Little Known Facts and Common Perceptions About Forensic Science

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• The term “forensic” is derived from the Latin word “forensis,” which comes from the word “forum.” A forum was a public place in Rome where the courts heard trials and orations were delivered, hence its usage today as meaning belonging to or used in a court of law. Forensic science is any science applied to the law or to legal questions.
• The best source of the genetic material DNA is the cell nucleus. Red blood cells do not have a nucleus, thus they are not a good source of DNA
• A single strand of hair can provide a wealth of information to a scientist who knows how to interpret it. However, it is not possible to tell if a hair came from a man or a woman unless the root of the hair is still attached, thus providing DNA, which can provide information about gender.
• Handwriting analysis is based on the premise that every person has a unique style of writing. This style changes over time. For these reasons, a visual comparison of two writing samples can yield information about signature fraud and the approximate date of a writing sample. Infrared light can often demonstrate differences between two types of ink. The markings left by the pen also enable an analyst to differentiate between two samples of writing.
• Alec Jeffreys, and English geneticist, was the first to develop a technique to use DNA for identification purposes. The technique Jeffreys developed enabled the comparison of DNA from the crime scenes where two young girls who were murdered in England in 1983 and 1987 to that of possible suspects. DNA analysis first proved that the main suspect in the case was innocent. Later, the perpetrator, who knew he would be proven guilty with the DNA evidence, confessed to both murders. Blood samples were taken and the DNA from the crime scenes matched the samples.
• Many important pieces of data can be gathered from a human skeleton. Gender can be determined from the bone structure. In particular the pelvic bones differ between men and women. Occupation can frequently be determined because most occupations leave evidence of typical activity on the bones. The most obvious cases occur in persons who were employed as heavy laborers. Disease and sickness also leave evidence on the bones of the afflicted, sometimes even deformities. Intelligence cannot be determined from skeletal remains. Many people believe that skull size is an indicator of intelligence, but this is a myth.
• Victims of fires and explosions are most commonly identified by their dental records. Teeth are very useful in victim identification because they decay much more slowly than bones. Also, the teeth can withstand extreme temperatures that bones cannot. Thus, they are often found even after a victim dies in a fire or explosion.
• Henry Jackson was a burglar in Great Britain. During a robbery in 1902, he placed his hand in wet paint, leaving his fingerprints. His case was the first in which an individual was convicted of a crime based on print evidence.
• The Federal Bureau of Investigation (FBI) Laboratory provides analysis of physical evidence and testimony on findings. The Laboratory also serves as a leader in the development of new technology and technological support. To read more about the FBI Laboratory, click here.
• In 1985, the Bureau of Alcohol, Tobacco and Firearms (ATF) and several other agencies (the Portland Fire Bureau and the Connecticut State Police) teamed up to train new K-9 units in the arson dog program. These dogs are trained to detect accelerants that are often used by arsonists to start fires. The dogs are better at the detection of the accelerants than the electronic detection devices used by human investigators. Their reward? Some are rewarded with food and some are paid in toys such as tennis balls.
• Most professionals agree that if a person knows that they are telling a lie, it can be detected by the polygraph. The polygraph measures the physiological arousal that occurs when people lie. Thus, the theory goes, a person could only “beat” the test if they are telling a lie that they believe to be the truth. Polygraphs are admissible in court if the judge allows the evidence. The US Supreme Court has not yet ruled on the admissibility of polygraph evidence, thus the admissibility varies by state.
• A professional working in the medicolegal area of forensic entomology studies arthropods in order to establish how long a body has been dead or if a body has been moved. Arthropods feed on dead vertebrates and their life cycles are consistent. This makes it possible for an entomologist to determine the length of time a body has been dead. To learn more about the profession of forensic entomology, click here.
• Ballistics experts are able to determine of a person was present when a crime involving a gun was committed by examining the residue samples from the suspect’s skin. The sample from the individual who fired the gun will contain primer residue and gunpowder. The gunpowder and primer contain lead antimony and barium, chemicals which can be detected in the lab. To learn more about ballistics experts click here.
• Locard’s principle is used in crime scene investigations because each individual who is present at a crime scene leaves some evidence of their presence. Each person will also take some evidence from the crime scene. This evidence may not always be detected, because it is often minute, but it does exist.
• Vegetable, mineral, animal, and man-made are the only four types of fibers that exist. The analysis of these fibers compares characteristics of the fibers such as color type, coarseness, diameter, discoloration and cross-sectional shape. The color of the fiber is by far the most important characteristic. It is analyzed using a microspectrophotometer, and is the equivalent of a fingerprint of the fibers. Using this technique, fibers of the exact same color can be matched.
• Eyewitness testimony is actually often unreliable. The reasons for the inaccuracies are many, but include the witness’s relationship with the accused, the amount of time that passes between an offense and the identification of the suspect and the nature of the offense as perceived by the witness. False identification is the explanation for most of the cases in which innocent persons are convicted. Nonetheless, eyewitness accounts are still considered by many laypersons, even those on a jury, to be a convincing piece of evidence. They also believe that inaccuracies can be easily detected.

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