In a nutshell, forensics is the application of science which includes physical, medical, and behavioral science as it relates to the law. Scientific procedures and equipment are used in investigating offsets as well as convicting the defender in court.
There are many sub disciplines in forensic science, but the most common are physical science and medical science.
Of all the physical sciences, chemistry and physics are the two categories of physical science that apply the most to forensics. Chemical analysis is important in examining the nature of trace evidence . Trace evidence refers to very small physical matter (such as cloth fiber, a hair, or shards of glass) that provides evidentiary value. Chemical analysis is also used to examine questioned documents . Questioned documents are any documents that are related to the commission of a crime. This terminology many times is applied to suspected forgeries such as counterfeit money or documents that have been unlawfully altered such as the changing of the value of a check. Forensic scientists such as chemists or document analysts many times scrutinize documents with the hope of identifying the kind of ink or paper used in order to help identify the perpetrator who orchestrated the manufacture of the fake document.
Physics is useful in forensics because it can be used to determine the original location of a resultant blood spatter in the event of a shooting. Physics can also be used to examine the trajectory of a bullet in an assassination.
Crimes such as rape leave behind biological evidence such as fluid or traces of soft tissue whereas homicides leave behind corpses. In the event of a rape, fluid and soft tissue passages are the focus of an investigation for a medical scientist such as a forensic medical examiner. For the victims of a homeless, it is up to the medical scientist to dig for information by performing an autopsy with the hope that evidence will show up in the corpse to help bring an offender to justice.