Forensic Science

The first recorded use of forensic science to prove guilt comes from medieval China in 1325. A farmer was murdered in his field by a sickle (a common harvesting tool). 

Investigators gathered all the sickles and laid them out. One attracted flies, proving it was used in the murder.

In 1784 forensic science was used to solve the murder of a maid. Investigators matched a crumpled piece of paper that was used to secure gunpowder with a piece of paper found in the suspect’s pocket. 

Toxicologists need to understand how each poison can affect people of different sizes, ages and health.  

Drug use as well as the use of a slow acting poison can be detected by toxicologists. Hair examined under a microscope can tell investigators whether it was naturally shed or pulled out.

The most important part of collecting trace evidence is to first photograph the scene in situ (on site). Once the site is recorded evidence can be taken away for laboratory analysis.

Investigators will study the car's lights to determine if they were on at the time (in the case of headlights), whether brake lights were applied, or whether a turning signal was on (by studying indicator lights).

One of the most well known type of trace evidence are fingerprints. Unique to an individual fingerprints can definitively link a person to a scene.

DNA is a molecule that contains all of an individual's genetic information. DNA is contained in every part of the body including blood, saliva, sweat, mucus, earwax, hair and skin cells. If any bodily material is found at a crime scene DNA information can usually be extracted.

There are a number of methods used to extract the DNA from the evidence. DNA can be extracted from cigarette butts, drinking glasses, doorknobs and clothing.

Forensic entomologists understand in great detail the relationship between a deceased human and the insects that feed on the remains. There is a particular order in which each species begins to feed and/or breed on remains. 

Understanding which species arrive when can determine the approximate time of death.

The surprising presence of a spider or a bee in a moving vehicle is believed to be one of the top 20 reasons for car accidents. Forensic entomologists are also sometimes called in to examine squashed insects located on a car to determine the car’s probable path. 

All branches of forensic science begins by collecting photographic evidence of the scene as it was found by investigators. These photos will be used by fire investigators to study burn and smoke patterns. 

Burn patterns are also used to determine whether accelerants were used increase the fire’s spread or ferocity. A ‘u’ shaped pattern can suggest a pool of accelerant was used to start the fire.