Crime Scene Investigations
Once a crime is committed someone is sent to investigate it. It depends on the severity of the crime and the resources available in many cases as to who is sent. Some locations do not have the budget needed to have a dedicated team of highly trained investigators and may need the help of first responders and a detective to process the scene. Larger agencies may have investigators who photograph and collect the evidence.
The crime scene investigators will be looking for and collecting a variety of evidence depending on the crime itself. In a shooting, in addition to collecting biological evidence like blood, tissue, and hair, and collecting any prints at the scene, they will also be looking for firearm evidence. Whether a crime is inside or outside they may search for foot or shoe prints that might lead them to a suspect. Investigators will look for fibers, glass fragments, and other trace evidence that may seem out of place.
Securing the Scene
One of the first things investigators do once called to a scene is to make sure it is properly secured to protect any evidence from being destroyed or contaminated. Investigators need to establish the focal point of the scene and determine how big an area they need to secure. This is usually done by using tape that alerts people not to cross into the crime scene. Usually, when possible, an officer or officers will be posted to make sure people observe it and stay out of the area.
Investigators will look for any potential hazards that must be dealt with so that everyone working the scene stays safe. They will look for materials that could be dangerous such as explosives, weapons, or potential traps that could have been left behind.
Once they know everything is clear they will begin working.
Develop a Plan of Action
Investigators must try to determine what kind of crime was committed so that they can decide what kind of evidence may be present. If the crime is outside, they need to decide how to proceed to make sure all the evidence can be collected before weather or other issues could disturb or destroy it.
They will separate any witnesses, and someone will start interviewing them, if possible, to collect as much information about the crime as possible. This information helps investigators know how to proceed and what to look for specifically.
Scan the Scene
Investigators will make a preliminary survey of the scene to help them prioritize which evidence is most critical to collect first. Photos of the scene will be taken in careful detail before moving anything. This helps preserve the evidence so that they know exactly what evidence was where.
Often, they may have someone sketch the scene. Investigators will note if they smell anything like bleach which could indicate someone tried to clean up the scene. They will note if lights were on, or if doors are open or shut. They will put a cone by each piece of evidence and take a picture again with the marker so they can know precisely where each item was. Taking good notes is pertinent to the investigation.
The forensics team will use a variety of tools to capture the scene as completely as possible. They will do this process while following a strict protocol to ensure the evidence remains uncontaminated and admissible in court. Usually, a second survey is done to make sure they have not missed anything in the first walk-through.
Collect and Preserving the Evidence
Next, investigators will start the process of documenting and logging each piece of evidence into an inventory. It will be described in the log and must match the photo evidence already collected from the scene. This step is very important because it establishes the chain of custody of the evidence. From this point on a log of each step of what is done or moved of the evidence will be logged to keep the chain of custody documented accurately.
During this process, they will collect any biological samples from the scene. These include blood and tissue samples, body fluids, hair, and even bone fragments. These are crucial in getting an accurate DNA sample. DNA samples can help identify people who were at the scene recently or during the crime. Often a sample of the actual perpetrator will be collected aiding the prosecution in getting a guilty verdict.
Prints of fingertips, palms, and footprints will be gathered and saved to use for comparisons. This step is very important when trying to establish someone was at the scene that may have committed the crime.
Investigators will collect a variety of trace evidence. This can include fibers from material or other sources, vegetation, soil, fragments of glass, etc. Some of these will be hard to see without the aid of a magnifying tool.
If it is a shooting, they will look specifically for firearm evidence such as spent casing from bullets, holes in structures where a shot may have been fired and other items connected to firearms. They will look for other weapons that could have been used or left at the scene too.
Investigators look for illegal items like drugs. They will check for evidence to show if the victim let the suspect in or if there was a break-in. To do this they will look for tool marks and other evidence.
Analyzing and Presenting the Evidence
Investigators will look at each piece of evidence and try to figure out exactly what happened at the scene. They may even try to recreate the crime if needed to prove what happened. They will write a report explaining how the evidence fits together and later they will testify to everything they did and saw in court if needed. The notes, photos, and sketches along with each piece of evidence are essential in proving the evidence was properly processed so that it does not get thrown out of court.
Each of the steps listed above is crucial to ensure that the correct person is convicted of the crime. The steps and especially keeping the chain of custody of the evidence must be diligently kept secure so that justice prevails and only the correct suspect is found guilty. The evidence speaks the story that many victims cannot tell for themselves. Sometimes it may take years to bring to justice a crime, but the properly collected evidence can catch a criminal even decades later.