A stray hair or a partial fingerprint could be the essential clues that seal a murder case. But a movement is afoot to incorporate maggots and flies in the routine investigation of crime. Host Steve Curwood talks with author Jessica Snyder-Sachs about her new book, Corpse: Nature, Forensics, and the Struggle to Pinpoint Time of Death.
CURWOOD: In those old TV detective shows you might see Columbo pull a notebook out of his wrinkled trench coat pocket as he hunches over a corpse. But you probably wouldn’t catch him using a butterfly net at a murder scene. Well that’s all changing, at least in the real world. One of the most difficult things to determine is the exact time of death. And increasingly investigators are finding that Mother Nature may well be the ultimate witness. Joining me now is Jessica Snyder-Sachs. She’s author of Corpse: Nature, Forensics and the Struggle to Pinpoint Time of Death. Welcome to Living on Earth.
SYNDER-SACHS: Hi, Steve.
CURWOOD: Perhaps you could introduce the subject of your book by talking about the case of the Devils Beef Tub, this case from England, and actually, at one point, you even called this case worthy of Scotland Yard lore. Please tell us the story.
SNYDER-SACHS: Right. This is a case, one of the first cases where police looked beyond their own forensic circles for help. And it starts on a late September morning in 1935, where a young woman is crossing a bridge near Moffat, Scotland. And she happens to look down. There had been a big rain a few days before so the river had been up and came down and had scattered a lot of parcels along the bank. And she looks closer and sees part of a human arm in one of them.
CURWOOD: Oh my.
SNYDER-SACHS: Right. So clearly, she runs and gets the police. They start searching this ravine, which came to be known ever after as the Devils Beef Tub, and they found 70 parcels, different pieces of human beings, which they pieced together. It looked like they had two people here, but all the identifying features had been gouged out. So it turns out a doctors wife, Isabella Ruxton, had gone missing with her familys nursemaid. But Ruxton claims his wife and the nursemaid had actually gone to Scotland on holiday, on the 16th or 17th, and that he had an alibi after that. So this all very much hinges on when the women were killed.
So – and this is the part thats worthy of Scotland lore – one of the pathologists at the University of Glasgow plucked some maggots off of one of the packages. Medical examiners, maggots are something they know, and they usually wash it off the autopsy table. But he took them down the hall, to an entomologist, a bug scientist, Alexander Mearns. And, sure enough, Mearns identified the larva, first as the larva of blue bottle fly. And he says, I can count back to when these eggs were laid. And then Mearns counts. It takes so many hours for the eggs to hatch, so many days for the larva to mature to the point where what he got was a nice, plump, third instar larva, kind of like a teenage maggot right before its ready to turn into a fly.
So he counts back and he says these were laid on the morning of September 16th, which blows Ruxtons alibi and fits with the polices scenario of him killing them and dumping their bodies that night. So the next morning, when the sun comes up, makes it nice and warm enough for flies to be about, the flies arrived, found the packages, and in fact Ruxton was convicted and executed, and after his death, it was published, his jail cell confession: he had killed his wife in a fit of rage and killed the nursemaid when she walked in and discovered them.
CURWOOD: Now, tell me, how sensitive are flies to death?
SNYDER-SACHS: The molecules that are given off at death waft into the air and up to a mile away blow flies and flesh flies can pick up those molecules and then they just follow the gradient, ever more concentrated molecules, to the scene of death. And they first start arriving – if the body is outdoors, its a sunny day – theyll start arriving within minutes.
CURWOOD: What, now, do scientists do to pinpoint the time of death?
SNYDER-SACHS: Well, this has been bedeviling pathologists for centuries. They tried all sorts of high-tech tests to test muscle excitability and eye dilation and different chemicals, and they just dont work outside the laboratory with actual murders, actual deaths. So where theyre finding success is really outside trying to medically diagnose death. But bringing in scientists, like entomologists, who are looking at the body kind of as a ecosystem, and looking at that wonderful way that nature reclaims the body, and quantifying how it does that so they can count back, to death.
CURWOOD: Now, we focused mainly on flies here, but what other parts of nature are now used in forensics?
SNYDER-SACHS: Good question. Often, its by combining different parts of nature, as you say, that they get their best time estimates, and so botanists will sometimes look for clues: a body might drop on a plant and shade it from the sun and sometimes they can estimate that way. Also, anthropologists are looking at the soil, or bedding, or whatever is beneath the corpse, and looking for products of bacterial decay. Chemists are trying to look at that and see if they can make sense out of the chaos, as in what rate do the bacteria break our muscles down into protein, amino acids and simpler chemicals.
CURWOOD: At what point in your research for this book did you first witness natures forensics in action?
SNYDER-SACHS: Well, initially, I was invited to some workshops that the entomologists give for state troopers, FBI agents, et cetera, where they used 50 pound pigs as human corpse stand-ins. And from there I was invited to assist Neil Haskell, a forensic entmologist, with his work at the so-called body farm at the University of Tennessee. And its in the back parking lot of the University of Tennessee Medical Center. You go all the way to the back of employee parking and you see a gray stockade fence, topped with barbed wire and a bio hazard sign. And after somebody opens a few padlocks you walk in, and the first thing you see, of course, are bodies – some of them just lying in the open, some of them stuffed in garbage bags, kind of protruding. There are abandoned cars, which they use sometimes, and anthropologists, entomologists, botanists are studying how the body decomposes and how they can calculate the time since death, based on their research there.
CURWOOD: This is a pretty grisly topic. What made you want to write about it in the first place and then to keep on writing?
SNYDER-SACHS: What I find beautiful is the whole ecology of how the body is taken back to nature, ashes to ashes, dust to dust. And I also like that heres one case where nature is trumping technology. You walk into a forensic laboratory and theyre filled to the ceiling with all these high tech machines, to gas chromatographs, spectrometers, you know, machines for DNA analysis. But when it comes to determining time of death, theyre useless. So you bring these ecologists in, who look at the plants and the bugs and the microbes on the body, and theyre the ones who are giving us the answers that have been sought for hundreds of years.
CURWOOD: Jessica Snyder-Sachs is author of the book Corpse: Nature, Forensics, and the Struggle to Pinpoint the Time of Death. Thanks for joining us.
SNYDER-SACHS: Thank you, Steve.
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