A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSI) and law enforcement. The location of a crime scene can be the place where the crime took place or can be any area that contains evidence from the crime itself. Scenes are not only limited to a location, but can be any person, place, or object associated with the criminal behaviours that occurred.

Immediately after the discovery of a crime scene, measures must be taken to secure and protect the scene from contamination. To maintain the integrity of the scene, law enforcement must take action to block off the surrounding area as well as keep track of who comes in and who goes out. By taking these precautions, officers can ensure that evidence that is collected can be used in court. Evidence that has become contaminated, tampered with, or mistreated can pollute the scene and cause a case to be thrown out of court.

Everything that occurs during the analysis of a scene must be documented. It is the job of the initial responding officer to make sure that the scene has an extremely coherent and summarized documentation. The documentation should include the officer's observations and actions while at the scene. The initial responder is in charge of documenting the appearance and condition of the scene upon arrival. The initial responder will also gather statements and comments from witnesses, victims, and possible suspects. Several other documents are also generated so that a crime scene's integrity is kept intact. These documents include a list of who has been in contact with evidence (chain of custody), as well as a log of what evidence has been collected.

A crime scene is often preserved by setting up a blockade to control the movement in and out of a scene as well as maintaining the scene's integrity. A perimeter is taped off with barricade tape in order to keep only those necessary on-site. This is done to prevent contaminated evidence as investigators try to avoid contamination at all costs. While it is difficult to completely avoid contamination, many steps are taken to ensure the integrity of the crime scene remains intact. Officers take care to not eat, drink, smoke, or take their breaks near the crime scene. Anything leftover by the officers on the scene could be mistaken for potential evidence and tamper with the success of the investigation.

The Initial Responding Officer receives a dispatch call and arrives at the location of the crime. This officer plays a crucial part in maintaining the integrity of the scene. Initial responders are in charge of securing the scene by setting up physical barriers to control the traffic in and around the area. The officer also documents his/her initial observations, as well as the condition of the scene upon arrival. Once the crime scene investigation unit, arrives on the scene, being sure not to touch anything, an initial walkthrough is performed. This walkthrough helps the investigators get an understanding of what kind of crime has occurred. The unit notes on the presence of potential evidence and devises a plan for processing the scene.

A second walkthrough is performed for the purpose of documentation. The unit will take pictures and draw sketches of the scene. Sometimes videos are taken to ensure every detail of the crime is documented. After thorough documentation has been conducted, the CSI unit carefully collects all items that could be considered the evidence. These items are tagged, logged, and packaged to ensure nothing is damaged or lost. All evidence from the scene is sent to the forensic laboratory for analysis. The forensic laboratory processes all pieces of evidence from the scene. Once the results are in they go to the lead detective on the case.

Photographs of all evidence are taken before anything is touched, moved, or otherwise further investigated. Evidence markers are placed next to each piece of evidence allowing for the organization of the evidence.

Sketching the scene is also a standard form of documentation at a crime scene. Crime scene sketches allow for notes to be taken as investigators may take measurements and other data that may not be easily detected from only a photograph. The investigators will draw out locations of evidence and all other objects in the room. The sketch is usually drawn from an above point of view. Notes are taken by investigators to ensure the memorization of their thoughts and suspicions about different pieces of evidence.