Basic Stages for a Crime Scene Investigation — Possible Homicide
Don Penven
Approach the Scene
The crime scene investigator returns the microphone to its clip and begins the drive to the latest assignment. A crime scene investigation begins well before the CSI enters a structure, an open field or wooded area. Usually the radio dispatch message is brief and seldom reveals the full nature of the incident. Most often this is done to avoid drawing on-lookers and the media who may be monitoring the dispatch frequency. As the CSI turns onto the street in question, his first obligation is to "turn on" his powers of observation. He may make a mental note of what he sees, hears and smells-or better still-records them on a digital voice recorder. His first reaction to the scene must be, "Does anything look out of place? What odors may be noticeable and are there unusual sounds.
See also the instructional video "Processing the Crime Scene"
Secure and Protect the Scene
Hopefully the first responders haven't caused too much disruption to any potential physical evidence. Before even stepping inside the structure, ingress and egress to it must be controlled. Sentries at all possible entrances should be put in place. The CSI, after learning the basic facts-in this case it appears that a white male appears to have a single bullet wound the head and rigor has set in-- this from the first responders, so the CSI will establish the boundaries of the crime scene. Then… out comes the crime scene tape.
Initiate Preliminary Survey
Again… before entering the structure an exterior survey is needed. This may be nothing more that walking around the exterior of the structure to see if any obvious evidence is apparent. This would include open windows, damaged doors, ladders and the like. The question the CSI is asking is… how was entry made to the structure? Once indoors, the CSI will make a visual survey of the actual room in which the incident reported took place. This is a good time to also take overall photos of the scene. He will then survey adjoining rooms to determine if these spaces may have information relative to the incident. Most law enforcement agencies conduct such investigations of an unattended death (no physician present) as a possible homicide-until it is determined otherwise. Unlike some TV dramas, the CSI is on site for the purpose of finding, evaluating and collecting physical evidence. In most agencies, statements from witnesses and survivors are handled by the investigators/detectives.
Of course, during this entire survey period, the CSI is taking notes and/or recordings of his sensory observations.
Evaluate Physical Evidence Possibilities
The very nature of what appears to be obvious should trigger the thought-processes of the CSI. What happened here, when did it happen and what sort of evidence should be present? Questions that should be answered initially are:
- Did the shooting occur in this room
- Has the body been moved (by first responders or perpetrator(s)
- Has any object been moved (especially by first responders or family members
- Were additional shots besides the one in the victim's head. This means examining walls, ceiling, room objects, etc.
- Are shell casings apparent. If so-mark them with placards, evidence tents, etc. so they will be obvious in photos.
- Are traces of blood apparent in other areas of the room-indicating movement of the victim
- Is blood spatter apparent
- Are there signs of a struggle
- Are there visible footprints in the blood
Each crime scene may well generate other questions to be answered by the CSI. The above list is simply the most obvious questions.
Prepare a Narrative of the Scene
The CSI's notes can serve as a very critical part of the overall physical evidence available from the scene. The investigator must keep in mind that months or even years later this case may go to trial. Your notes must present the full story of what you saw and any impressions the evidence gave you. Avoid speculation as to what occurred unless you have physical evidence to back it up.
Capture the Scene Photographically
Be certain to have overall, medium range and close-up shots of any potential physical evidence. Be certain to include scales in the close-up shots.
Prepare the Crime Scene Sketch
Many CSIs will prepare the rough sketch at the scene and will complete a detailed sketch back at headquarters. The rough sketch should contain no more or no less than the final, detailed sketch. It is always recommended that an assistant help out when taking measurements, and it's a good idea is to have this individual verify each measurement to avoid questions later.
Conduct a Detailed Search
Go over every square inch of the scene in an attempt to locate even the smallest particle of evidence. (This brings to mind a recent case wherein a woman was brutally beaten to death in her bedroom. Several days after the crime scene was released to the family, the victim's sister found a tooth from the victim on the bedroom carpet). Many crime scenes warrant the use of an evidence vacuum in the scene to collect any potential microparticle evidence such as hair and fibers. This step should be performed prior to any close in inspection of the victim.
Record and Collect Physical Evidence
As potential evidence is located it should be recorded on the crime scene sketch as well as in photographs. If your agency offers the luxury of having a videographer on hand, video often tells a compelling story to a jury.
Crime scene evidence is useless unless it is properly marked and packaged and a Chain of Evidence is begun from the time it is picked up. Use the proper type of containers for all evidence collected. Never package objects wet with blood or other physiological fluids in plastic bags, as this will accelerate decomposition. Label and identify all evidence collected, including the notes taken by the investigator.
Of course, the digital age we live in takes note of electronic devices like computers and cellphones. This type of evidence requires special handling and only experts trained in working with digital items should be permitted to handle and collect these items.
Conduct a Final Survey
Be certain that every package containing physical evidence is collected—leave nothing behind. Make a final walk-through to be certain that all potential evidence is bagged and tagged.
Release the Crime Scene
While it is normal for others having an interest in the property to want to regain access, the CSI should not be rushed, coaxed or bullied into releasing the scene until the job is done.
About the Author
Don Penven has more than 35 years direct and indirect experience in law enforcement. He currently serves as a technical support representative and technical writer for Sirchie Finger Print Labs.
Article submitted by the Author
Article posted: November 1, 2012