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Faster and More Efficient Forensics

Tue, 07/12/2011 - 11:44am
Mike May

Advanced tools that collect and analyze samples combat crime.

The science of forensics expands faster than the number of crime-related programs on television. In fact, Colin Thurston—director of product strategy, process industries at Thermo Fisher Scientific—says, “One of the key challenges in forensics today is the breadth and volume of the testing required for forensics labs.” He adds, “As scientific techniques become more sensitive and applicable to the forensics space, the demands on labs become higher and higher.”

BST June 2011 Cover ImageThat increasing pressure requires labs to find ways to do more with less—analyze more DNA and do so faster and at less expense. To reach those goals, forensics labs need new tools that help them collect more samples, analyze them at higher throughout, and also churn out more accurate results.

Collecting Samples
When asked about the most difficult types of samples to collect, James D. Frost III, president and CEO of BioTX Automation, says, “It’s probably touch samples,” such as skin cells left on something that a criminal touched during a crime. BioTX makes a vacuum system that can be used with touch DNA and other samples.

Once a forensics lab starts analyzing the samples, pipetting can create errors in multiwell plates. To reduce that problem, Frost’s company developed its WellAware system. A technician places a multi-well plate on an Android-based tablet, which keeps track of what is in each well.

“Software lights up the wells one at a time as you go through the steps in an assay,” Frost explains. “It can handle up to two 384-well plates,” he adds.

Qiagen Rotor-Gene Q thermocycler
The Rotor-Gene Q thermocycler and the Investigator Quantiplex Kit speed up DNA analysis. (Source: Qiagen)

Identifying DNA
“DNA analysis in forensics usually includes at least 16 amplification reactions,” says Keith Jolliff, senior marketing manager for applied testing at Qiagen. Before investing the time, effort, and money in that process, it’s important to know if a forensic sample can be successfully analyzed.

In March, Qiagen launched its Investigator Quantiplex Kit, which can be used to make sure that a sample contains enough DNA to fingerprint. Using real-time PCR, this kit plus Qiagen’s Rotor-Gene Q thermocycler takes just 50 minutes to get an answer with a sensitivity of 1 picogram per microliter. That’s 54% faster than any other kit, according to Jolliff. Even without the Rotor-Gene Q, this kit runs 46% faster than others. “That’s because of the unique reaction chemistry and the type of probes being used,” he adds.

This kit also includes an internal control that tests for PCR inhibitors. As Jolliff says, “If the assay says there’s enough DNA and the internal control is amplified, you’re likely to get a profile from that DNA.”

Genetic Overload
For DNA-based profiling, Benjamin Krenke, global product manager for the genetic identify team at Promega, says that one of today’s biggest challenges is simply keeping up with the workload. “A large part of the load comes from databasing, which is DNA analysis of convicted offenders,” he says. Today’s crime labs use this database of DNA profiles to help resolve unsolved cases. However, many states keep expanding the number of criminals who must be analyzed. “We’re seeing a progression of legislation,” Krenke says, “from storing DNA profiles for offenders convicted of violent crimes to all felons and even specific types of arrests.” He adds, “The number of samples submitted to a state crime lab can double or even triple with such changes in legislation.”

Promega PowerPlex 18D system
The PowerPlex 18D system directly analyzes DNA from buccal or blood samples taken from punches of a Whatman FTA card. (Source: Promega)

To help forensics labs handle the increasing workload, Promega developed its PowerPlex 18D system. This technology works directly on buccal or blood samples taken from punches of a Whatman FTA card, and it provides results in just 90 minutes. According to Krenke, “This system will cut time by over 40% in some labs. So a lab can increase the throughput without a significant change in headcount or budget.”

Beyond developing new technologies, Promega also runs the International Symposium on Human Identification, which is advertised as a place to “learn, share & network with your colleagues in the field of DNA forensics.” (For more information, visit www.ishi22.com.)

Reaching for More with Raman
Various spectroscopic techniques rely on light-induced changes in atomic-bond energy in molecules. According to Mike Garry, Fourier transform-infrared spectroscopy product manager at Thermo Fisher Scientific, “Infrared and Raman spectroscopy have the unique ability to provide characteristic molecular ‘fingerprints’ of materials—such as fibers from clothing or ink from documents—that can be used to identify them.”

To help researchers get more from such approaches, Thermo Fisher Scientific increased this technology’s sensitivity with surface-enhanced Raman spectroscopy in their DXR Raman microscope. In addition, Garry says, “The multi-component searching capability provided in our OMNIC Specta software allows the forensic scientist to better identify evidence of samples that are mixtures, which is a high percentage of the samples they analyze. This mixture-searching capability makes the analysis less subjective and provides higher confidence in the results.”

Leaning on LIMS
As expectations of forensics labs and their workload increase, a frequent lack of increasing funds demands a search for more efficiency. As Thurston explains it: “Forensics labs are facing the challenge of lots of other industries, which is providing more expertise and throughput without added investment.”

One way to do that is to find less expensive ways to track data and analysis, which is precisely the aim of a laboratory information management system, or LIMS. For one thing, a LIMS makes it easy for a forensics lab to track sample custody. “Our Nautilus LIMS,” says Thurston, “can automatically download the data to an instrument and keep track of a sample’s position in, say, a plate or a rack.” For example, the Nautilus LIMS can control DNA-sample loading in a 96-well plate, even making sure that the right sample is in the right position before processing. “Once the sample is processed,” Thurston says, “our LIMS will directly attach the results to the location from which the sample was taken in the plate. It’s a closed loop—from the technique and method to processing the sample.”

Mascara on an eyelash magnified at 200 times
Mascara on an eyelash, magnified here at 200 times can be analyzed with infrared spectroscopy to distinguish some brands. (Source: McCrone Associates)

Don’t Bat an Eyelash
Blinking could incriminate some of tomorrow’s criminals. When teaching a hair-comparison class, Kristen Wiley—a senior research microscopist at McCrone Associates, the analytical services arm of The McCrone Group—lost an eyelash and it dropped under her scope.

“I thought I didn’t wear much makeup,” she says, “but my eyelash was still relatively coated with mascara.”

She started to wonder if the mascara could turn into evidence. Wiley removed the mascara from her eyelash and from lashes donated by two of her coworkers—all three wearing different brands of mascara. Then, an infrared spectroscopist showed that each brand generated a different IR signature. In fact, Wiley could even tell apart some of the brands with polarized light microscopy. “Two brands had birefringent particles and one didn’t,” she says.

Richard Bisbing, executive vice president at Hooke College of Applied Sciences, the education division of The McCrone Group, adds that mascara stains could also be taken from other surfaces, such as a pillowcase. “If you have three possible people under suspicion,” he says, “the brand of mascara might be used to limit your population of interest.”

Advanced technology often brings new kinds of samples into forensics. Likewise, labs can explore more samples—doing it all faster and more accurately.

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