin Pardini, PhD, of the University of Pittsburgh. His team found that 26-year-old men with lower amygdala volumes were more than three times more likely to be aggressive, violent and to show psychopathic traits three years later than men of the same age with more normal-sized amygdalas — independent of factors including history of violence and social background (Biological Psychiatry, 2013).

Other research, such as an fMRI study led by psychologist Andrea Glenn, PhD, of the University of Alabama, suggest that amygdala functioning — not just size — is also more likely to be reduced among those with psychopathic tendencies (Molecular Psychiatry, 2009).

At least one study indicates that such deficits may appear long before people commit crimes. Adrian Raine, DPhil, of the department of criminology at the University of Pennsylvania, led a study with Yu Gao, PhD, at CUNY-Brooklyn that examined fear conditioning, which is dependent on amygdala function, in a group of 1,795 3-year-olds. The researchers put electrodes on the children's fingers while repeatedly playing two tones: one that was followed by a loud, unpleasant sound and another that was played alone. Subsequently, the difference in sweat responses to each tone by itself yielded a measure of each toddler's fear conditioning. Twenty years later, the team identified participants who had gone on to commit crimes and compared them with noncriminal counterparts, matching them on gender, ethnicity and social adversity. They found that those children who went on to commit crimes had "simply failed" to demonstrate fear conditioning, Raine says. In other words, they were fearless when most of us would be fearful. This finding suggests that deficits in the amygdala, which are indirectly identifiable as early as age 3, predispose to crime at age 23 (The American Journal of Psychiatry, 2010).

The anterior cingulate cortex (ACC), which plays a major role in behavior regulation and impulsivity, has also been linked to crime. Psychologist Kent Kiehl, PhD, and colleagues at the University of New Mexico used fMRI to look at the brains of nearly 100 adult male inmates while they completed a cognitive task involving inhibitory control. They found that prisoners with lower ACC activity were twice as likely to reoffend four years after they left prison than prisoners with higher ACC activity (PNAS, 2013). While such studies need replication and extension, Raine says, they are "proof of the concept that there may be added value with bringing on board neurobiological information, including brain imaging information, for future prediction of violence."

3.- The Crime Scene Investigator or Evidence Recovery Technician

In the Scientific community the crime scene investigator or evidence recovery technician is accepted as a forensic specialist. His/ Her specialty is considered a professional organized step by step approach to the processing of a crime scene. Extensive study, training, and experience in crime scene investigations is needed for the investigator to be proficient in the field. He/she must be well versed in all areas of recognition, documentation and recovery of physical evidence that may be deposited at the scene. A general knowledge of what analysis may be performed in the lab as well as proper procedures in handling, collecting and packaging of items of evidence is needed to assure those recovered items will safely arrive at the lab.