The Future of Forensic Analysis: An Interview with Brooke Kammrath

As part of “The Future of Forensic Analysis” content series, Spectroscopy sat down with Brooke Kammrath of the University of New Haven to talk about the significance of spectroscopy in forensic analysis.

Brooke Kammrath of the University of New Haven forged a unique path to becoming an internationally recognized forensic science researcher.

As a chemistry student at Northwestern University in Chicago, Illinois, Kammrath initially planned on becoming a chemistry and physics teacher, which led to her to pursue a master’s degree in chemistry education from New York University (NYU) back in 2003.

However, after a few years of teaching, she opted for a career change and took steps to become a criminalist specializing in forensic chemistry. Kammrath received an MS in forensic science from John Jay College of Criminal Justice before pursuing a PhD in Criminal Justice at the CUNY Graduate Center.

After obtaining her PhD in 2012, Kammrath joined the faculty at the University of New Haven, pursuing research endeavors that included combining microscopy with spectroscopy, identifying and characterizing microscopic forensic samples, statistical analysis of trace, pattern, and impression evidence, developing portable instrumentation, and investigating the significance and impact of physical evidence. She has served as the president of the New York Microscopical Society (NYMS) and was on the Governing Boards of NYMS, the Society for Applied Spectroscopy (SAS), and is currently on the Eastern Analytical Symposium (EAS) board. Additionally, she is a certified criminalist by the American Board of Criminalistics (ABC).

Recently, she has collaborated with other researchers in the field on several published books, including Solving Problems with Microscopy: Real‐life Examples in Forensic, Life and Chemical Sciences, Blood Traces: Interpretation of Deposition and Distribution, Portable Spectroscopy and Spectrometry 1: Technologies and Instrumentation, and Portable Spectroscopy and Spectrometry 2: Applications.

Kammrath currently serves as a Professor in the Henry C. Lee College of Criminal Justice and Forensic Sciences at the University of New Haven, as well as the Executive Director of the Henry C. Lee Institute of Forensic Science.

As part of “The Future of Forensic Analysis” content series, the editors of Spectroscopy spoke to Kammrath about her career in forensic science and her ongoing research in this field. Our interview with Kammrath covers a breadth of topics, including her collaborations with some of the most well-known spectroscopists and how recent developments in spectroscopic instrumentation will impact forensic analysis moving forward. Our conversation reveals her unique path to becoming one of the leading forensic analysts of our time.

Dr. Brooke Kammrath of the University of New Haven. | Photo Credit: Brooke Kammrath

I would like to start this interview by offering our readers a glimpse into your background. How did you become interested in forensic science, and how has your academic career shaped your research in this field?

I first learned about forensic science when I was a college chemistry major at Northwestern University and CSI premiered on television. I thought it featured the most outstanding application of natural sciences (chemistry, physics, and biology). But I continued on the path I had planned for myself for the next several years, as a high school chemistry and physics teacher, even getting a master’s in chemistry education from New York University (NYU). After a few years of wishing I could have a different career, I took the steps needed to become a forensic scientist. Forensic science is more than just applying chemistry to a crime scene problem, because there are nuances and questions in forensic science that are unique to this discipline that require specialized knowledge. I attended John Jay College of Criminal Justice in NYC for my master’s in forensic science, which is where I was fortunate to learn from extraordinary professors about all aspects of forensic science. It was at John Jay College that I was inspired to pursue a career in academia, which would allow me to teach and mentor students, do meaningful research with brilliant collaborators, and consult on interesting and complex forensic cases. To achieve this, I continued at the CUNY Graduate Center for my Ph.D. in Criminal Justice with a concentration in Forensic Science.

I have been incredibly lucky to have some phenomenal mentors, most notably Professors John A. Reffner, Peter De Forest, Nicholas D.K. Petraco, and Nicholas Petraco, Sr., who have shaped all aspects of my research and approach to forensic science problem solving. Regarding my research, my academic journey has taught me to rely on the fundamentals of good science, to take chances because you never know where opportunities will be uncovered, to ask relevant questions (which is critical for meaningful forensic science research), to seek out diverse collaborations because alternative perspectives are always valuable, and to believe in the power of kindness.

You are also a certified criminalist by the American Board of Criminalistics (ABC). Can you talk about what the process was for certification, and how this has aided your research and career?

As an academic and private consulting criminalist, I recognized early in my career the importance of certification. For me, certification by the ABC is a credential that verifies my qualifications (skills, knowledge, experiences, and abilities) as a forensic professional. I find external validation particularly valuable in my role as an expert for the court and as a professor in an applied field, but I have not found it to aid my research. At the time of my initial certification in the mid-2000s, I obtained the General Knowledge certification from the ABC, which was like the current Comprehensive Criminalistics one, which covers a variety of forensic disciplines rather than one specific specialty. The initial process involved passing a notoriously challenging exam, but maintaining certification requires demonstrating continued competency yearly. This can include casework, teaching, publishing research, attending conferences or workshops, and more.

Over the past few years, you’ve published several books in this space, collaborating with other well-known spectroscopists, such as Richard Crocombe and John A. Reffner (1–4). How did you get involved in these projects?

Reffner is my mentor, having advised both my master’s and PhD theses in which the use of infrared (IR) microscopy was investigated for the identification of soil minerals and the forensic discrimination of glass fragments. He is an incredibly brilliant, thoughtful, generous, and accomplished man who has been a source of wisdom, teaching, and support for me since the day I met him in 2006, when I attended a New York Microscopical Society (NYMS) professional microscopy workshop he was teaching. In 2018, John and I were talking, and he expressed that he had always wanted to write a book. He asked if I would help him realize this last professional bucket list item, which was a true honor. When discussing possible topics, it became obvious that we didn’t want to write a typical “how-to” book that instructs people how to perform a specific microscopical technique; instead, we wanted to capture the more elusive “why-to” that can help people understand the powerful capabilities of microscopy and microspectroscopy for solving problems. I was able to take a semester sabbatical from my university work to spend every day brainstorming, writing, and doing microscopy and spectroscopy with John, which was one of the most incredible professional experiences of my career.

While a master’s student, I completed a summer internship at Smiths Detection under the supervision of Reffner and Pauline E. Leary. Leary is an incredible scientist, collaborator, and friend. For over 15 years, Leary and I have worked together on numerous research projects on a range of topics of forensic interest, from investigating the dispersive effects of barium fluoride cover slips on the quality of IR spectra for potentially hazardous samples in a sealed cell (5) to the field analysis of explosives and illicit and counterfeit drugs (6–8). Richard Crocombe and Leary teach an informative workshop on portable spectroscopy and spectrometry, which is still offered at select conferences. Crocombe recognized the need for a comprehensive resource on portable spectroscopy and spectrometry, and when the project expanded to a two-volume book with 45 chapters, I was invited to join as a co-editor. It was an incredible opportunity to work with Richard and Pauline on this project, and even more wonderful is that I am able to expose my students to their brilliance when they come to the University of New Haven for continued collaborations.

Your most recent publication, Solving Problems with Microscopy, presents examples and lessons regarding the value the microscope brings to problem solving by experienced scientists in various industries, including in criminal and civil forensic science (1). Can you provide our readers with a couple of highlights from the book that you found particularly interesting when working on it?

That is an incredibly difficult question because each case example included in the book is fascinating to me and highlights a different aspect of scientific problem-solving using microscopy, microspectroscopy, or both. As a forensic scientist, I am partial to murder investigations, which include the cases of the Green River Killer, the Buttonier Case, A Connecticut Murder Case, the Red Hooded Sweatshirt, the Atlanta Child Murders Investigation, the Hog Trail Murders, the Hoeplinger Murder (co-authored with Dr. Henry Lee), and the Preppy Murder (co-authored with Peter R. De Forest). A highlight, in my opinion, is the Green River Killer case, where the microscopical and Fourier-transform infrared (FT-IR) microspectroscopical analysis of vacuum sweepings from the victims’ and suspect’s clothing was shown to contain microscopic spray paint spheres. This work was completed by Skip Palenik and other scientists at Microtrace, who, with this work, elegantly demonstrated the value and potential of the interrogation of microscopic traces.

Additionally, two cases from scientists at the US FDA Forensic Chemistry Center, “A Mouse, a Soft Drink Can... and a Felony” by S. Frank Platek and Nicola Ranieri, and “Optical Microscopy Takes Center Stage: Melamine in Pet Food,” which is authored by Mark Witkowski and John Crowe, are fascinating, brilliant, and have the most elegant scientific problem-solving.

What are the key spectroscopic techniques you use in your forensic research (for example, IR, UV-vis, Raman, NMR)?

I have used a variety of spectroscopic techniques in my research because there isn’t just one instrument used to interrogate forensic traces. My research involving portable instruments uses a variety of spectroscopic techniques, including FT-IR, Raman, near-infrared (NIR), gas chromatography–mass spectrometry (GC–MS), high-pressure mass spectrometry (HPMS), and ion mobility spectrometry (IMS). My research into soil mineral identification has focused on IR and Raman microspectroscopy, specifically particle-correlated Raman spectroscopy and morphologically-directed Raman spectroscopy. I’ve also used laser-induced breakdown spectroscopy (LIBS), scanning electron microscope–energy dispersive X-ray spectroscopy (SEM-EDX), atomic absorption (AA), and X-ray fluorescence (XRF) for elemental analysis of a variety of traces, including gunshot residue (GSR) and copper metal.

How do you determine which spectroscopic method to use for a particular forensic analysis? Is there a specific spectroscopic technique that you’ve often used in your research?

The problem needing to be solved will direct the scientific investigation. For me, it’s about understanding the fundamental question (or questions) being asked, balancing that with the limitations and capabilities of the available tools and circumstances, then coming up with a logical plan. For example, if sample size is limited, non-destructive microspectroscopical methods (for example, FT-IR or UV-vis microspectrophotometry [MSP]) will be used and explored first (after macroscopic and microscopic examinations, both with proper documentation) prior to destructive methods like pyrolysis-GC–MS (Py-GC–MS). Forensic paint analysis is an excellent example which shows the integration of spectroscopic methods within a forensic analytical scheme and is brilliantly detailed by Scott Ryland and Ed Suzuki in their book chapter, “Analysis of Paint Evidence” (9).

When evaluating new spectroscopic tools, the question often asked is how they compare to existing methods, and if they provide added value to that which is already being done. Spectroscopic techniques must demonstrate that they are fit-for-purpose, and in the forensic landscape, that can be very difficult and take a long time.

How does one ensure the reliability and accuracy of spectroscopic data in forensic investigations?

There are well-known good laboratory practices and methods that are used in all scientific pursuits to ensure reliability and accuracy that must be completed in all forensic scientific investigations. These include, but are not limited to, adherence to the scientific method (and its iterative process of critically testing hypotheses), the maintenance of standards and controls, and transparent documentation of everything (from sample selection through analysis and including interpretation). Thorough testing of new methods needs to be done not only on mock evidence, but in real-world cases as well, which is why collaboration with practitioners is essential for impactful forensic research and development.

What recent advancements in spectroscopic techniques do you find most exciting or promising for forensic applications?

There are quite a few exciting new advancements in spectroscopy that I think may have meaningful applications for interrogating forensic traces. I’ll discuss three.

Of particular interest to me are methods that can correlate physical and optical properties analysis with chemical analysis, such as IR or Raman spectroscopy. These methods include FT-IR and Raman mapping as well as automated imaging paired with Raman spectroscopy methods, such as PCRS and MDRS.

Optical photothermal IR spectroscopy (O-PTIR) is an incredibly powerful technology that has great potential for discriminating material traces at a level not yet explored. I have been fortunate enough to work with this technology, albeit in a limited capacity, and I saw how O-PTIR can add value to molecular spectroscopic methods currently used in forensic laboratories, such as with the discrimination of automotive paint samples. O-PTIR is able to provide comprehensive non-destructive analysis of automotive paint layers without contact, including those previously too thin to analyze (< 10 µm). The spatial resolution afforded by O-PTIR, combined with the potential for pairing it with Raman and fluorescence spectroscopy, makes it, for me, a technology to watch.

Lastly, portable spectroscopic technologies have the exciting potential to bring powerful science to the scene. Some portable spectrometers are incredibly advanced with capabilities on par with their benchtop counterparts (for example, FT-IR spectrometers), whereas others are relatively new technologies that need additional research and real-world validations to understand their capabilities and limitations. Ultimately, Star Trek’s tricorder is still far from reality, and there is no single portable spectrometer able to analyze all samples. Thus, a “toolkit” approach is recommended, and research into the tools in this kit is much needed and very exciting.

In addition to the different portable spectrometer tools available, I find it exciting that there is a plethora of forensic traces that may be analyzed at the scene with portable spectrometers to provide investigative information. Suspected illicit drugs and explosives are the most researched and used items of forensic interest with regard to portable spectroscopy, but there is also great potential with regard to the analysis of paint, GSR, bullet impact or ricochet marks, body fluids, comingled remains, and much more.

How do you stay updated with the latest developments and research in the field of forensic spectroscopy?

In my opinion, there are three essential ways to stay abreast of the latest developments and research in the field of forensic spectroscopy: (1) conferences, (2) professional organizations, and (3) journals. Attendance at professional conferences, both chemistry-focused ones like EAS, SciX, and Pittcon, and forensic-centered ones, such as AAFS and NEAFS, is incredibly rewarding on numerous levels, including learning about the next new tools for forensic problem solving. Just as important for continual growth is membership in professional organizations, both chemistry-focused ones, like the Society for Applied Spectroscopy (SAS), the Coblentz Society, the New York Microscopial Society (NYMS), and forensic-centered ones, such as the American Academy of Forensic Sciences (AAFS), the Northeastern Association of Forensic Scientists (NEAFS), and the American Society of Trace Evidence Examiners (ASTEE). Finally, I also read and critically evaluate published research and reports from a variety of forensic, chemistry, and spectroscopy journals.

What advice would you give to someone looking to pursue a career in forensic science with a focus on spectroscopy?

The best advice I have is borrowed from Louis Pasteur: “Fortune favors the prepared mind,” so prepare yourself. Preparation is first done through education, and you will need quality chemistry (especially analytical chemistry) and forensic science courses to achieve this goal. An aspiring forensic scientist can also get fantastic opportunities through membership in professional organizations and by attending in-person conferences, both for forensic science (for example, AAFS, NEAFS, and CAC) and chemistry (for example, EAS, SciX, and Pittcon). These experiences will not only add to your resume, but they will also add to your knowledge, thus making you a more valuable forensic scientist.

References and Further Reading

(1) Reffner, J. A., Kammrath, B. W. (Eds.) Solving Problems with Microscopy: Real‐life Examples in Forensic, Life and Chemical Sciences. John Wiley & Sons, 2023. ISBN: 978-1119788225.

(2) De Forest, P. R.; Pizzola, P.; Kammrath, B. W. Blood Traces: Interpretation of Deposition and Distribution. John Wiley & Sons, 2021. ISBN: 978-1119764533.

(3) Crocombe, R; Leary, P. E; Kammrath, B. W. (Eds.) Portable Spectroscopy and Spectrometry 1: Technologies and Instrumentation. John Wiley & Sons, 2021. ISBN: 978-1119636366.

(4) Crocombe, R.; Leary, P. E.; Kammrath, B. W. (Eds.) Portable Spectroscopy and Spectrometry 2: Applications. John Wiley & Sons, 2021. ISBN: 978-1119636403.

(5) Kammrath, B. W.; Leary, P. E.; Reffner, J. A. Collecting Quality Infrared Spectra from Microscopic Samples of Suspicious Powders in a Sealed Cell. Appl. Spectrosc. 2017, 71 (3), 438–445. DOI: 10.1177/0003702816666286

(6) Moquin, K.; Higgins, A.; Leary, P.; Kammrath, B. Optimized Explosives Analysis Using Portable Gas Chromatography–Mass Spectrometry for Battlefield Forensics. LCGC International 2020. https://www.chromatographyonline.com/view/optimized-explosives-analysis-using-portable-gas-chromatography-mass-spectrometry-battlefield-forensics

(7) Leary, P.; Kammrath, B.; McMahon, M.; Massey, P.; Lieblei, D. A Comparison of Portable Infrared Spectrometers, Portable Raman Spectrometers, and Color-Based Field Tests for the On-Scene Analysis of Cocaine. Spectroscopy 2018. https://www.spectroscopyonline.com/view/comparison-portable-infrared-spectrometers-portable-raman-spectrometers-and-color-based-field-tests

(8) Leary, P. E.; Kizzire, K. L.; Chan Chao, R.; Niedziejko, M.; Martineau, N.; Kammrath, B. W. Evaluation of Portable Gas Chromatography–Mass Spectrometry (GC–MS) for the Analysis of Fentanyl, Fentanyl Analogs, and Other Synthetic Opioids. J. Forensic Sci. 2023, 68 (5), 1601–1614. DOI: 10.1111/1556-4029.15340

(9) Ryland, S. G., & Suzuki, E. M. (2012). Analysis of Paint Evidence. Forensic Chemistry Handbook, 131–224.