How Portable Instruments are Changing Forensic Investigations

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“With portable instruments, we really have a chance to bring the science to the scene,” Dr. Kammrath says. “We can get science involved in the decision-making stages. That can be incredibly valuable.”Dr. Brooke Kammrath, Professor, University of New Haven, Forensic Science Department

The rise of portable instruments is blurring the boundary between the crime scene and the lab.

Handheld devices are not new to investigations—consider the magnifying glass or the breathalyzer test—but their growing complexity and efficacy are changing the way modern investigations are conducted. Samples that previously needed to be sent to a laboratory can now be analyzed at the scene. Combined with an increasingly skilled investigative workforce, this cuts down on processing times and opens up exciting new possibilities for criminal justice and forensic science fields.

Portable instruments are changing the way modern investigations are conducted, but they come with their own challenges, too. To learn more about how portable instruments are being used now, and what they might look like in the future, read on.

Meet the Expert: Brooke W. Kammrath, PhD, ABC-GKE

Brooke Kammrath

Dr. Brooke Kammrath is a professor in the Forensic Science Department at the University of New Haven and executive director of the Henry C. Lee Institute of Forensic Science. She is an internationally recognized forensic science researcher and mentor, with a varied research agenda that includes the uniting of microscopy with spectroscopy, the identification and characterization of microscopic samples of forensic interest, the statistical analysis of trace, pattern and impression evidence, portable instrumentation, and investigations into the significance and impact of physical evidence.

Dr. Kammrath is a past president of the New York Microscopical Society (NYMS), and on the Governing Boards of NYMS, the Society for Applied Spectroscopy (SAS), and the Eastern Analytical Symposium (EAS). She serves as an associate editor for the Journal of Forensic Sciences and Applied Spectroscopy Practica. She is also a certified criminalist by the American Board of Criminalistics (ABC).

The Evolution of Portable Instruments in Forensics

“The use of portable instruments is actually quite extensive,” Dr. Kammrath says. “The first portable spectrometer was for the military—ion mobility spectrometry (IMS)—but even before that we were using Kitagawa tubes, which are gas identification tubes, and there were other things people were using in the field to identify materials.”

An important step forward occurred in the late 1990s when a team of scientists at SensIR Technologies, Inc. pioneered a portable infrared system that brought lab-level spectroscopy to the field in a suitcase-sized object. Initially, it did not find widespread use. In investigations, spectroscopy remained largely confined to the lab—until a sense of urgency around on-site crime scene analysis arose several years later.

“After 9/11 and the Amerithrax attacks, all of a sudden there was a huge recognition of the need for portable instrumentation in the field,” Dr. Kammrath says.

Today’s most advanced portable instruments can conduct sophisticated on-site spectroscopic analysis. That can be particularly valuable when drugs, explosives, or other hazardous substances are suspected. On-site analysis can save time, and lives. And, when used correctly, these portable instruments help ensure that science and the scientific method are leading investigations.

Challenges in the Use of Portable Instruments in Forensics

Part of the appeal of today’s advanced portable instruments is that they do not require an expert to operate them. The user interface is often relatively simple—most even have a video screen that walks the user through the process, step-by-step. But just because the instrument is easy to use, doesn’t mean it’s foolproof.

“One challenge is with informed sample selection,” Dr. Kammrath says. “What do you sample, and how do you interpret the data?”

For a law enforcement officer who finds a bag of white powder, it might not be too puzzling what to sample or look for. But even in seemingly straightforward cases, human bias can still creep in. Dr. Kammrath points to the case of Shai Werts. Werts was pulled over by police officers, who proceeded to scrape a white material off the exterior surface of his car and test it on-scene for the presence of illegal substances. The result of the test came back negative, but the officers misread the results and arrested Werts for possession of cocaine—when what they’d tested was actually bird excrement.

“The other issue is with interpretation,” Dr. Kammrath says. “A lot of samples can give challenging results, and the algorithms that are used to come up with whether a substance is fentanyl or not, for instance, aren’t always correct. They’re getting better, but there are still times where it’s questionable. So the person who is running the test needs a way to ensure or understand the results that the instrument gives.”

Some portable instruments have implemented “Reachback,” which allows for sampled data to be sent, 24-7, to a chemist for further analysis. Currently, that Reachback is often coordinated through the instrument companies themselves, but such a capability could be configured to be sent back to a specific forensic lab—effectively connecting forensic scientists, remotely, to the scene. But there’s still a limit to what’s possible on-scene right now.

“Not all portable instruments are the same as their benchtop versions,” Dr. Kammrath says. “Portable Raman spectrometers are not as good as the benchtop Ramans. The portable mass spectrometers don’t have the same resolution that the benchtop systems do. So they’re still going to be, in my book, presumptive tests that need to be sent back to the lab eventually for confirmatory testing.”

The technology will continue to get better. Some types of portable instruments, especially portable infrared systems, are already as good as their benchtop equivalents. Expert chemists and engineers are continually working on miniaturizing critical hardware elements. More and more parts of the lab will continue to move into the field—but not all of them.

Portable instruments are best used when they can provide actionable information. A quick analysis of a thread left on a body at a scene might reveal it to be made of red and blue fibers; that information passed onto officers canvassing the area near the crime scene can be a crucial detail. But knowing whether the thread is made of polyester or nylon or cotton would be less actionable. It’d also take more time, and might even distract or lead to false positives.

“I’m not a person who thinks that we should bring the whole lab to the field,” Dr. Kammrath says. “It depends on the application.”

The Future of Portable Instruments in Forensics

Today, portable instruments are most commonly used when time and safety are at a premium in an investigation. If drugs are present on the scene, a suspect is liable to be detained right away, making accurate on-site testing consequential. Explosives and other hazardous substances present immediate safety risks. And in arson investigations, on-site analysis is often crucial in determining a fire’s origin. But as the prominence of portable instruments grows, so will their array of applications.

“There are a large number of applications for portable instruments and a lot of areas of potential research,” Dr. Kammrath says. “It’s very exciting.”

There are hundreds of thousands of portable instruments already deployed in the field, not only in forensic science but also in agriculture and food science. More use begets more research begets more use—and research in portable instruments is bringing science fiction closer.

“The ideal portable instrument would be rapid, reliable, and create a reviewable record,” Dr. Kammrath says. “The Holy Grail is the tricorder.”

The tricorder, popularized in Star Trek, is a fictional device that quickly and non-invasively analyzes all the properties of the sample it scans. It can identify solids, liquids, and gasses—both as pure substances and in all ranges of concentration. It provides no false positives and no false negatives. And, crucially, it combines and cross-references its analyses, drawing conclusions from multiple data sets.

“We’re nowhere near achieving that today,” Dr. Kammrath says. “I think we’ll always need a toolbox approach, where you have more than one instrument, and you need to know the capabilities and limitations of each instrument in order to know which to use at what time.”

While waiting for the tricorder to materialize, the next hurdle for forensic scientists is getting current, non-fictional portable instruments into the hands of first responders. Cost and complexity are often cited as challenges, but these devices are not as expensive as one might think: over the long run, they may save law enforcement agencies money.

Portable instruments also have uses in traditional laboratories, which can be used for presumptive testing. Their smaller size, ease of use, and reproducible data are all valuable to the forensic scientist working in the lab. But more forensic scientists will be needed in the field, too, especially as portable instruments grow in sophistication. It’s not just the lab moving into the field, but forensic scientists and science itself.

“With portable instruments, we really have a chance to bring the science to the scene,” Dr. Kammrath says. “We can get science involved in the decision-making stages. That can be incredibly valuable.”


Matt Zbrog

Matt Zbrog is a writer and researcher from Southern California. Since 2018, he’s written extensively about the increasing digitization of investigations, the growing importance of forensic science, and emerging areas of investigative practice like open source intelligence (OSINT) and blockchain forensics. His writing and research are focused on learning from those who know the subject best, including leaders and subject matter specialists from the Association of Certified Fraud Examiners (ACFE) and the American Academy of Forensic Science (AAFS). As part of the Big Employers in Forensics series, Matt has conducted detailed interviews with forensic experts at the ATF, DEA, FBI, and NCIS.