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What are the Parts of a Crime Scene Investigation?

S. Zaimov
S. Zaimov

Crime scene investigation (CSI) is the process in which the physical evidence from a crime scene is gathered. Its primary purposes are to identify the victim and possible suspects, carefully collect evidence that suggests how the crime was committed and prepare the evidence for presentation in a court. Experts in different fields are typically employed to make sure the gathered information is truthful and has not been tampered with.

Before the crime scene investigation unit can document a scene, the police typically secure the area and make sure there is no outside interference. If the evidence requires special analysis, a specialist in the field of forensic science may be called to the site. Homicides usually require a medical examiner to determine the cause of death, but sometimes laboratory tests are needed to be certain of it. Detectives are also usually on the scene to start putting the events of the crime together, which commonly includes interviewing witnesses and consulting with the CSI unit.

Crime scene investigation involves gathering evidence at the scene of the crime.
Crime scene investigation involves gathering evidence at the scene of the crime.

The investigation process must be conducted with extreme care and close attention to detail. With this in mind, the investigators' first step is usually identifying the boundaries of the entire scene and exploring all possible places for clues. Investigators then walk through the scene carefully, to avoid changing anything since the crime was discovered. The site is then documented, which typically involves making drawings or taking pictures or video. Only during the subsequent collecting of evidence are items from the scene actually touched. When collecting evidence, it is carefully tagged and preserved.

Evidence left behind at a crime scene, like latent fingerprints, can be collected and used to implicate a suspect.
Evidence left behind at a crime scene, like latent fingerprints, can be collected and used to implicate a suspect.

Many different types of clues may be found, depending on the nature of the crime. For example, if a murder has taken place, the exact position of the body is usually outlined and measured. Bodily fluids as well as any cuts, broken bones, bruises, and other physical wounds on a murder victim can be very telling as to how he or she was killed, therefore evidence such as this is carefully noted. The position of the victim's clothing may suggest information about the crime, such as whether the body was moved from one location to another. In such a case, and many others, it is crucial to determine the exact location of the crime.

Taking photos at a crime scene is part of a crime scene investigation.
Taking photos at a crime scene is part of a crime scene investigation.

Other pieces of evidence can include broken glass, fingerprints, weapons, and bullets. Personal belongings like phones, computers, and diaries can also be very helpful in determining what happened. Even if the perpetrator took great effort to hide his or her deeds, it is extremely hard to fully conceal all clues so that a crime scene investigation yields no results.

DNA analysis may be conducted to identify suspects of a crime.
DNA analysis may be conducted to identify suspects of a crime.

Preserving and collecting physical evidence is called the mechanical aspect of a CSI, and is fundamental to every investigation. The thinking aspect, on the other hand, involves trying to understand what the evidence means and how it might explain the crime. The detective is heavily involved in this process, though his or her work may stretch on for a long period of time.

Police typically secure the crime scene area to ensure there is no outside interference.
Police typically secure the crime scene area to ensure there is no outside interference.

The evidence gathered in a crime scene investigation is normally processed at a crime lab by forensic scientists. Although the two fields overlap, a CSI unit is not necessarily the same as a forensic unit. A medical examiner can be considered as part of the forensics team and will typically submit reports of the exact time and cause of death to the detective, to aid in his or her investigation.

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    • Crime scene investigation involves gathering evidence at the scene of the crime.
      By: corepics
      Crime scene investigation involves gathering evidence at the scene of the crime.
    • Evidence left behind at a crime scene, like latent fingerprints, can be collected and used to implicate a suspect.
      By: Kevin Chesson
      Evidence left behind at a crime scene, like latent fingerprints, can be collected and used to implicate a suspect.
    • Taking photos at a crime scene is part of a crime scene investigation.
      By: Luis Louro
      Taking photos at a crime scene is part of a crime scene investigation.
    • DNA analysis may be conducted to identify suspects of a crime.
      By: Vasiliy Koval
      DNA analysis may be conducted to identify suspects of a crime.
    • Police typically secure the crime scene area to ensure there is no outside interference.
      By: ia_64
      Police typically secure the crime scene area to ensure there is no outside interference.
    • Patrolmen may create a perimeter around a crime scene during an investigation.
      By: ia_64
      Patrolmen may create a perimeter around a crime scene during an investigation.