What is Crime Scene Investigation?

A crime scene refers to a place where a crime has occurred. The purpose of crime scene investigation (CSI) is to analyze the complete scene and catch the culprit based on the pieces of evidence collected from the place of crime. The people involved in this process are referred to as crime scene investigators.

What are the basics of CSI?

The process of crime scene investigation involves a juncture of three different concepts of logic, law, and forensic science. Investigating the crime scenes is a lengthy and tiresome process that requires the full attention of the investigating team. The whole scene is documented systematically, and then relevant physical evidence that can be utilized to solve the case and find the criminal is collected.

General steps involved in CSI

  • The CSI team reaches the crime scene when called by the policemen or detectives already present there.
  • After ensuring the safety of the scene, the investigating team takes a general walk through the scene. The investigators ask if any object has been moved before their arrival and formulate a rough theory based on their visual examination.
  • The team then takes a second walkthrough. It records the whole scene by making sketches, videos and taking pictures to ensure maximum scene documentation.
  • After completing the documentation step, the CSI officers carefully collect all possible evidence. They pack all the items in sterile bags for further analysis in the crime labs.
  • The crime lab team thoroughly examines all the collected evidence and provides a reliable report to the investigating officers.

The entire work of the investigating unit is divided into two parts. The fieldwork includes all the work done at the crime scene, and the lab work includes the forensics examination done in the labs by scientists.

Recognizing the extent of crime scene

Estimating the extent of the scene is the initial step in any investigation process. Once the investigating officers reach the crime area, they quickly analyze the type of crime and then estimate the scene's extent. Suppose a homicide case took place involving the death of only one individual. Then the extent of the crime scene would be the dead person's house and its immediate surroundings. If there are blood traces in the neighborhood, then the extent includes not only the house but the whole neighborhood.

Scene securing

After estimating the scene extent, the officers secure the crime scene. The police officers initially present at the scene usually do it. Before further investigation, the investigating officers arrange a search warrant for inspecting the secured area. The visual examination while estimating the scene's extent helps formulate a logistic approach for investigative purposes.

The estimated crime scene is secured and sealed for investigation using a warning sign labeled “crime scene investigation.” The image displays a crime scene in an open ground. Several objects in the scene are marked using numbers as pieces of evidence.
Securing the crime scene

Documentation of the crime scene

The documentation step is crucial and needs to be done precisely. It aims to record the entire scene in visuals so that the members of the forensics lab and the concerned prosecuting lawyer can accurately understand the scene. There are several ways that the investigators can use for documentation. These are:


Pictures are taken before the collection stage, and not a single thing is touched before taking the picture. The photographs clicked for documentation follow some guidelines and include three types of photography. The first is the overview image in which the widest view is captured; the second is the mid-range image in which the location of the evidence is captured. The last is the close-up image in which a clear view of only the evidence is captured. The pictures are then arranged in a photo log, and descriptions are added alongside them.


This method refers to creating a handwritten description of the whole scene. The process of noting the visual details is different from what is known to the common people and requires scientific observation. The investigator's notes are based on exact facts and are free from personal opinions or conclusions.


Sketches are beneficial as they document a wider view of the scene, along with better size descriptions. They can also describe the distances between different objects, such as a chair and a window.


Recording the entire scene via a walk-through video is of utmost importance in severe criminal cases. It helps estimate the time required to survey the entire scene or the time and number of steps required to move from one area to another. Videos are also useful for the future, as they may capture some details which investigators missed during prior documentation.

Detection of evidence

Once the documentation is complete, the crime scene investigation team starts searching the whole secured area for evidence. If the scene includes a dead body, it is first examined from all angles. The fingerprint of the dead is recorded, and the body temperature is also noted. Next, the entire area is examined in the following five ways:

Zone search

The entire area under survey is divided into separate zones, and each CSI team member is assigned one zone. The team members sometimes exchange their zones for cross-examination.

Parallel search

The CSI team members arrange in parallel lines for searching that line. All the members move from one side to another at the same speed.

Inward spiral search

The CSI team starts the analysis from the boundaries and moves towards the inside using the spiral movement method.

Grid search

It refers to examining the scene in the grid form, covering the area in two straight lines that intersect at 90 degrees.

Outward spiral search

In this method, the CSI team starts examining from the center of the scene and moves toward the outer boundaries in a spiral manner.

Collection of detected evidence

The main aim of the CSI team is to collect all the physical evidence in exact form without corrupting it. The team members wear gloves to prevent their own fingerprints from being imprinted on any collected item. All the collected items of evidence are grouped under different categories.

  • Residues of paint or gunshot, pieces of glass, any drug or chemical substance are grouped as trace evidence.
  • Marks of any tool or equipment, fingerprints, and impressions of footwear are referred to as impressions.
  • Knives, cases of cartridges, and guns are characterized as weapons.
  • Hairs and fibers.
  • Blood, vomit, salivary secretions, and semen are categorized as body fluids.
  • Handwritten notes (such as suicide notes), diaries, or answering machines are referred to as questionable documents.
The image displays a gun which is categorized as weapon evidence. It is present in the hand of a person who is either unconscious or dead. Next to him, there is a folded paper that maybe a suicide letter. The number 7 denotes the evidence number.
Gun is a crime weapon

Analysis of collected evidence

Forensic labs are where all the collected pieces of evidence are taken for scientific analysis. The reports of the tests are further forwarded to the investigating officers (CSI officers or police officers). The lab of the Forensic Bureau of Investigation (FBI) is the largest. It helps police officers and the members of CSI in their work.

The image displays a scene inside a forensic lab. All the fingerprints (a type of impression evidence) collected from the crime scene are examined by a forensic scientist with tools such as a brush.
Examination of fingerprint or impression evidence in a forensic lab

Common Mistakes

The crime scene investigation or the CSI is mostly misinterpreted as a field only related to criminology. In actuality, this involves science and logic along with criminology. Another misconception is that people may seldom treat forensic science as a separate field, but it is an application of science that is applicable only under legal interests (like crime scene investigation).

Context and Applications

This topic is significant for the professional exams of the following courses:

  • Bachelors of Science in Forensic Science
  • Masters of Science in Forensic Science
  • Masters of Science in Forensic Science and Criminology
  • Post Graduation Diploma in Forensic Science
  • Masters of Science in Criminology and Criminal Justice
  • Criminology
  • Forensic Study
  • Forensic Pathology
  • Forensic Chemistry

Practice Problems

Q1: What does CSI stand for?

(a) Crime Science Investigation

(b) Crime Scene Investigation

(c) Crime Scene Interpretation

(d) Criminal Science Institution

Correct option: (b)

Q2: In which of the following years was fingerprinting included in CSI?

(a) 1982

(b) 1877

(c) 1892

(d) 1902

Correct option: (c)

Q3: What is/are the importance of crime scene investigation?

(a) Evaluation of the type of crime

(b) Determination of the victim

(c) Detection of the culprit

(d) All of the above

Correct option: (d)

Q4: Which among the following can be categorized as "trace evidence?"

(a) Drug

(b) Hair

(c) Blood

(d) Saliva

Correct option: (a)

Q5: How many types of photography are done while documenting a crime scene?

(a) 2

(b) 1

(c) 5

(d) 3

Correct option: (d)

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