The word Forensic comes from the Latin forensus, meaning of the forum. In ancient Rome, the forum was where lawmaking debates were held, but it was also where trials were held just like modern day courthouses. From that, forensic science has come to mean the application of the natural and physical science to the motion of matters within a legal context.

Forensic Science can be viewed as a tripartite structure consisting of a Collection, which pertains to the science investigation, Examination, which pertains to the medical investigation and, Presentation, which pertains to the courts. A forensic case will involve all aspects of each of the three structured elements, each being as important as the other. It is obvious that there needs to be a shared approach for the successful end of each case. Each step in forensic science must be done in an exact order; therefore it can be assured that the investigation can have few doubts about what is being debated.

The purpose of crime scene investigation is to help establish what happened at the crime and to identify the responsible person or people. Carefully documenting the situation at a crime scene and recognizing all-important physical evidence do this. The ability to recognize and properly collect physical evidence is often times vital to both solving and prosecuting violent crimes. It is no exaggeration to say that in the majority of cases, the law enforcement officer who protects and searches a crime scene plays a significant role in determining whether physical evidence will be used in solving or prosecuting violent crimes.

Documenting a crime scene and its conditions can include directly recording brief details such as lighting, furniture, fingerprints, and other valuable information. Certain evidence if not collected right away can easily be lost, destroyed or ruined. The range of investigations can also expand to the fact of dispute in such cases as suicide or self-defense. It is also important to be able to recognize what should be present at a crime scene, what to look for at a crime scene and what might appear out of place. A crime scene often does not relate to the direct area in which a victim or actual crime has occurred, but the possibility of escape or access routes should also be checked. Anything, which can be used to connect a victim to a suspect or a suspect to a victim or a crime scene, is important physical evidence. Richard Saferstein explains, Physical evidence encompasses any and all objects that can establish that a crime has been committed or can provide a link between a crime scene and its victim or a crime and its perpetrator.
One of the first things an officer should do once he gets to the crime scene is to take control and secure the scene as quickly as possible. This is to prevent anyone from ruining evidence and to keep unauthorized person or persons out of the area such as the media, the public or anyone who doesn't belong. While this is being done, an officer should also be alert for useless evidence and note if there are any possible approach or escape routes. After an officer does this, he should conclude the degree in which the scene has been protected and make sure there is enough security in the area. All persons entering and exiting the crime scene should be logged and kept down to a bare minimum to make sure the purity of the crime scene when the case goes to court. Each person involved in the crime scene should have knowledge relative to its original conditions to avoid from accidental movement of objects, evidence or anything, which might hurt in the investigation of the crime. When all of this is done, the next step that can occur is the actual inspection of the crime scene.