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.

Preservation and contamination

214px|thumb|Police investigating the scene of a [[gang-related shooting in Los Angeles, California in October 2008]]

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.

Sequence of events

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.

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.

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. Different types of evidence will sometimes need different methods of collection or specific containers. For instance, paper containers, such as bags, envelopes, or boxes, may be optimal for biological samples. Paper containers allow evidence that is not completely dry to continue drying. Fingerprint collection through the use of grey or black magnetic powder. DNA and other bodily fluids are collected and, whether it is hair or fluid, for further examination in a lab. Fingernails are also part of evidence collection because they have striations on them which are individual characteristics. Fingernails should be collected and placed in a paper packet then placed in a paper envelope and labelled for processing.

Indoor crime scenes have a significantly lower chance of contamination because of the lack of exposure. The contamination here usually comes from the people factor. Conveyance crime scenes are crimes committed utilizing transportation, such as robbery, grand theft, carjacking, sexual battery, and homicide.

See also

  • Crime scene cleanup
  • DNA analysis
  • Evidence management
  • Forensic analysis
  • Forensic science
  • Forensic photography
  • Law enforcement
  • Problem property

References

  • https://web.archive.org/web/20140221230759/http://www.nfstc.org/pdi/Subject01/pdi_s01_m01_04.htm
  • http://www.evidencemagazine.com/index.php?option=com_content&task=view&id=184