Andrew Laurence, Ph.D., Shannon Ferguson, Ph.D.

Listen to Andrew Laurence and Shannon Ferguson discuss their work:

She was found in a southwest Ohio ditch in 1981, auburn-haired, shoeless and dressed in jeans, a sweater and a fringed buckskin jacket. It appeared her body had been dumped. But who was the young homicide victim, known for decades thereafter only as “Buckskin Girl”? 

Marcia King, 21, would not be identified until 2018, a result of developments in science that included pollen analysis, a relatively new tool used by the federal government’s only forensic palynology program. In a U.S. Customs and Border Protection laboratory in Chicago, Andrew Laurence, 33, and Shannon Ferguson, 32, analyze pollen – from clothing, a truck’s air filter, a confiscated kilo of cocaine, a packet of fentanyl or a blanket – to tell where a person or an object has been, its likely origin, even its travel route. 

Using the same kind of microscopic pollen and spores that make people sneeze or aggravate allergies, Laurence and Ferguson analyze pollen grains to help solve, stop and understand crime, providing valuable clues as to a victim’s or assailant’s identity, and the origin and transit routes of seized narcotics.  

“The CBP team, led by scientists Andrew Laurence and Shannon Ferguson, have used their analysis of microscopic pollen and spores to determine production locations and transit routes of drugs intercepted at ports of entry,” said Patricia Coleman, CBP’s deputy executive director. “The palynology program also is regularly used to reconstruct the travel histories of persons of interest who may have ties to terrorism or transnational criminal organizations…and has assisted local law enforcement in child homicide cases.” 

While CBP’s pollen analysis alone has not directly solved drug smuggling and homicide cases, it has provided critical information that has helped law enforcement authorities bring criminals to justice in hundreds of cases. 

Pollen, whether spread from a species of tree, plant or flower, is abundant and immensely unique in its geography. Invisible to the naked eye, it also is abnormally resilient.  

Marcia King’s clothing, for example, still had grains of oak, spruce and hemlock, indicative of the eastern United States, but also ephedra and mesquite, western pollens that looked fresher, Laurence said.  

“Our analysis showed she had taken a trip out West,” he said. It turned out that King was born in Arkansas, had taken a western trip and lived in Pittsburgh before her murder. This analysis, along with isotope tests of her hair by Ohio investigators, helped others in law enforcement better target their investigation, which ultimately led to a positive DNA identification. 

“We can tell you where something originates from or where it’s been,” Laurence said. “If someone is arrested, our pollen analysis can tell law enforcement where the individual traveled and whether they are lying about their travel history.” 

Although the scientists work for CBP, they help fill intelligence gaps for other law enforcement agencies and governments. “They have been useful in dozens of cases for the National Center for Missing and Exploited Children, and the National Missing and Unidentified Persons System, and have assisted a range of law enforcement agencies,” Coleman said.  

“We’ve even done hummingbirds for the Fish and Wildlife Service,” Ferguson said. “There is a subculture in Mexico where they kill hummingbirds, turn them into love charms and then import them into the United States, where the hummingbirds are protected.” 

Pollen analysis has also helped the team discern illegal shipments of antiquities from abroad, isolate the geography and environmental conditions under which seized marijuana was grown, and understand that small amounts of fentanyl shipped from Mexico and seized on the U.S. border had a link to China. 

“That means not only is China sending shipments of smaller quantities of pure fentanyl, they’ve also gotten into the illicit smuggling game,” said Robert Harvey, CBP’s supervisory border patrol agent. “We took that to the Drug Enforcement Agency and the Office of National Drug Control Policy, and they fell out of their chairs. It changed the whole paradigm of how they needed to look at this.” 

Laurence, who has a Ph.D. in anthropology from Texas A&M University, was hired by CBP in 2012 on the recommendation from his mentor, Vaughn Bryant, an anthropology professor known as the father of forensic palynology. Ferguson was brought on as an intern in 2015, while still a doctoral student in geology at Louisiana State University. CBP hired her full time in 2017.  

Laurence said he jumped at the opportunity to work for CBP doing the pollen analysis because “literally nobody else in the country is doing this kind of work.” He said it is extremely rewarding to serve the public interest by contributing important information to help law enforcement authorities in their investigations.  

Ferguson said she worked with a professor who introduced her to “the whole world of pollen.” She said she wanted to use the science to do good, “not just to make money in the ‘dog eat dog’ world of private industry.” Ferguson said CBP allows her “to figure out problems” and “help people in the real world right now, and that is amazing.” 

Much of their work involves analyzing pollen picked up by agents in drug investigations. In one case, authorities had seized a cocaine-hauling truck as it tried to enter Canada from Detroit. Analyzing pollen from the truck’s air filter, the palynology team was able to discern that the shipment started in California, but took an oddly circuitous route, collecting tell-tale pollen grains across the United States, rather than driving straight through Washington state to Canada.  

“This is a new science,” said E. Anthony Malana, acting director of CBP’s Laboratories and Scientific Services, “and Andy and Shannon are at the forefront.”