Getting the dirt on a tree thief
By Michelle Betz
Entomology isn’t the only agricultural
discipline that helps solve crimes. Soil properties are now making
their mark in the world of forensic science. Law enforcement professionals
around the country are finding this evidence to be key in closing
cases.
Brad Lee, now an assistant professor in agronomy,
tapped his knowledge of soil properties to help solve a case of
stolen palm trees. While working on his doctorate at the University
of California-Riverside, Lee and his colleagues at the Soil Mineralogy
Laboratory were asked to lend their expertise with mineral and physical
characteristics of the soil in a police investigation.
“It was a new application of fundamental
soil mineralogical and morphological techniques,” Lee says.
While soil properties are commonly examined in agriculture and other
areas, such as septic system placement, this was Lee’s first
time using these basic elements in a criminal investigation.
Scientists at the lab were contacted in April
1997 by the San Diego County District Attorney’s Office, which
was investigating the theft of rare palm trees. Lee didn’t
hesitate at the chance to become the Sherlock Holmes of soil. “My
first reaction was to quickly say ‘yes,’” he says.
“The process was a simple application of scientific method.”
The soil scientist turned sleuth was taken to
the suspected thief’s home located in a modest subdivision.
Lee became suspicious as soon as he arrived. “It looked a
little odd as several palm trees were planted in the small lot,"
he says. “These were rare, expensive trees grown by an exclusive
nursery and unlikely to be found in the average subdivision.”
This circumstantial evidence helped the scientists
locate 33 palm trees believed to belong to the nursery from which
the palms were stolen. Soil samples taken from the root balls were
tested to see if there were similarities between the soil in the
root balls and the distinctive potting soil that was used by the
nursery. Lee used these tests to examine soil color, particle size,
mineral density and heavy mineral grain counts.
Lee and his colleagues found that the grains
in 25 of the root balls were consistent with the mineral makeup
of the nursery’s potting mix. This meant that at least 25
of the 33 palm trees found at the residence were stolen from the
nursery. This evidence sealed the deal and was enough to convict
the criminal.
“The circumstantial evidence was overwhelming;
however, the prosecution lacked a tangible link to the victim’s
palm trees until the soil investigation was completed,” Lee
says. Case closed.
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