Greenbottle flies sit on a petri dish. (credit: David Hecker/AFP/Getty Images)

Greenbottle flies sit on a petri dish. (credit: David Hecker/AFP/Getty Images)

HOUSTON (AP) – The pungent smell aside, it was the buzzing sound — just a bit softer than a beehive — that assured Michelle Sanford there would be a lot of evidence to collect.

After a short trek through the brush in the east Harris County woods, her notion was confirmed. Lying in the thicket, decomposing human remains were swarmed by flies. And the body was covered from head to toe in maggots.

As a forensic entomologist at the Harris County Institute of Forensic Sciences, Sanford specializes in what these insects can reveal about a crime scene.

For her, the fly larvae crawling on the body that spring day were more than just the result of decaying human remains. They were crime scene evidence.

Every year, the Harris County Institute of Forensic Sciences examines about 300 cases involving bodies with moderate to severe decomposition. In incidents such as these — where little forensic evidence may be present — insects around the body can often be the only way to determine how much time has passed since the victim’s death, as well as other information pertinent to a criminal investigation.

This is in part what prompted the agency to hire Sanford in January, making them the only medical examiner’s office in the United States to employ a full-time, in-house entomologist, officials told a Houston newspaper.

“You really have to have the experts there making their initial assessments as the investigation is going on,” said Jennifer Love, forensic anthropology director at the agency. “To send the specimens out afterward, you just lose so much information.”

Generally, forensic investigators collect insect specimens during an autopsy and send them out to contracted entomologists at universities. Sanford’s position is unique in that she collects her own evidence, often during the initial investigation.

“It’s really awesome. I really like this job,” said Sanford, 35, who received her doctorate in entomology from Texas A&M University in 2010.

Since arriving at the agency, Sanford has analyzed evidence in 65 cases, more than half of which she collected at the scene. Her work typically involves determining the time that has elapsed since death, which she does by determining the flies’ stages of development, the species and the temperature.

Sibyl Bucheli, an assistant professor of biology at Sam Houston State University, who specializes in forensic entomology, said insects are some of the most complex biological beings and the field is one that requires incredible expertise — telling the difference between two species of flies can come down to a detail as small as whether one has eyelashes.

“If you’re not trained to look for those, that can be a really frustrating endeavor,” said Bucheli, who has consulted on the entomological findings in criminal investigations. “So to have somebody on board who understands the insects and understands the process of evidence collection, can really just make the whole process much more efficient.”

She also noted that having the evidence collected by a forensic entomologist at the scene makes it more reliable in criminal cases because there is less room for error during collection.

“If you’re not collecting the evidence correctly, you’re not going to be collecting specimens that can be used in court,” Bucheli said.

In a case in February, Sanford recalled spotting maggots on four different parts of the body. She collected specimens from all the locations, something that might not have been obvious to untrained eyes.

Later, after analyzing the evidence in her lab, she was able to determine that the maggots were not only all different species, but at separate stages of development, with the oldest larva on the victim’s head.

“The oldest ones would have been the first to arrive,” said Sanford. “So that would have been the minimum postmortem interval.”

Entomological findings can go beyond helping to determine a time of death. Sanford is also collaborating on a research project with the institute’s forensic genetics department in which insects could potentially be used to determine a victim’s identity.

Because maggots feed on their hosts, they collect the victim’s blood, Sanford said. That blood can be extracted and sent to the genetics department for traditional DNA sequencing to try to identify the victim. The medical examiner’s office is trying to develop the process to include it in standard operating procedures.

“Nobody’s ever done that before for maggot contents,” she said. “So that’s really cool.”

Entomological findings can also contribute to public health.

Sanford recalled a case of a victim who died from an insect sting, but hospital personnel were unclear as to what kind. Under a microscope she saw barbs on the stinger, indicating it was a honey bee.

“I don’t know if they were killer bees or regular bees, but if they were looking for the hive that attacked this person, then they could at least take the proper precautions when they moved it,” she said.

Sanford’s love of bugs began during her early college days at the University of California, Riverside, where she received a bachelor’s degree in biology and master’s in entomology.

Afterward she got a job trudging through wetlands, studying the mechanics of mosquito populations.

She envisioned entering academia and never imagined her passion for insects would lead to a job dissecting crime scenes.
She jumped at the opening in Harris County.

“As an academic you’d just be writing papers, but to me it’s much more satisfying to see people use it right away,” she said.

While almost all insects interest her, she said there is one bug she tries to avoid: “Cockroaches, especially the ones that fly at you.”

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