The Scientist Using Bugs to Help Solve Murders

Photographs by Guido Gazzilli and Claire Martin

Paola Magni didn’t plan on getting involved in her most infamous case. As a forensic entomologist, she researches how insects and related creatures found at crime scenes can help investigators solve mysteries. She frequently works with public health officials and coroners, who, perhaps surprisingly, are often repelled by vermin, critters and crawlers. “Pathologists hate bugs,” she says of the doctors who examine corpses. But her comfort with these widely loathed creatures, combined with a talent for communicating forensic concepts to the public in press interviews and on social media, have propelled her to the forefront of innovations in forensic biology. She has consulted on dozens of homicide cases and suspicious deaths all over the world. In association with the local health service, she established Italy’s first forensic entomology laboratory, then housed in the Turin morgue. A smartphone app she created called SmartInsects, which helps investigators identify bugs and guides them in how to collect samples, has been downloaded more than 40,000 times, mainly by pathologists, law enforcement officers and students. And by applying her expertise to all the living organisms that arrive opportunistically at crime scenes like uninvited party guests, from flies to barnacles, Magni has become a leading figure in the burgeoning field of aquatic forensics, which extends the science of criminal investigations to evidence found in bodies of water.

But in 2012, before she became an international figure, she was still completing her doctorate in biology in her native Turin, in northern Italy. One November morning that year, a passerby spotted a teenage girl lying face down near Lake Bracciano, 400 miles south of Turin. The lake, a tranquil spot where unusually friendly swans compete with ducks and geese for bread tossed by people on the shore, attracts residents from nearby towns and day-trippers from Rome, about a 45-minute drive south.

The body was identified as belonging to 16-year-old Federica Mangiapelo, from the nearby town of Anguillara Sabazia. There were no major signs of trauma or foul play, but the young woman’s shoulder was dislocated, her jacket was half-removed, and her handbag and cellphone were missing. Her blond hair, clothes and shoes were wet, but that didn’t necessarily indicate she’d been in the lake; the preceding night had been rainy, after all. An autopsy showed that she had suffered cardiac arrest and died four hours before the cyclist found her. In the absence of hard evidence suggesting otherwise, authorities concluded she had died of “natural causes,” perhaps related to the epilepsy she’d reportedly suffered as a child. But Federica’s family was adamant that their daughter, who as far as they knew was perfectly healthy, could not have suddenly died in such mysterious circumstances, and they worked to keep the case alive in the media.

The 2012 murder of Federica Mangiapelo might have gone unsolved—if not for Magni. Courtesy Mangiapelo Family / LaPresse via Zuma Press

Coincidentally, Magni had given a presentation on forensic aquatics at a training academy of Italy’s Carabinieri, the country’s military police, shortly before Federica died. One young police officer in attendance ended up assigned to Federica’s case. Given the media coverage emphasizing her family’s insistence that she could not have died of natural causes, he recommended to his superiors that they contact Magni, to see if she might have a novel method of determining what happened on the lakeshore the night Federica died.

Magni wasn’t sure she could help, but she offered to try. “Every contact leaves a trace with its environment,” she told me recently, paraphrasing a principle of forensics commonly attributed to Edmond Locard, a French criminologist who died in 1966. In Federica’s case, it might be possible to tell whether the girl had been in the lake, perhaps against her will. And if she had been in the lake—what other clues would have unwittingly been left behind?

People have known since at least the 13th century that insects and other unpopular creatures can help solve mysteries. In 1247, Sung Tz’u, a Chinese judge and death investigator for criminal courts, wrote what is considered the world’s first forensic handbook, a volume called The Washing Away of Wrongs. The book tells of a farmer found stabbed to death with a sharp object near a rice field. The next day, investigators instructed suspects to place their sickles on the ground. Flies flocked to just one of the blades, enticed by traces of blood invisible to the human eye. Faced with this evidence, the murderer confessed.

The first modern use of forensic entomology is thought to have occurred in 19th-century France, when a doctor analyzed the remains of a child found in an apartment building. By examining the fly larvae and moth pupae on the corpse and using his understanding of their life cycles, he concluded that the child had died between eight and ten months before the body was discovered. Based on his report, the apartment’s current occupants were exonerated, and police instead arrested a couple who’d lived in the apartment months earlier, when the child was thought to have died. A court convicted them of murder.

Even now, however, when local police departments have their own forensic laboratories and investigators, forensic entomology remains an obscure specialty. “We are not mainstream,” says Gail Anderson, a forensic entomologist and the co-director of the Center for Forensic Research at Simon Fraser University in British Columbia. In the United States, fewer than 20 people are accredited by the American Board of Forensic Entomology.

This is unfortunate, given that arthropods can tell us a lot about how a person has died. Right after death, enzymes begin digesting expiring cells, and bacteria take over soft tissue. Soon, bugs or other arthropods arrive, including flesh flies and carrion beetles or the occasional land crab, which eat the cadaver or breed inside of it and make it their residence. These processes become extraordinarily difficult to analyze underwater. On land, bodies tend to decompose in a predictable way, but cold water can slow down or suspend decomposition, making it harder to determine the time of death. And, for obvious reasons, examining and collecting evidence in water is more difficult for investigators than on land. “You’re dealing with divers, you’re dealing with salinity,” Anderson says. Tides, currents or other forces can quickly carry evidence away or otherwise degrade or distort it. Perhaps partly because of these challenges, there are few specialists in aquatic forensics, which means a dearth of research and established best practices surrounding even basic procedures, such as preserving and collecting evidence. Which makes Magni’s well-honed sense of how to interpret evidence left by non-terrestrial organisms in punishing aquatic conditions that much more valuable. “She’s probably got her head around that stuff better than most,” says Ian Dadour, the former director of the Center for Forensic Science at the University of Western Australia and Magni’s mentor.

After submerging a panel in an Australian harbor, one of Magni’s students develops a barnacle colony that will be transferred to an aquarium for further study. Claire Martin

Specimens at the Algae Research and Development Center at the Harry Butler Institute at Murdoch University. Claire Martin

In October 2022, I met Magni at a train station in Rome, on her way to a conference on veterinary forensics. She bought a croissant and a coffee and hopped aboard a Naples-bound train, wearing ripped jeans and an orange-and-white button-down shirt. Now in her early 40s, Magni has short brown hair and big hazel eyes. Despite spending endless hours with dead bugs and decaying bodies, she is as bubbly as a glass of Prosecco, blowing kisses to friends and colleagues when taking her leave. On the train, she told me about how she collected spiders as a child. “I had a big hairy one that disappeared,” she said in English in a thick Turin accent. The thought of an arachnid crawling around the house alarmed her mother, a teacher for children with special needs, but her parents grew accustomed to Magni’s unnerving hobbies. At various times, young Paola kept insects, frogs, snakes, lizards, canaries and a hamster she won at an amusement park. She was the type of kid to ask for a microscope at Christmas. As a small child, she joined the World Wildlife Fund and brandished the badge as though she’d been accepted into an exclusive club. After learning about genetics, in middle school, she started breeding hamsters and donated the offspring to friends and the local pet shop. Later she scuba dived and considered pursuing marine biology. “I have a thing for manta rays,” she tells me.

During her undergraduate studies at the University of Turin, a professor explained to Magni’s class how insects could be used to help discern vital information in a crime scene, such as a victim’s time of death. (Traditional pathology can estimate such things, but entomology can narrow the range from a few weeks or months to mere hours.) Magni quickly knew she wanted to study this strange combination of insect science and crime science full time, but few mentors existed for the discipline in Italy, so she moved to the United States. After completing her master’s degree in forensic entomology at Michigan State University, in 2007, and taking an FBI course on discovering, recovering and identifying human remains, she returned to Turin to pursue her doctorate.

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Magni is an expert in identifying seemingly invisible clues in water and the creatures that inhabit it. Guido Gazzilli

She was nearly done with graduate school when Federica Mangiapelo was found dead. At the time, Magni, though still a student, was working on cases involving dead animals, helping law enforcement understand when and where they died. But Federica’s case became notorious throughout Italy. Virtually the whole town of Anguillara Sabazia attended her funeral. Afterward, the Mangiapelo family insisted to eager journalists that the only explanation was that Federica had been murdered.

In fact, authorities had, at first, suspected Federica’s boyfriend, a 23-year-old man named Marco Di Muro who had been with her the night she died. He told authorities that after he picked her up at home, the couple had gone to a Halloween party at a nightclub. At 2 or 3 a.m., they had a fight and left together in Di Muro’s car. He maintained that he dropped her off in front of a supermarket near the lake, several miles from her house, and afterward had gone straight home. He was adamant that he had not been to Lake Bracciano.

Surveillance video footage from a gas station told a slightly different story: Rather than spending the early morning hours at home, as he’d claimed, he was filmed filling his car with gas. Moreover, Federica’s parents maintained that Di Muro had a history of mistreating their daughter, and even that Federica had planned to break the relationship off.

Investigators searched Di Muro’s car and interviewed him five times, but they were unable to find conclusive incriminating evidence—certainly no proof that he’d been to the lake, let alone that he had killed his girlfriend.

But with local and national interest in the case remaining high, the police were pressed to determine definitively how Federica died. That was when the young Carabinieri officer recalled Magni’s presentation.

Magni at Lake Bracciano in 2022. Federica Mangiapelo’s hometown, Anguillara Sabazia, sits on the southeast corner of the lake. Guido Gazzilli

Magni had explained to the class that clothes can retain traces of plankton, sediment and soil. Moreover, she went on, if a person drowns in a pond, lake, river or ocean, they will ingest plankton along with water. When that water reaches the blood, heart and brain, it carries a type of single-cell phytoplankton called a diatom that appears in almost all natural aquatic environments. An analysis of brain or liver tissue or of bone marrow can help determine if a person was alive before they entered the water, because only a working cardiovascular system can transport diatoms from the lungs to the other organs. And if a second person was with them in the water, that person’s clothes might reveal the same type of plankton.

Magni’s first idea was to test Di Muro’s clothes for the presence of plankton to partially verify his alibi; any trace elements found on the clothes he wore that night would be extremely suspicious. Unfortunately, Di Muro’s mother had washed his clothes after the evening of the murder—but diatoms can often survive a trip through the washing machine.

Authorities, otherwise stumped and armed with a new warrant, escorted Magni to Di Muro’s home anyway. Wearing gloves, she placed his garments in individual paper bags. She also took water samples from the house’s tap, to distinguish from samples taken from the lake, and poured them into sterile containers. “I could control only a few things,” she told me.

Back at the University of Turin’s forensic chemistry lab—a basement that at the time had little ventilation, the better to prevent the stench of dead insects from invading the rest of the building—Magni began her first high-profile chemical analysis in aquatic forensics.

Assisted by another doctoral student and a lab technician, Magni used an optical microscope to identify tiny organisms, and a specific type of rotary tube mixer that mixed the clothing samples with ethanol, which the lone study on the subject had suggested was an effective method for extracting diatoms. Then, storing the water samples in a refrigerator with the light turned off, to keep algae from blooming, she asked a biologist specializing in diatoms to assist them in identification.

It was weeks before Magni got conclusive results, but the wait was worth it. Remarkably, some of Di Muro’s clothing contained clear traces of diatoms matching samples taken from the lake. And only a single diatom species matched the tap water taken from his home. “It was a goose bump moment, the meaning of what we found,” she says. “There is a match.”

Buoyed by these findings, authorities conducted a second autopsy of Federica. This time, at the direction of law enforcement, a pathologist analyzed her tissues specifically for diatoms and found them—the same type found in the lake and on Di Muro’s clothing.

Rome police arrest Marco Di Muro on December 12, 2014, for the murder of his girlfriend, Federica Mangiapelo. Massimo Percossi / ANSA

Although it took nearly two years of additional testing, legal wrangling and public pressure, in December 2014 Di Muro was charged with drowning Federica Mangiapelo. During the trial, prosecutors alleged that Di Muro had held Federica’s head underwater. Di Muro himself never spoke a word at trial. He was convicted of the murder in July 2015 and is currently serving a 14-year prison sentence.

Massimo Mangiapelo, Federica’s uncle, a journalist who subsequently wrote a book about his niece, told me that Magni’s experiments with diatoms “were fundamental” to solving the case. Di Muro had been so adamant about never having been to the lake that night that finding evidence from the lake water on his clothing completely destroyed his credibility.

For many Italians, Federica’s murder highlighted the dangers of intimate-partner violence and femicide. To this day, politicians and public figures, including Federica’s uncle and her father, who have become outspoken activists warning against the dangers of misogyny, use her story as a case study in avoidable tragedy, and in 2018, the nonprofit Federica Mangiapelo Anti-Violence Center opened just outside Rome, offering support to women in danger.

Magni still sounds slightly astonished about her success in Federica’s case. If the cop had missed her Carabinieri seminar, or if Federica had been killed at some other time of year, when the seminar might not have been so fresh in his mind, or if Di Muro’s clothes had been washed more thoroughly, she might have come up empty-handed. “The stars were aligned,” she says.

In the years since, Magni has assisted criminal investigations in countries from India to Venezuela. In one case, she and several colleagues analyzed beetle excrement to estimate the time of death of a woman who likely died from natural causes and whose best friend had mummified her and kept her upright in an armchair in their shared apartment in northern Italy—for a staggering 16 to 18 years. In another study, she assisted with the analysis of skin injuries on a 47-year-old man found in a pond in Chile. Magni reviewed photographs of four water beetles extracted from the man’s ear and chest and examined how they could explain post-mortem skin injuries. She is also testifying as an expert witness in a long-running case of an 18-year-old Italian student found murdered in 2001. Medical experts had offered conflicting and often faulty assessments of how and when the woman died. The pathologist, for example, incorrectly compared the level of moisture in the victim’s clothing with the amount of rain from the previous few days to estimate her time of death. Some of this speculation led authorities to charge and convict a man for the murder, only for him to be exonerated two years later. When the case was reopened, Magni and colleagues, by determining the life stage of dried-up larval fragments collected from the woman’s clothes, discerned that she had been killed the night she had disappeared or immediately afterward. This finding pared down the list of suspects and paved the way for future criminal charges. The case is currently in appeals.

In fact, Magni has become something of an academic celebrity in Italy, appearing regularly in interviews with the media to discuss all things forensic and even inspiring a character on “RIS Delitti Imperfetti” (“Imperfect Crimes”), an Italian show akin to the American procedural “CSI.” She also acted as a consultant and scientific adviser for the show, which spawned remakes in France, Spain and Germany. “I like the research side, but I’m good with engagement, explaining why science is important and how to improve it,” she says.

She routinely conducts training courses for law enforcement, and a handbook she co-wrote about forensic entomology is a mainstay in the labs and offices at the Carabinieri’s massive forensic science complex, in Rome, as I discovered when I visited the facility with Magni last fall. The commandant, a Carabinieri veteran named Sergio Schiavone, welcomed us warmly in his office, and after giving us a tour of the facility’s DNA, chemistry and ballistic labs, he spoke about the potential of forensic aquatics in helping the Carabinieri identify migrants who die at sea without identification while trying to flee from Africa to Europe. Unfortunately, he said, such efforts are badly underfunded.

In 2016, Magni left Italy for Australia, where she is now an associate professor of forensic science at Murdoch University in Perth. Her public profile followed. A few years ago, she was featured on billboards across Australia promoting the university. In the photograph, she smilingly strides from an imaginary crime scene trailed by student researchers, all wearing blue scrubs. “Another day in the lab,” read the ad. During a science festival in Perth that same year, she carried a magnifying glass and wore a detective-style trench coat. This stagecraft may be unusual in academia, but it has helped Magni reach people beyond the scientific community. “She’s not like the classic scientist, you know, just working alone at a desk,” says Tommaso Pacini, a chemist who worked with her on Federica Mangiapelo’s case. “She has the capability to work with people, to put people together, to create groups.”

Magni at a facility used for forensic studies at Australia’s Murdoch University, where she balances teaching, research and public outreach. Claire Martin

For Magni, outreach of this kind is especially valuable for girls and young women interested in a career in the forensic sciences. “Forensic science used to be a very male-dominated field,” says Richard Merritt, an emeritus entomologist at Michigan State University. Merritt, who served on Magni’s doctoral committee in Italy, recalls his fellow committee members’ skepticism of Magni simply because she was a rare female forensic biologist. As women have begun to climb the ranks, that attitude is slowly changing. Still, Magni says that despite “lots of women studying forensics,” there are “fewer women practicing, for the same reasons there are less women in all scientific fields”—a lack of female role models, entrenched stereotypes about scientific ability and plain old gender bias. More than half of her own undergraduate and graduate students are women, she says, and she has helped supervise dozens of theses, on such topics as “the utility of sea fauna in forensic investigation in marine environment” and the “persistence of diatoms as trace evidence in clothing fabrics.”

Her own research and collaborative spirit continue to push the boundaries of forensic entomology. In a paper published in June 2023 in the scientific journal Insects, she and her co-authors outlined protocols for best practices in bug-based crime-solving—for example, routinely obtaining temperature readings from meteorological stations near crime scenes, to accurately factor weather considerations into analyses, and inspecting soil surrounding a corpse for insects rather than strictly on the body itself. In another study, also published in Insects, in July, she and her colleagues wrapped cotton and other common fabrics around 99 stillborn piglets, to simulate human remains, and examined how blowflies, carrion beetles and other unsavory beings ate through the clothing over several weeks. The results showed that bugs can modify existing cuts and tears in fabric or even introduce new cuts and tears that investigators could easily assume are caused by bullets or knives; the paper illustrated how easily police and medical examiners might be led astray by assumptions about analyses that don’t incorporate cutting-edge research about bugs. And in September, she was a co-author of another study, published in the journal Forensic Sciences and produced in cooperation with police in India, that showed how studying ant activity and resultant bloodstain patterns can provide clues about the circumstances surrounding a person’s death, including whether the body has been moved.

Working on criminal investigations, Magni says, remains uniquely exhilarating even when it can be emotionally challenging. The cases involving murder victims stay with her. “Especially,” she adds, “women around my age.” She is the Australian ambassador for the Red Shoes project, a conceptual art initiative begun in Mexico in 2009 that aims to raise awareness about gender-based violence by displaying hundreds of pairs of red women’s shoes that symbolize women who have been killed. The effort has spread to cities across North and South America, Africa and Europe. When the installation opened in Perth, in November 2022, Magni dedicated a pair of shoes to Federica Mangiapelo.