The purpose of conducting a crime scene investigation is basically to find out what happened. Crime scene investigations are conducted whenever a crime, such as a burglary or murder has occurred. They are conducted by well trained law enforcement personnel. A few of their primary goals are to prevent contamination of the crime scene, gather evidence and interview people involved or witnesses to the crime.
Criminal investigators need to be experts at their job. There have been instances where there has been contamination of a crime seen. Evidence was mishandled and dangerous criminals have been set free due to lack of evidence.
Crime scene investigation entails law enforcement officers responding to the scene of a crime to help victims, secure the area, preserve and collect evidence, and interview witnesses. The first concern is the safety of citizens that may be in or near the crime scene. This of course assumes that someone is at the crime scene. Law enforcement officers also want to secure the area to prevent further crimes being committed and to preserve the condition of the scene. Preservation of the scene is a critical step in the investigation of the crime. The collection of evidence that may still be at the scene is also important to document findings that will be used at a later date.This evidence may prove helpful in finding the perpetrator of the crime. Lastly, if any witnesses remain at the location, they can provide valuable information that may also help in the investigatory process.
It is an immensely popular TV show in the US, but it also describes the process that the police forensic scientists go through in order to try and determine what happened at a crime scene according to clues left either by the perpetrator or other clues that were left behind.
Crime scene investigation is a part of most of the branches of law enforcement including the police, the FBI, the CIA even, and many other groups.
The idea comes from a more broad branch of science called "forensic science" which tries to determine things about a phenomenon or an event by clues that are left behind. A forensic pathologist attempts to reconstruct what happened because of a particular disease by the clues that are left in the body. A forensic engineer attempts to determine what went wrong in a building or other structure by investigating the remains.
A crime scene forensic officer does the same thing for a crime scene.