The Last Word

Forensics in popular culture hadn’t hit its peak and Trejos had little idea of what she was getting into.

They put her to work with her first piece of evidence: a T-shirt smothered in dried blood and “white stuff.” Trejos thought, “Why would this shirt have so many rice grains?” It was not rice. It was maggots.

This ghastly display did not push Trejos away from the field. Rather, it sparked her fascination in applying chemistry and science to answer questions about crime.

Now, as an associate professor of forensic science at WVU, Trejos is igniting that same curiosity in the next generation of scientists.

Q: What's the best thing about being a forensic scientist?

The ability to use your scientific knowledge and skills to put pieces together that can lead to a fair and prompt administration of justice. Every time that I open a case, there is communication between the evidence and the scientist. We let the evidence become the “mute witness” that can help decipher clues about what, when or how things may have evolved in a criminal event.

Q: You and some of your students developed a method to standardize protocol for examining duct tape and comparing pieces of trace evidence. Can you discuss the process of analyzing duct tape from a crime scene?

Tape can be utilized in many violent crimes, to gag a victim, to build an improvised explosive device, to wrap up kilos of cocaine. In that process, tape can retain multiple types of evidence, such as DNA, fingerprints or other minute traces of fibers, soil, glass and paint, to mention some. Therefore, a single piece of tape can tell a lot of details about the events and the environment to which that tape has been exposed.

Even in the absence of DNA and fingerprints, tape can hold valuable information. For instance, forensic scientists can evaluate the physical and chemical properties of a (piece of) tape and provide lead information about potential manufacturers and suppliers by using databases. Also, when a tape is separated from the roll by cutting or hand tearing, the fractured edges can retain distinctive features that demonstrate the two pieces were once joined. This is known as a “physical fit” or fracture match and can hold high probative value.

Imagine a kidnapping case, where the victim has been bound with duct tape, thrown into a car trunk and transported to a remote location. Not only could tape edges be linked to a tape roll in the possession of a suspect, for example by a physical fit, but also the minute microfibers from the trunk carpet and from the clothing of the suspect can be trapped and preserved on the adhesive side of the tape. Fibers from the friction of the victim’s body can also be left behind on the trunk. Those fibers help describe the succession of the criminal activities and places where they took place, providing stronger understanding of the linkage between suspect, crime scene and victim.

The crime scene investigator and forensic examiners must decide the priority of analysis on a case-to-case basis. DNA and fingerprints can help identify who has handled a piece of tape. Other types of trace evidence in the tape can explain how that evidence got there, and how and when events happened.

Q: Your husband, Luis Arroyo, is also a faculty member in the forensics department. How did you two meet? Out of love for forensic science?

I was doing my undergraduate research thesis at the University of Costa Rica where we met, became close friends and fell in love. He is a humorous and rogue character, that complements my shy personality. He always makes me laugh and helps me see the positive aspects, even in difficult times.

After getting married, we each had our own exciting jobs before he convinced me to go back to graduate school with him. While earning our PhDs, we were blessed with two kids, Montse and Tony, and our careers in forensic science have since been one of our driving passions.

Until joining WVU, we had our own research interests, but increasing attention to gun violence in the U.S. brought us together for a project that has developed innovative analytical methods to do fast screening of organic and inorganic gunshot residue, which are residues left behind after the discharge of a firearm. The students in our research groups have adapted well to this joint effort and have sparked a very productive research area that has strengthened the international prominence of WVU’s forensic program. We joke that we are “partners in combating crime.”

Q: What is the biggest misconception about forensic science?

I believe most misconceptions come from TV shows. A good portion of students interested in forensic science come to our program not realizing that attending a crime scene or working in a forensic laboratory requires a strong science curriculum. To become a forensic scientist, you first need to become a scientist, and then apply those scientific concepts to forensics.

Also, some people participating as jurors or lawyers may have unrealistic expectations about turnaround times or error rates in forensic science. A common misconception is that “forensic scientists can always reach definitive conclusions.” The reality is that the results of an examination depend on many factors, including the quality of the evidence recovered. In certain cases, the evidence is just not there, or can’t be detected.

Another common misconception is “all cases can be solved with DNA.” A significant proportion of law enforcement agencies continue to focus mostly on DNA and misunderstand the potential benefits of other types of evidence. The reality is that DNA could be a great probative piece of evidence, but it can’t always provide a relevant answer. For example, recent articles have reported that in some agencies, as much as 50% of DNA examinations do not result in a match with a person in a DNA database, and much lower success rates are associated with finding the person of interest.

Thus, it’s important to acknowledge that the use of multiple pieces of evidence, and rarely a single piece of evidence, is what ultimately can establish a more definitive answer. Ultimately, we can’t put a price tag on the delivery of justice or see it as a one-size-fits-all business.

Q: How did you end up at WVU?

I didn’t believe in destiny until multiple life events led me to believe all things happen for a reason and at the right time. Coming to WVU was one of them. My husband and I are both forensic chemists with different areas of expertise. He specializes in drug, environmental and forensic toxicology; my specialty is in trace evidence. When WVU built the opportunity to develop a Ph.D. program in forensic science, two areas of interest for the program were trace evidence and forensic toxicology. We came to the WVU interview with no expectations, and after meeting with the chair at the time, Dr. Lang, and the faculty and students, we were impressed with WVU, the forensic program, the WVU pride and the quality of the education provided here. Soon, we were caught on the wild and wonderful West Virginia, WVU, Morgantown and their people. It has been one of the most rewarding experiences in my career.

Q: What is there left for you to accomplish?

I feel I'm just scratching the surface. There is so much I would love to learn and contribute to the field. I would like to grow in many directions, one of which is improving my leadership skills to pass on my passion for forensics to newer generations. I want to become a leader for them just like there have been leaders for me who have inspired me.