Dangers of False Positives in Crime Investigations

False Positives in Crime Investigations

When building a case against a criminal suspect, authorities collect information and evidence from a variety of sources. It’s hard to imagine a person being wrongly convicted of a crime and serving years, even decades for something he or she didn’t do. But the reality is that this does happen – and maybe even more often than any of us imagine. Knowing how such a thing can happen opens up a lot of story lines for a crime writer.

When the Truth Lies 

False positives can come about in a variety of ways, but I’m going to focus on three of them: false positive DNA matches, unreliable eyewitness testimony, and the phenomenon of false confessions. To be fair, there are instances of false negatives in crime investigations as well, but I’m going to talk about the false positives because the risk of convicting an innocent person is at the center of the next Alex Stone Thriller following Stone Cold, which I plan to release in time for the holidays.

False-Positive DNA Matches

DNA evidence used to have a reputation for being infallible. Today, we know that this is wrong in both theory and practice. False positives can occur due to lab technician errors, mixing up or mislabeling samples, or misinterpretation of lab test results. The flaw in DNA testing reliability? Human error. And nothing stirs the pot of a potboiler better than human error.

Forensic scientists tainted DNA samples with their own DNA in eight of 23 cases in a Washington state forensic lab, according to a 2004 investigation. Advanced developments in DNA analysis technology have revealed almost 300 cases of false incrimination in the United States due to flawed forensic science, claims D. Kim Rossmo, Department of Criminal Justice, Texas State University, San Marcos, Texas.

In a recent case involving DNA cross contamination, suspect Lukis Anderson was wrongly charged with the murder of multi-millionaire Raveesh Kumra. Although investigators found his DNA on the murder victim, Anderson had been in the hospital at the time of the murder. Further investigation indicates that paramedics who transported Anderson to the medical center, also responded to the Kumra murder scene and likely contaminated the scene with Anderson’s DNA.

Although it’s now common knowledge that false-positive DNA matches can and do occur, the rate at which this happens is hard to estimate using existing data. The number of great crime fiction stories using this kind of a twist is easier to estimate – there’s a whole bunch of them!

Unreliable Eye-Witness Testimony

According to the Innocence Project website, “eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in nearly 75 percent of convictions overturned by DNA testing.” Dr. Elizabeth Loftus found that a person’s memory does not record events in a precise way, especially for traumatizing experiences. Instead, our brain stores bits and clips of what happened. Later, when we tell someone what happened, we’re actually reconstructing the experience, filling in gaps between the bits and pieces. We’re not aware that we’re adding or taking away from the story – it just happens. In fact, subsequent research strongly indicates that third parties can introduce false memories to witnesses.

In 2012, the television show, 48 Hours, aired a story about Ryan Ferguson who was serving a 40-year sentence for murder. Investigators found no physical evidence that tied Ferguson to the scene. The only evidence came from two eyewitnesses, one of who, Charles Erikson, is serving 25 years for the same murder. Later, both eyewitnesses recanted their testimony placing Ferguson at the scene. The judge denied Ferguson a new trial, but the report aired by 48 Hours suggests he might be innocent.

Exploring the unreliability of memory, the misperception of experience, and the differences in perception of the same events will provide crime writers with a rich array of twists and turns. You’ve heard the expression “you can’t make this up”. Well, we can and we do whether we’re witnesses or writers.

False Confessions

Why would an innocent person confess to a crime he or she didn’t commit, even without police coercion? Again, according to the Innocence Project, in about 25 percent of cases in which defendants are convicted and later exonerated by DNA evidence, the defendant incriminated herself by making false confessions or other incriminating statements.

I tackled this issue in Cold Truth, the third Lou Mason Thriller, when Mason defends a young woman who confesses to murdering her therapist. Talk about a steep hill for a defense attorney to climb!

Many factors contribute to a false confession: impaired mental state, fear or physical harm, intoxication, diminished mental capacity, ignorance of the law, threat of a harsher sentence if they do not confess. False confessions aren’t just a once-in-a-while occurrence. They’re actually a phenomenon – one that’s grabbing the attention of criminal justice authorities, defense lawyers and, hopefully, crime writers.

So, what if a person falsely confesses. He or she can just recant the confession and the system will reverse the conviction. Right? Wrong. It’s very difficult to reverse a conviction once the suspect has confessed. Frequently, the entire case has to be retried with attorneys poring over and presenting testimony and evidence used in the conviction.

False positives are a nightmare for an innocent person whose life and liberty are swept away because of human error or human frailty. Crime writers who incorporate these elements into their books help shine a light on the flaws in our criminal justice system and the need for vigilance in the protection of the individual. And readers of crime fiction get a kick out of seeing how we set things right.


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