CSI Effect: forensic science between reality and fiction

Starting from 2000, the first season of CSI: Crime Scene Investigation debuted on TV and soon became one of the most popular “procedural” (i.e. describing the police/investigation procedures) series in the world. Similar series, including its spin-offs (CSI:Miami and CSI:NY) but also the various NCIS, Bones, and so on, have followed in its footsteps almost always repeating the same success.

They have allowed to bring the public closer to a previously little known aspect of the investigation of crimes, even if within written fiction it had already begun to carve out an important position (for instance the novels in the series of Dr Kay Scarpetta written by Patricia Cornwell, although the perspective was slightly different), namely that of the meticulous forensics work based on physical evidence and analysis, as opposed to the classic investigation made mostly of intuition.

The success of these series has, however, given rise to a phenomenon that has still negative consequences in the field of the real forensic science, or rather of its application in the legal field. This phenomenon is called “CSI Effect”.
It is due to the fact that what these series show is mostly fiction, even if there is some reality. The viewer (or the reader in the case of the novels), who isn’t an expert in the field, is often unable to distinguish fiction from reality and that generates expectations regarding the work of real forensic investigators, in relation to actual crimes, that are anything but realistic.

In the various CSI series and the like, for example, we see that all cases are solved thanks to the discovery of physical evidence that is irrefutable to link a suspect to the crime scene and then identify them as culprit.
Beside the fact that in reality the physical proofs that can be used are often very few and difficult to interpret, it is rarely highlighted that just a few of them are to be considered really relevant from a legal point of view. This category includes those that can be 100% (or almost) traced back to a single person. In other words, the only irrefutable physical evidence is a DNA match (which has an error rate practically equal to zero, unless you have to do with identical twins) and the dear old fingerprints. But even the latter have led to sensational errors, since the identification may present a not entirely negligible percentage of uncertainty.
Then you must consider that finding identifiable fingerprints is not nearly as common as it seems, while in almost all cases there isn’t the slightest trace of DNA.

All other physical evidence often proves absolutely nothing. When in the TV series we see criminologists get to a suspect by a small fibre, with the support of a mysterious (and even a little science fiction-like) database, and how this leads to their arrest and presumably to their conviction, well, in those cases fiction prevails.
This physical evidence in reality can be traced to a certain person with very low likelihood, because there are a number of factors why for example the fibre I mentioned before can come from many different objects and especially can be transmitted entirely by accident, through a chain of individuals, to the crime scene.

In a nutshell, in the real world it may easily happen that, in a case where there is a lot of non-relevant physical evidence (so no fingerprints and no DNA), this is by no means sufficient to convict someone. On the contrary, it may happen that there is a sentence based on a whole series of proofs that do not include any physical evidence.

Yet people watching these TV series has the false perception that this cannot, and indeed should, never happen.
This false perception, which is actually called “CSI Effect”, is the source of so many conflicting opinions from the media and the public about famous crimes, but also poses a big risk in situations where it arises in those who have the task of judging in the context of these crimes and are at the same time common people. I’m talking about jurors.

Jurors are people who do not always have the scientific background to really understand forensic science or the probability related to it, and this fact has led in some cases to judicial errors. In fact, it has happened that innocents were convicted because jurors had given too much importance to physical evidence with a low relevance, just as the classical fibre on the body of the victim who had vaguely to do with the suspect. In others the opposite happened: a culprit was acquitted because there was no physical evidence that gave the “certainty” of their involvement, although there were a thousand other facts or clues that gave rise to very few doubts (like motive, opportunity, and even eyewitnesses).

I heard for the first time of the “CSI Effect”, which is being studied since 2006, during an online course in criminology from the University of Leicester that I attended at the beginning of 2014, and I realised that I’m not free from it either.
I am a huge fan of these TV series (and also of Cornwell’s novels) and, even if I am fully aware that at least 60% of what I see (or read) is totally unreal (can you recall the typical DNA identification made in five minutes?), I was often pushed to think that the work of the forensic squad was really central, indeed indispensable in solving a crime (especially in murders).

This thought is so rooted in ordinary people who love mysteries and thrillers that they expect to see it in movies, TV series, and novels.
And we, thriller authors, end up giving them what they want, because what we write is not and should not be reality, but is fiction. You must not forget that.
Some of us try to be as realistic as possible and others, instead, move considerably away from what happens in the real world, but virtually all the authors of these genres bend reality to the needs of the story, so that the latter works and, in the meantime, the suspension of disbelief is maintained, which often has nothing to do with reality but only with its perception. Because, let’s face it, reality rarely fits the times and ways of narrating stories, or otherwise it can sometimes become boring for the reader who has specific expectations within a genre. Even when we write true stories, we end up novelising them so that they work.

I admit I did too with “The Mentor”, indeed I did it in a very strong way.
In the end, the only reality in it is London and its streets (some details of which are completely accurate, because I visited almost all of those streets in person) and some very general information about the organisation of the police (like the separation between the Metropolitan Police and the City of London Police). Concerning the rest, I took full licence.
In addition to assume that the employees of the forensic department at Scotland Yard are policemen (in the UK there is often a significant separation between the police, the investigators who work on the crime scenes, and the technicians who analyse the findings) and show a continuous and direct cooperation between them and a Murder Investigation Team, or making them use guns with too much ease - all essential devices to tell the story the way I wanted to (in this regard I wrote a note at the beginning of the book ) -, in my novel you can find clear traces of the “CSI Effect”.
On one occasion, for example, the main character, Detective Eric Shaw, manages to nail the culprit with anything but crystal clear physical evidence. In another, on the contrary, a myriad of clues together with the absence of a solid alibi does not seem sufficient to hold a suspect in custody even for a minute longer, because there is no physical evidence.
All this was done in order to bring the story in a certain direction that in the real world would never have occurred. But, remember, we’re always talking about fiction , so not only I could, indeed I had to do that. The important thing is to be consistent when you do it.

Here I enjoyed making both situations quite plausible, with explanations that are in line with the suspension of disbelief, so that, although these are a bit of a stretch, so far no one has perceived them as such (at least nobody told me they had), partly because of the way I presented them, but mainly because any reader of thrillers and mysteries is a victim of the “CSI Effect”, too.
And, although they are aware of it, after all, they like to think that justice is made of white and black, of incontestable evidence without which you don’t go to jail, that it is more likely that the culprit is caught rather than an innocent pay for a crime they didn’t commit. All this is reassuring against a real world made of incomprehensible statistics, uncertainties about the guilt, miscarriages of justice, approximate investigations and more, that we don’t like and that certainly don’t entertain us as, instead, fiction does. “Crime fiction” in all its facets is and should be entertainment. Let’s leave reality to documentaries and non-fiction.