The Evidence Locker

Screenshot from Bones, created by Hart Hanson. Copyright 2005, 20th Century Fox Television. Used under fair use for educational purposes.

We’ve all seen shows like CSI and Bones, where the good guys always win with the help of forensics and the bad guy always gets caught. And we all probably realize that those shows aren’t realistic. But what, exactly, do they get wrong? Among other things, here are the top 7 things forensic shows get wrong.

1. DNA Matches Are Always Quick and Accurate
We all know the drill on a show: as soon as any molecule of DNA-containing material is found on a crime scene, the forensic scientists have the case essentially solved. DNA is the end-all-be-all of convicting a criminal. Not only that, results are quick and always definitive.
In real life, DNA is not always able to be retrieved, and even if it is, it can take weeks or even months to get a result. And when a result is received, if it’s a match, it isn’t a 100% guarantee that it’s going to be a slam-dunk case solver. And there’s a hundred things that could go wrong in the process, such as contamination or degradation of the sample.

2. A Single Drop of Blood Cracks the Case
While a single drop of blood may be a case solver for a TV detective, in real life, there’s much more nuance that goes into it. One singular drop of blood isn’t a case solver, especially not without context. Like with DNA, there’s a hundred things that could go wrong when analyzing a single drop of blood; human error, machine error, or other things. Forensic experts need much more than a drop of blood to be able to draw any sort of meaningful conclusions.

3. Forensic Investigators Solve the Case
On shows like CSI, it seems like the forensic scientists are the ones with the answers. They put together the pieces of the puzzle, and they’re never wrong. However, in actuality, it’s not the forensic examiner’s job to solve the case, and it’s actually discouraged. In order to avoid bias, which can taint test results, scientists are supposed to focus on the science. It’s up to the detectives to take the puzzle pieces and put them together to figure out who did what, and why.

4. Fingerprints are Always Reliable and Definitive
Fingerprints, as any latent print examiner will tell you, are far from an exact science. It takes lots of practice and experience to be able to identify patterns, and that’s when you’re working with perfect prints. Things like smudging, partial prints, and other factors that can interfere with even the most expert fingerprint examiner’s ability to interpret a friction ridge pattern.

5. The “CSI Effect”-Forensic Evidence Solves Everything?
The media has given the public the impression that forensics can solve any case. Not only that, people seem to think the process of forensic analysis is quick and tidy. This isn’t true, but it can have an interesting effect on juries as well as the general public; they can tend to give weight to forensic evidence that may be disproportionate. Forensic evidence is a useful piece of the puzzle when it comes to crimes, but it isn’t the only thing that leads to arrests or convictions.

6. Forensic Experts Always Know the Time of Death
Time of death is a tricky thing to ascertain. Sometimes, it can be narrowed down to a window of a few hours, but it’s rare that you can be any more specific than that. (Obviously, this doesn’t count scenarios like when a patient in a hospital dies.) This can mean it’s harder for investigators to figure out who could have been a person of interest, but since it’s never been possible to be perfectly precise with a time of death, this is something investigator are likely used to working around.

7. The Bad Guy Always Gets Caught
Unfortunately, real life isn’t always as neat and tidy as crime investigation shows are. Often, the bad guy gets away. This is more common in “petty” crimes like burglary, but does apply to homicides. However, as technology and forensics continue to evolve, hopefully rates of crimes being solved will go up.

In the end, while forensic shows like CSI and Bones offer exciting and fast-paced depictions of crime-solving, they often misrepresent the realities of forensic science. From the quick and definitive results of DNA testing to the assumption that a single piece of evidence can crack the case, these portrayals oversimplify the complexities of real-life investigations. In reality, forensic work is meticulous, takes time, and is far from foolproof. The roles of forensic experts and detectives are often more collaborative and nuanced than depicted, and the certainty with which cases are solved is not as guaranteed. Despite these misconceptions, the field of forensic science continues to play a critical role in criminal investigations, and as technology advances, we may see even more cases being solved with the help of careful, precise science.