DNA & Other Forensic Evidence: Reliable or Fallible?

Is forensic evidence, like DNA, always reliable? The answer may surprise you. My guest today is a fellow research junkie. I'll let her explain why. Please welcome New York Times E-book Bestselling Author Debbi Mack to Murder Blog.

It's an honor to be here today as Sue's guest blogger. There are a few things I need to make clear from the outset. I am a lawyer, but no longer in practice. A practicing attorney needs many skills. Crime scene investigation is not necessarily one of them.

If I'd been an attorney who handled numerous criminal cases, I'd probably have more insight into police procedure than I do. But as you probably know, lawyers come with different fields of expertise. In my case, those fields included Social Security disability law, environmental law (I worked with the pesticides and toxics programs at EPA), plus zoning & land use law. I worked in each of these areas for a period of time before I decided to go into business for myself. That's when the real learning started—when I opened my own office.

As a general practitioner, I did what my peers called "door law", which was pretty much as it sounds—we handled whatever cases came through the door. Those could include a wide variety of legal matters, from wills to divorces to minor criminal cases. And not even once did I take on a client accused of murder.

But what all attorneys must do—and are, in fact, trained to do—is conduct careful research, read closely, and think like a lawyer. And since I write mysteries about a lawyer who investigates murders connected to her cases, I tend to research and read about the subject of criminal investigation a lot. Not to the point where my protagonist would be a CSI specialist, but at least to the point where she would know where to poke holes in a prosecutor's case.

In other words, a defense lawyer needs to know enough about police procedure to be able to attack the veracity or trustworthiness of the prosecutor’s evidence. Because in the United States, everyone really is (theoretically) innocent until proven guilty beyond a reasonable doubt. That's the highest standard of proof.

Now, setting aside everything I could say about how wrong it is to try a person in the media (or, these days, by social media)—which I could easily rant about at length—I’ll discuss why forensic and DNA evidence are not always conclusive proof of guilt.

Several examples of people wrongly convicted based on forensic evidence.

First, from July 2016 issue of National Geographic, here's an excerpt from "Beyond Reasonable Doubt":

"[O]ver the past decade or so, it's become apparent that many forensic methodologies offer far less certitude than TV dramas suggest. And when forensic evidence is oversold in court, innocent people go to jail, or worse.”

Kirk Odom’s case is one example. He was prosecuted and convicted of rape based on an FBI analyst’s testimony that Odom's hair was “microscopically indistinguishable” from a single hair found on the rape victim’s nightgown. Odom spent more than 22 years in prison and eight on parole as a sex offender before the public defender's office dug up new evidence proving his innocence.

Odom was lucky compared to Cameron Todd Willingham who CONTINUE READING...