The nature of criminal activity largely varies and so do the methods of processing the respective crime scene. Homicide scenes require extensive processing for any pieces of physical evidence that would prove helpful in solving the case. The way the Crime Scene Investigation of a homicide is done depends upon the law enforcement department and its resources. The resources allocated to a homicide case depend largely upon its severity and notoriety and the processing starts from the exterior of the scene.
Upon reaching the crime scene, the CSI Crime Scene Investigation team secures the crime scene after which the inspection is performed to make sure that the offender is still not present. Another purpose is to examine all the entry and exit points. The number and locations of these help the Crime Scene Investigator in forming multiple scenarios about the way it happened. During the exterior examination, any observations are jotted down and a plan regarding areas of the crime scene that need to be worked is formulated. Examples of such observations include broken windows, broken doors, damage to the door etc. This also involves the Crime Scene Photographer taking photos of the exterior from multiple angles.
Sketching with noting down exact measurements is another part of processing the exterior of the homicide scene. As soon as the processing of the exterior begins, gloves are worn to ensure that any physical evidence is not contaminated. Throughout the processing, the Crime Scene Technician and other members of CSI Crime Scene Investigation team wear these gloves. After the exterior has been processed, the team moves on to the interior where the homicide took place.
When moving around at the scene, care is taken so no one steps on an important piece of evidence. Upon entering the interior, the entry points are checked for any latent prints. While fingerprints may not always be left behind on a crime scene, there are some substances that can lead the investigators towards a latent print. These include organic and inorganic substances and environmental substances.
On a homicide scene, it is paramount to make sure that the body is not moved from its position before the medical examiner has done the initial examination. If there has been any movement in the body, the medical examiner needs to be notified. Upon examining the interior and exterior, a likely path is defined, which may have been taken by the offender. Other than collecting prints, the Crime Scene Investigator also traces what may have been the footsteps of the offender following that track may be useful in finding a piece of evidence. Other than looking at the floor, the investigation team also scans ceilings and walls. In violent crimes, the offender sometimes leaves a clue or message behind on the walls.
There are some homicide scenes at which every attempt to clear the blood marks, has been made. Criminals use materials like soap, water, Clorox other chemical under the impression that they can clean up their traces after them. In such a situation, the investigator singles out one more specific area as isolated spots for processing of possible evidence. Some of the signs that signal towards an area being suspicious include missing bed sheets and bedspreads or mattresses, missing furniture, floor that is spotlessly cleaned, a part of a carpet or flooring being changed recently, a piece of furniture or furnishing found out of place, a recent paint job on a particular part and formation of new stains for masking any blood stains.
The crime scene is also searched for impressions, which includes footprints or shoeprints. Those traces that are not otherwise visible are illuminated through a light that brings out the shoeprints. These prints are photographed and then lifted for comparison and analysis.
During search, the Crime Scene Technician checks the scene’s drawers and cupboards to know if anything was taken or left behind. The sketch preparer in the team draws the entire interior part of the crime scene with the perimeters and location of major object in the room. This sketch shows the windows and doors present. In making the sketch, every little detail is noted down including whether the windows and doors open inside or outside. The sketch preparer does this drawing. In bigger more resourceful departments, a crime scene reconstruction officer is present who reconstructs the entire crime scene with the help of software.
Once the medical examiner has examined the body initially at the crime scene, the examiner takes it to the lab where a detailed medical examination is conducted on the body. If there is excessive blood present at the homicide scene, there is a test that can conclusively tell if the blood is from an animal or human. This is called the Precipitin Test. A blood type can also be determined through using this test. A complete autopsy is done on the body and a report made with the findings.
These findings in turn help the entire CSI team to further investigate into the matter and come up with the possible methods as to how the murder took place. Every scene has variations and differences accordingly due to which extreme precautions need to be taken into account while solving them.