Research-Based Practices Can Help Forensic Scientists Do Their Best Work

If a murder suspect’s DNA is found at the scene of the crime, juries often think of that as strong evidence of guilt.

One reason for this is that our public discourse around DNA may make it seem like an all-or-nothing concept to people who make up juries. Think of daytime TV shows revealing someone’s paternity, DNA tests that uncover family heritage, or the simple whodunit plot on TV where DNA indicates guilt.

But when it comes to crimes, you can’t always make a direct leap between the presence or absence of DNA and someone’s guilt or innocence.

One reason for this problem is that as technology improves, we can measure smaller amounts of DNA, so forensic analysts are finding more of it. Some of the DNA they’re finding is not necessarily relevant to the investigation. 

For example, imagine that investigators are looking at the scene of a crime in which a window was broken and the perpetrator, cut by the broken glass, bled. In the past, you would have needed about a dime-size amount of blood to get the suspect’s DNA from that blood sample. Now, you can get DNA from much smaller samples. Someone could have opened the window days before the crime or never touched it at all (because DNA travels through the air just like germs do), and a small amount of that person’s DNA might still be found. So having more DNA evidence means law enforcement and prosecutors need to answer questions beyond who the DNA belongs to. They need to answer questions related to how and when the DNA could have gotten there.

This presents interesting challenges to the forensic science community.

The Human Brain and Forensic Science Work

Another complicating factor in DNA analysis is the human element.  

Collecting, processing and analyzing DNA is a challenging job. Many factors can affect how useful DNA evidence is, including seemingly mundane issues such as the lighting in the room that the forensic scientist is working in or the temperature of the workspace.

Human factors engineering is simply designing an environment or process that works with, not against, the human brain. That may seem obvious, but unfortunately many things are designed without fully taking humans into account.

I led a recent NIST effort to address human factors in forensic science, with the goal of improving the field. We’ve produced several reports in this area, and the latest is Forensic DNA Interpretation and Human Factors: Improving Practice Through a Systems Approach. This work was supported by the Department of Justice’s National Institute of Justice.

For example, we humans have bad short-term memories. This is why it’s easy to forget your ATM card in the machine or leave your gas cap on the roof of the car. So ATM designers and car manufacturers have adapted to how our brains work. Most ATMs require you to take your card before you can take the cash. Many cars either have no gas caps or have them attached, so you can’t drive off with the cap on the roof.

Although forensic scientists who examine evidence are highly skilled and trained, they are subject to the same cognitive shortcomings that all people have — like the examples I listed above.

Helping Forensic Scientists Succeed

Our working group included law enforcement officers, prosecutors, defense attorneys and scientists from various disciplines, including psychologists. We thoroughly reviewed extensive research on what makes forensic scientists more and less effective in their jobs. Our team used that research to develop a list of recommendations that we hope all crime labs will follow.

We published these recommendations last year and have been working with the forensic science community to explain them and encourage adoption.

For example, one simple approach crime labs could adopt is making sure forensic scientists have a quiet workspace. Research shows that people concentrate better in a quiet environment, but many of these scientists are working in busy offices with ringing phones, people milling about and other distractions.

An additional recommendation we made is to create a safe environment for forensic scientists to identify and learn from their mistakes. Unfortunately, forensic scientists risk harm to their reputations for making honest errors. So rather than admitting and learning from these incidents, there’s an incentive not to discuss them. But this doesn’t help the profession improve. Creating a mechanism for forensic scientists to report their honest errors without fear of penalty can help the entire field.

For instance, if we can identify the cause of the problem, such as pressure to work faster, labs can take preventative measures. Labs might change their procedures, update their training practices or take similar steps to prevent the issue in the future.

Of course, this is different from intentional malfeasance, such as deliberately altering a sample to achieve a particular outcome, which should be addressed through appropriate discipline.

Another often-overlooked issue is that of trauma and stress. It’s not just law enforcement officers and first responders who are traumatized in the line of duty. Forensic analysts also suffer from vicarious trauma due to the types of cases they work on, such as child sexual assault cases. This is not only bad for the scientist personally, but it also may impact the quality of their work. In our report, we encourage crime labs to use approaches such as mandatory breaks, varying types of cases worked and providing access to psychologists to prevent burnout that keeps forensic scientists from doing their best.

These are just three nontechnical examples of dozens of suggestions we offered to crime labs to help them improve their work by using research-based approaches. This report provides a comprehensive discussion of all aspects of DNA analysis, from interpreting visual representations of DNA to reporting results to testifying in court.

We understand that adopting some of these recommendations — especially ones that require increased funding — may be difficult. We hope our systematic review of the latest science will help crime labs justify the resources they need to make these changes.

Finding Common Interests

The aspects of my job that involve consensus building are both challenging and rewarding. They require me to rely on the lessons learned from my unique mix of professional and personal life experiences.

In addition to having expertise in the human factors field and strong critical thinking skills, I have always had a natural ability to read people and assess group dynamics. I enjoy reading literature on building effective teams and learning how to decode body language. I’m also a mom of five kids, so I’m used to working with lots of different personalities!

Over the past 15 years, I’ve successfully led many working groups covering a wide range of topics and including people from all over the world. These experiences have honed my facilitation and negotiation skills, enabling me to navigate complex, sometimes contentious issues and achieve impactful outcomes.

This human factors work involved 25 experts in forensic science, statistics, legal and human factors fields. It was hard to get this group of people whose actual jobs are to argue with each other in court to reach a consensus on such a consequential issue. But being an eternal optimist, I entered into this project hopeful that I could create an environment where the working group members could see their shared interests, and we could build a set of recommendations that everyone could stand behind.

My Facilitation Approach

Organizational psychologist Roger Schwarz influenced how I manage groups. He’s identified core values of effective groups:

• Share valid information: Group members must share all relevant information they have in an understandable manner, allowing others to grasp the reasoning behind it.
• Make free and informed choices: Group decisions must be made on accurate information, free from external or internal pressures.
• Obtain internal commitment: Each participant must take personal responsibility for the decision and be willing to defend it.
• Demonstrate compassion: Group members must be compassionate with others and themselves.

After sharing these core values with the working group, we agreed on the ground rules that directed how we communicated, managed conflict and made decisions.

These are a few of the ingredients for my consensus-building success. Following my tried-and-true recipe allowed me to help this group create recommendations by keeping members focused on their shared interest in improving forensic DNA analysis in the future.

The Future of DNA Research

As we look ahead to the future in DNA, we need to start answering questions like the one I mentioned at the beginning of this post, with the broken window example. We need to expand the research beyond improving the technology’s sensitivity, so we don’t just collect more DNA without attempting to understand its context and relationship to the crime.

More research into DNA — how it moves, how long it lasts on surfaces, how investigators can best recover it and more — is needed to answer these important questions. NIST has a long history of contributing to this body of knowledge. Our labs have studied the effects of various environmental conditions and time after DNA lands on a surface. We’ve also done studies evaluating the scientific foundation of cases when evidence contains DNA from several people, known as DNA mixture analysis. I hope the forensic science field can continue to learn more about these questions so that we can make DNA evidence even more useful.

Crime labs rely on NIST for information on lots of other forensic science disciplines as well, including firearm examination, digital evidence, drug analysis and more. We also provide the physical reference standards and data that help forensic labs ensure accurate test results.

I truly believe in the importance of crime labs’ work. I know that NIST’s efforts empower them to do even better science, so justice can be administered impartially. Our work at NIST supports public safety, with a focus on improving quality of life.