HOW CRIME SCENE
INVESTIGATION WORKS
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How does crime scene investigation work?

With the explosion of the hit show CSI: Crime Scene Investigation, which exploded onto the entertainment scene 9 years ago, the public became extremely interested in things such as processing crime scenes, following trails of evidence, questioning suspects, and eventually putting criminals behind bars. The original show was so popular that other series were soon to follow, first with CSI: Miami and then CSI: New York. Who knows in which city there will be a new CSI team cropping up?

While these shows are very popular, are they accurate to what actually happens in the labs of real CSIs? Do the investigators really follow all of the steps of the criminal arrest or do they usually simply pick up the evidence and process it? And what exactly, does all of that entail? Here we’ll take a look at what happens in real CSI labs, how evidence is processed, and the different forensics that are used to find out just how crime scene investigation works.

What is CSI?

Crime scene investigation involves the combination of the exact right amount of science, knowledge, law, and a very, very steady hand. The job of a crime scene investigator is not a typical one, not even on a day-to-day basis. Crime scenes are always different and while they may know how to lift fingerprints, it may take years of experience before they master lifting them without disturbing any of the delicate evidence that surrounds them. This is because with every crime, every setting, every victim, and every suspect, investigators are facing new situations and must be able to adapt to and assess these new situations very quickly. They do this with the right personality for the job and some basic knowledge that can be applied to every crime scene.

Crime scene investigators are not usually the first ones at the scene of the crime but they are one of the first to arrive and it’s important that nothing is touched or disturbed before they arrive. This is so the investigator can get a good idea of the feel of the scene and obtain an initial understanding of what happened. The CSI will usually get a call from the police department or directly from the officer that was the first to arrive at the scene and at that time, the CSI investigator will head to the scene immediately.

Once the CSI arrives at the crime scene, they will first do an initial walk-through to make sure that the scene is safe and that all perpetrators have already left the area. This initial walk-through also allows the CSI to take note of the initial conditions and recognize anything that might be potential evidence. Nothing is touched at this point. Once the initial walk-through has been completed, the CSI will perform another walk-through, this time with the intent being more on finding evidence and understanding the scene rather than making sure it’s secure. Videotape is sometimes used to make sure that everything is documented exactly, photographs are always taken, and sketches are sometimes drawn. Still, nothing is touched.

Once the walk-throughs are completed, the CSI will then start to look at everything and will begin to collect anything that could be potential evidence. The evidence could include something as small as fine pieces of hair or could be as large as a car. Whatever the evidence is, it’s photographed, documented (what it is, where it was found, etc.), and will be bagged if possible to be sent to the crime lab. All of the evidence is gathered extremely carefully and great care must be taken not to disturb the evidence or any potential evidence around it. All of the bagging and documentation is done to ensure that the evidence remains in its original condition and is perfectly preserved. At this point the evidence will be sent to the crime lab. The CSI investigator might take it there themselves to process it or they will send it to the forensic scientists at the lab. Once the evidence has been processed and the results from testing are in, they will be given to the detective or officer working on the case.

CSI involves two different components of analyzing evidence. The first is field work and this is what happens when the investigators do their walk-throughs and document their initial observations at the scene. Field work also consists of the physical gathering of any evidence that is found at the scene. The second division of CSI involves lab work and this is when the evidence is analyzed at the crime lab once it has been delivered by the investigator that was at the scene. What happens in the crime lab is called forensic science and while some CSIs are scientists that specialize in this field, some are not. Those that work in the crime lab must be forensic scientists in order to properly process the evidence. However, the CSIs that are in the field must also have some knowledge of forensic science even if they’re not forensic scientists themselves, so that they are able to determine which evidence is important to return to the lab.

Scene Recognition

All crime scene investigations begin with scene recognition and this is when the CSIs first arrive at the scene. The initial officer or detective that arrived on the scene will have already blocked off a crime scene area but this is usually only in the areas where the obvious, or biggest part of the crime, has occurred. Once the CSIs arrive, they will generally block off a larger area and this area is usually one that is larger than necessary. This is done so that when the investigators are trying to determine what happened, they won’t have to worry that evidence has already been destroyed because people have walked through it. It’s easier to make a crime scene smaller than it is to make it bigger for this exact reason.

The investigators will also usually block off an area where they can rest and talk about the case without having to worry about interference from the press or onlookers. This part is one of the most important because all of the evidence must be properly preserved and sometimes the CSI has relatively little time to do so because of things such as weather conditions. After the crime scene has been marked and blocked off, the CSI will usually call the district attorney’s office to obtain a search warrant. This is done so that any evidence that is collected can be admitted into court. Otherwise, it is useless.

Once the search warrant has been obtained, the CSI will then walk through the crime scene again taking special note of things that will change as time passes. This could be something such as a very strong odour that will most likely decrease with time or maggots could be infesting rotting material and the infestation will get worse as time goes on. At this time the CSI will call in specialists that will be able to further help them determine what has happened. Blood spatter on a wall can be rubbed on a swab for collection but taking the entire wall to the crime lab is a bit more difficult. The specialists the CSI will call in will be able to offer greater insight into this type of evidence and how it fits into the case. The CSI will also at this time talk to officers and detectives that are working the case. Not only might they be able to offer even more insight but these are the people that usually talk to witnesses and people related to the case and they can pass this information along to the CSI. The CSIs themselves don’t usually speak to the witnesses themselves because they are not trained in interviewing witnesses and could unknowingly mislead them or misdirect them.

Once the CSI has spoken to everybody and done their walk-through they will then start to formulate a way they will collect the evidence. This is another important step because in order not to overlook details or crush evidence in the process, a plan must be fully devised and because each crime scene is different, each plan of attack must be different too. After the CSI has formulated their plan, they will then begin to document the evidence and the crime scene in such a way that it can be fully explained and understood by someone who was never there.

Scene Documentation

Documenting the entire crime scene is important because the CSI does not want to miss any details or information that could later prove to be very important and possibly, the keystone to the entire crime. When documenting the scene, there could be one CSI or a team that consists of dozens of CSIs but in either case, there are certain jobs that must be done. These include taking notes, taking photographs, drawing sketches, taking notes, and taking video of the crime scene.

Note-taking is very important at a crime scene as this is when the CSI can use words to describe what the crime scene looks like, what it smells like, and help fill in details that cameras might leave behind. It’s very important that CSIs don’t take notes with any sorts of opinions or assumptions in mind. Even if something looks like blood, the CSI must describe it such as ‘a reddish-brown fluid spreading from the victim’s body.’ This will allow for others to make their own objective guess at a later time.

Photographs are another major part of scene documentation. Before anything is touched or moved, there must be a picture taken of it. This is so that later when the CSI is analyzing the crime scene, they will be able to see exactly what it looked like. The CSI will take three different kinds of pictures: overviews, mid-views, and close-ups. Overviews will be taken of all rooms pertaining to a crime scene, meaning that if the crime scene is a bedroom in a house all the rooms in the house will be photographed. When the rooms are photographed a picture will be taken from each corner. The outside of the building will also be photographed and each entrance and exit will also be photographed. Often the onlookers that have gathered will also be photographed so that investigators can later identify witnesses or possible suspects. Mid-view photos will show evidence in context so not only the piece of evidence will be shown but also what was lying near it and around it. Close-ups are taken of individual pieces of evidence so that blood spatters may be shown and things like serial numbers can be documented. Photographs are then documented into the photo log along with information such as the location of the object, the description, and the time and date to name just a few.

Sketches are often used at crime scenes as well in addition to photographs because they can cover such a greater area than photographs. Where a photograph will only be able to show one room at a time, sketches can depict an entire home’s layout and how certain pieces of evidence relate to each other. Video is also used at crime scenes, not only to catch pieces of evidence and give investigators a better understanding of the scene, but also so that it can be analyzed how long it takes to get from room to room and how many turns it takes to get from one room to another.

Finding Evidence

Of course the object of every CSI is to find, collect, and preserve as much evidence as possible to enable them to piece together what happened and who is to blame. The types of evidence that CSIs are looking for are: trace evidence such as shattered glass, gunshot residue, bodily fluids, hairs and fibers, documents such as phone handsets featuring Caller ID or suicide notes. When there has been a homicide and a body is a piece of evidence, the CSI will at least examine all sides of the body and record initial observations. Further investigation on the body may be done at the scene by the CSI or they may wait until the body is in the morgue and perform their examination there. They will look for marks, bruises, stains, and other noticeable harm done to the body as well as observe things such as insect activity to determine time of death. This estimation however is often inadmissible in court due to the inaccuracy that could be caused by things such as changing conditions. The CSI will also take fingerprints of the body and it will then be wrapped in cloth and taken to the morgue where further investigation can be done.

When a CSI is determining their plan of attack for the scene, one of the things they consider is the path their search pattern will take. This is more than simply walking from the garage door to the bush; it involves following a specific path in relation to the crime scene and there are generally 5 different paths that a CSI will take. These are: the inward spiral search; the outward spiral search; the parallel search; the grid search; and the zone search.

The inward spiral search is just as it sounds: the CSI or team of CSIs will start on the outside of the crime scene and work their way in, working in a spiral direction. This is the most common type of search pattern that’s used when there is only one CSI working a case. The outward spiral search is the exact opposite with the CSIs moving away from the center of the scene and is most often used when the crime scene involves a dead body. The parallel search requires a number of CSIs because it involves all of the CSIs forming a line and walking at the same speed and same time from one end of the crime scene to the other. The grid search also uses this type of form however once the team is finished walking one way, they will form the same line and walk the opposite direction so if their path was marked, it would look like a grid. The zone search works by the crime scene being divided up into certain zones. One CSI is then assigned to search each zone and once the search is complete, they will then switch zones and search again.

Collecting evidence is a very slow task. This is because not only must the CSIs make sure that they collect all of the pertinent evidence but also that the entire crime scene is documented and recorded. Any piece of evidence that is gathered must also be bagged, tagged, and documented and this also takes a lot of time.

 

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