SCIENCE & TECHNOLOGY ACS
MEETING
NEWS
evidence." In 1995, when Kelly investigat ed the bombing of the Alfred P. Murrah Federal Building in Oklahoma City, the assessment took more than three weeks and covered 20 sq blocks. Evidence from the bombing of Pan Am Flight 103 over Lockerbie, Scotland, was gathered over more than 50 sq miles, according to Kelly Investigators rely on handheld and portable devices when looking for trace evidence over such a large area, Kelly said, BETHANY HALFORD, C&EN WASHINGTON adding that "our old pal, the dog," is still one of the best detection systems that crime-scene investigators use. They also IKE MOST PEOPLE, WHEN AMERIthey were the work of the same terrorist or employ field instruments such as portable can Chemical Society members an ganization, but it was up to Kelly and his infrared and Raman spectrometers. alyze evidence from a crime scene, coworkers to determine whether the two theyusually do sofromthe comfort events were related forensically Naturally, instrumental analysis isn't oftheir couch during an episode of limited to fieldwork. At his lab in QuantiAfter visiting both scenes and process the T V series "CSI: Crime Scene Investigaco, Va., Kelly has access to an entire battery ing thousands of pieces of trace evidence, tion."Thanks to the Committee on Science, of high-tech tools such as thermal energy the investigators were able to physically a roomful of armchair criminalists at last analysis, ion-mobility spectrometry, ion prove that the attackers worked in har month's ACS national meeting in San Diego chromatography stable-isotope ratio analy mony They were also able to use the evi got to vicariously duck behind the yellow sis, and direct analysis in real time—to dence to eliminate potential suspects. police tape and see how chemistry clar m name just a few " % u really have to be ifies criminal investigations. 2 well-versed in instrumental analysis to | do this kind of work," he told the "Maybe we could call this 'CSI: ACS' S crowd. or something like that," joked Luis A. < Echegoyen, a chemistry professor at | SYMPOSIUM ATTENDEES also got a South Carolina's Clemson University during his opening remarks at the ΐ lightning-speed primer on the future symposium "Finding Criminals with 1 of technology for detecting explosives Forensic Chemistry" Echegoyen coΪ; and chemical warfare agents in the field, organized the symposium, which was 2 courtesy of University ofArizona chemcosponsored by the Divisions of Ana | istry professor M. Bonner Denton. lytical Chemistry and of Chemistry & S Denton discussed how instruments the Law It gave attendees an idea of | once considered too large and expen the current and emerging analytical sive for practical use by law enforce techniques that forensic chemists use. ment officers are becoming cheaper, Today, "science is playing a much more portable, and more sensitive. In greater role overall in criminal investi particular, Denton spoke about a de gations" than in the past, remarked vice his group has developed that he Ronald L. Kelly, a forensic chemist compared to a Star Trek-style tricorder, with the Federal Bureau of Investiga which could be used by airport bag tion's Explosives Unit. Kelly often trav gage screeners to scan luggage for il els to the sites of deadly bombings and licit drugs, explosives, or other dan explosions to help investigators gath gerous chemicals. er trace evidence. He then analyzes The device is a pocket-sized ionthis evidence to figure out what type CRIME SCENE After the bombing of the U.S. mobility spectrometer. Airports al of explosives and ignitable liquids were Embassy in Nairobi, Kenya (pictured here), ready use ion-mobility spectrometers used in the attack. The information forensic chemist Kelly gathered trace evidence to detect explosives—it's that micro can point to the material's source and that enabled him to link the bombing to a wave-sized device into which trans sometimes link the incidents to spe simultaneous terrorist attack in Dar es Salaam portation safety officers will insert cific terrorist organizations. swabs that they use to mop up residues Tanzania. on a briefcase or camera. In 1998, for example, Kelly was part Denton said that, by improving the in Tracking down evidence from an ex of the team that investigated the bomb strument's electronics, his group has man plosion is no simple task, Kelly noted. "%u ings of US. Embassies in Nairobi, Kenya, aged to shrink it and make it 1,000 times and Dar es Salaam, Tanzania. The nature of have evidence going all over the place," he more sensitive than the devices used at airsaid. "Halfthe challenge is just locating the the simultaneous attacks suggested that
CHEMISTRY'S CRIME FIGHTERS
Forensic scientists tell how they help solve crimes using a variety of analytical techniques
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ports. The device is so sensitive, Denton said, that it could detect traces of explosives in the air that passes over a person who's handled them. Taking circuitry originally developed for infrared astronomy, Denton managed to boost the spectrometer's readout circuitry "This change in readout electronics is key to the vastly improved sensitivity It boosts the signal while lowering the noise," he said. "This is the first radical change in ion detection since the 1930s." University of Utah biology professor James R. Ehleringer spoke about his work using stable-isotope analysis to determine where people and substances originate. The technique can also be used to determine if two identical chemical substances come from the same source. Ehleringer uses mass spectrometry to examine the ratio of stable isotopes, such as carbon-12 and carbon-13, in a compound. Depending upon the element he looks at, the ratio can point to a substance's source. For instance, the food industry uses stable-isotope testing to see if an unscrupulous juice maker has swapped corn syrup for the grape juice sweetener listed in the ingredients. The sugar from both is chemically identical, but molecules have different stable-isotope ratios depending on whether they come from grapes or corn. The Drug Enforcement Administration already employs Ehleringer's analytical technique to find common sources for narcotics. AT THE ACS MEETING, Ehleringer said that by analyzing the ratio of stable oxygen isotopes in a person's hair, he can often tell where that person lives. That's because the ratio of oxygen-18 to oxygen-16 in drinking water varies substantially from region to region. The water we drink is incorporated into our bodies, leaving the telltale signature of our hometown in our hair. Ehleringer's technology isn't easily thwarted either: Hair dye has almost no effect on the analysis, and limiting your drinking water to the bottled variety won't fool the technology because the source of most bottled water is close to where the water is ultimately consumed. The oxygen-based analytical method can be used to help identify aJohn Doe in the morgue or to determine where a biological agent such as anthrax was grown, Ehleringer said. No symposium on forensic chemistry would be complete without a discussion of D N A . During the afternoon session, San Diego County Superior Court Judge George W Clarke noted that the ubiquitous molecule has become such a staple of T V court trials—both real and fictional— WWW.CEN-0NLINE.ORG
EDUCATION
Academic Programs Gear Up To Meet Rising Interest In Forensic Science
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any science fans would complain that Hollywood has long given scientists a bum rap—they are usually portrayed as obsessive, arrogant, or even downright evil. But thanks to a recent glut of forensic-themed television shows, at least one field of science is benefiting from an image makeover. Colleges and universities across the country have seen a surge in applicants who want to build a career in forensic crime solving. Demand is generating supply, and more educational institutions are starting up dedicated forensic science programs. "I'd say the number of programs has probably tripled in the past five years," says Charles Tindall, chair of the chemistry department and director of the 30year-old forensic science program at Colorado's Metropolitan State College of Denver. Currently, the American Academy of Forensic Sciences (AAFS) counts 55 U.S. academic institutions offering a bachelor's degree with a forensic science concentration, including 18 programs that are housed in chemistry departments. Nine of these schools also offer master's-level programs, and an additional 70 schools on the AAFS list only offer forensics master's. According to Tindall, the number of programs will continue to rise to accommodate what he calls "tremendous interest" from students nationwide. "As an example, we were the only forensics program in Colorado for many years, but now there are two more operating and another in the works," he says. Max M. Houck, director of the Forensic Science Initiative at West Virginia University, Morgantown, says his school started its program in 1999 with only four students. It has since grown to nearly 400 students—the most popular major on campus. To ensure that quality accompanies the rise in quantity, AAFS started the Forensic Science Education Programs Accreditation Commission (FEPAC) in 2003. Programs that seek accreditation must complete a self-evaluation and arrange a site visit to show that they meet certain standards identified by a
National Institute of Justice guide on forensic science education and training. To date, FEPAC has issued accreditation to 10 schools and is working on the 2005 applications. The accreditation standards allow for variations in how a program is administered, but require a stronger base in the sciences—especially chemistry—than traditional forensics curricula have incorporated. "Forensic science programs used to be looked down on by crime lab directors," Tindall says. Too many of the programs didn't cover science at all, so labs were more interested in hiring candidates with undergraduate science degrees. "Our program offers the same thing as a basic science degree," Houck says. "A graduate should be able to do any job a B.S. in chemistry could." Even with such standards in place, an undergraduate degree in forensic science might not be the best path for everyone. Tindall recommends that undergraduates who think they want to go on to graduate school choose a chemistry or biochemistry undergrad major and look for a master's program in forensics. "The big advantage for people in a program like mine will be finding internships," Tindall says. Specialized undergraduate programs often have connections with people working in the field and offer internship and networking opportunities that might not accompany a pure science degree. The real mystery is whether enthusiastic new forensics degree-holders will find work in their chosen field, given forensic science's historic lack of funding combined with a possible overload of job seekers. The American Society of Crime Laboratory Directors estimates that crime labs will need 10,000 new forensic scientists over the next decade to address their case backlog, a need that should be easily met by the projected wave of graduating students. "The number of programs existing will likely provide an excess of candidates for these jobs—but this is a good thing," Tindall says. "Labs will have plenty of qualified candidates to choose from."-VICTORIA GILMAN
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SCIENCE & TECHNOLOGY that in their deliberations, juries will often ask why D N A evidence wasn't presented, even if D N A has no bearing on the case. Two chemists,John M. Buder of the National Institute of Standards & Technology and Bruce R. McCord of Florida International University, Miami, spoke about historical and current forensic D N A research. "DNA analysis is both sensitive and specific," McCord said, "and that warms an analytical chemist's heart." Neverthe-
graded samples. The technology he said, helped investigators identify the victims ofthe WforldTrade Center attacks in 2001. McCord is also working to develop a tool kit that would help investigators detenriine what type of D N A analysis is best suited to their sample. D N A analyses consume both time and money, and McCord thinks his tool kit could streamline the huge backlog of D N A evidence waiting to be processed.
AS STATE-OF-THE-ART as these new techniques and instruments may be, forensic chemists often rely on more mundane chemical evidence to link a suspect to a crime scene. José R. Almirall, a chemistry professor at Florida International University and the symposium's other co-organizer, uses glass trace evidence to help solve criminal investigations. Almirall first got interested in glass when he worked at the TRACE EVIDENCE Almirall used a specialized Miami-Dade police department. He explained that broken elemental analysis technique to link the glass at glass from a crime scene—for this crime scene to shards of glass found on the example, when a thiefbreaks inperson suspected of breaking into the car. to a house—often ends up on the crime's perpetrator. Investigators can less, he and Butler said scientists still face use those tiny bits of glass evidence to link challenges when analyzing certain types of a suspect to the scene of the crime. D N A evidence. Investigators used to rely on the glass's According to Butler, more than tworefractive index to determine whether thirds of cases based on D N A evidence inor not shards from the suspect and shards volve sexual assault. And one of the biggest from the crime scene were from the same challenges that criminalists face in these piece of glass, or "caninvestigations, he said, is separating epnot be distinguished" in ithelial cells from a female victim from the CSI-speak. These days, sperm cells of the assailant. glassmakers, particularButler and his colleagues have developed a technique that allows them to amplify on- ly automotive glassmakers, have gotten much ly the Y chromosome (originating from the better at making the remale) in these mixed-DNA samples. To do fractive index of glass this, the researchers developed primers that uniform. This makes it copy and amplify regions of D N A that are harder to link glass trace located exclusively on the Y chromosome. evidence beyond a reaButler said that using this method, his group sonable doubt, Almirall can easily pick out the male DNAin a samexplained. ple where the concentration of female D N A is 800 times higher. When Almirall moved from the police departMcCord spoke about the challenge that ment to academia, he thought he might be degraded DNA poses to forensic chemists. able to make the forensic study of glass If a body has been exposed to the elements more precise using elemental analysis. "I for a long period of time or if a bloodstain got interested in characterizing glass as a is old, it's likely that the D N A has degradmaterial," he said. By analyzing glass using ed. At a certain point, the D N A becomes solution-based, inductively coupled plasma too fragmented for routine analyses to mass spectrometry (ICP-MS), Almirall work well, McCord said. found that he could pick up trace-metal In collaboration with Butler, McCord impurities in the glass. developed primers that amplify smaller pieces of DNA, thereby helping forensic Trace metals are introduced during the chemists glean information from these demanufacturing process, often from the
equipment or raw materials. They vary over time and consequently tend to be specific to a particular product and often a certain time frame, Almirall said. To prove the specificity of the elemental analysis, Shirly Montero, a graduate student ofAlmirall's, examined more than 700 different glasses from a variety of sources and more than 200 samples from a glass factory in Wisconsin. All but a handful of the possible comparison pairs were distinguishable by the technique. Furthermore, when Montero and Almirall analyzed 45 different headlights, they found that all of them could be distinguished from each other. The solution-based method is not without its drawbacks, Almirall noted. "Dissolving the glass is very cumbersome. % u need to use hydrofluoric acid and nitric acid," he said. Also, the analysis requires at least a few milligrams of glass that are ultimately destroyed. Recently, Almirall has figured out away to get around these problems by using laser ablation to sample the glass fragments—a technique he borrowed from geochemists. "Now, we can directly sample the glass, and we're only removing 300 ng of material," he said. "That's a big advantage in quantitative analysis." Almirall presented one case study in which ICP-MS analysis was used to link a suspect and a crime scene. At 10 AM one Sunday in Miami Beach, a woman was struck and killed during a hit-and-run incident. A witness identified a black B M W as the car involved. It did not take the police long to find a smashedup, black BMWin a nearby parking lot. But when they tracked down the vehicle's owner, he told police that his car had been stolen the night before. The police had no way to prove he wasn't telling the truth, with the exception of tiny bits of glass they found on the man's clothing, in his bathroom, and in his sink. Almirall was able to use ICP-MS to determine that the glass from the B M W and the glass from the suspect's apartment were indistinguishable. "The glass evidence was the only evidence that tied him to the incident," Almirall said. Almirall is currently trying to use laser ablation ICP-MS to analyze trace metals in paint, ink, bone, and teeth. He joked that this technique must be ready for prime time, as it figured as a plot device on"CSI."H
The police had no way to prove he wasn't telling the truth, with the exception of tiny bits of glass they found on the man's clothing.
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